New Perth Bunbury Highway complete Steel or synthetic ... - Realview

■ New Perth Bunbury Highway complete
■ Steel or synthetic fibres
■ New concrete structures standard
VOLUME 35 ISSUE 3 SEPTEMBER 2009 $8.25 inc. GST

FROM THE PRESIDENT
Thankyou to Institute staff and
supportive members
This issue of Concrete in Australia
is the first to contain peerreviewed
papers. It is also the
first issue to contain a theme or
main feature - in this case, the
background to the development
of the long awaited revision of AS 3600, with three
peer-reviewed technical papers discussing the significant
engineering design implications of the new standard.
Professor Bob Warner of the University of Adelaide
discusses the background to the new standard. Professor Ian
Gilbert of UNSW examines the changes to development
length and lapped splice length for deformed bars in
tension and restrictions on using Class L reinforcement, and
Professor Stephen Foster of UNSW examines the detailing
of high strength concrete columns in the new standard.
The contributions to this special coverage on AS 3600 from
these three eminent academics, in just a short space of time,
were made possible by the enthusiasm and dedication of
our Editorial Committee Convenor Jay Sanjayan. Jay also
arranged and managed the peer review process.
The theme around AS 3600 is also timely, as the revised
edition will be one of the three main topics to be discussed
at the Technical Forum of Concrete Solutions 09 in Sydney in
September.
This issue of Concrete in Australia also has an interesting
article on the behaviour of steel and synthetic fibres in
concrete, sourced from a translation of a paper by French
researcher Pierre Rossi in the March issue of Béton Magazine
and an article on the New Perth Bunbury Highway project
in Western Australia.
For the next (December) issue of Concrete in Australia
we intend to include a feature on “Cracking in Concrete”.
Contributions in the form of technical and project-related
The revised AS 3600 will be a main
topic for discussion at the Concrete
Solutions 09 Technical Forum
papers, including new product submissions on this subject
will be welcomed. Please see opposite for details relating to
the submission of papers.
As my term as President comes to a close in September,
may I take this opportunity to thank our new CEO Graeme
Burns and the Institute’s staff, all Councillors, Branch
Committee members, and the many individuals within
the Institute and the concrete industry in general, for the
support and encouragement they have given me over the past
two years. My best wishes are extended to Fred Andrews-
Phaedonos and Liza O’Moore as they step into the roles of
President and Vice-President respectively.
Tony Kinlay
President, Concrete Institute of Australia
president@concreteinstitute.com.au
Concrete Institute of Australia
Office contact details
National and NSW Branch
Suite 2B, Level 2, 9 Blaxland Road
Rhodes, NSW 2138
PO Box 3157. Rhodes, NSW 2138
Phone: 02 9736 2955
Fax: 02 9736 2639
Email: admin@concreteinstitute.com.au
nsw@concreteinstitute.com.au
Web: www.concreteinstitute.com.au
Queensland Branch
Level 14, 348 Edward Street
Brisbane, Qld 4000
Phone: 07 3227 5204
Fax: 07 3839 6005
Email: qld@concreteinstitute.com.au
Victoria Branch
2nd Floor, 1 Hobson Street
South Yarra, VIC 3141
Phone: 03 9804 7834
Fax: 03 9827 6346
Email: vic@concreteinstitute.com.au
South Australia Branch
PO Box 559
Marden, SA 5070
Phone: 08 8300 0300
Fax: 08 8341 1591
Email: sa@concreteinstitute.com.au
Western Australia Branch
45 Ventnor Avenue
West Perth, WA 6005
Phone: 08 9389 4447
Fax: 08 9389 4451
Email: wa@concreteinstitute.com.au
Tasmania Branch
2 Davey Street
Hobart, Tas 7000
Phone: 03 6221 3715
Fax: 03 6224 2325
Email: tas@concreteinstiute.com.au
2 Concrete in Australia Vol 35 No 3

President:
Tony Kinlay
Chief Executive Officer:
Graeme Burns
Concrete Institute of Australia
PO Box 3157
Rhodes NSW 2138
Tel: +61 2 9736 2955
Fax: +61 2 9736 2639
e-mail: admin@concreteinstitute.com.au
web: www.concreteinstitute.com.au
Concrete in Australia
Technical papers on current areas of interest
are invited for peer review, as are more general
contributions on research and development,
and current or recently completed construction
projects. Letters to the Editor and newsworthy
items are also welcome.
Concrete in Australia Editorial Committee
Convenor – Jay Sanjayan
(Jay.Sanjayan@eng.monash.edu.au)
Co-convenors – Fred Andrews-Phaedonos
(Fred.Andrews-Phaedonos@roads.vic.gov.au)
Assoc Prof Rob Wheen (R.Wheen@civil.usyd.edu.au)
James Trezona (TrezonaJ@conwag.com)
Hugh Winslow (hugh.winslow@the precasters.com.au)
Prof Andrew Deeks (deeks@civil.uwa.edu.au)
ISSN 1440-656X, VOL 35 No 3
EDITOR: Bob Jackson
MANAGING EDITOR: Dietrich Georg
ADVERTISING:
NSW: Maria Mamone and Leanne Ralph
phone 02 9438 1533 fax 02 9438 5934
Vic & Tas: Wyeth Media Services Pty Ltd
10 Keysborough Close, Keysborough
Vic 3173. (PO Box 161 Dingley Vic 3172)
phone 03 9701 8844, fax 03 9701 8877
VOLUME 35 ISSUE 3 SEPTEMBER 2009
Contents
2 President’s report
4 News
14 Update on Concrete Institute Technical Projects
PROJECTS
New Perth Bunbury Highway complete 12
New motorway opens north of the Brisbane River 14
Port Botany container terminal expansion 15
PERSPECTIVE
Steel fi bres or synthetic fi bres 16
TECHNICAL PAPERS
2301
October 2008
to March 2009
The new Australian concrete structures standard 18
Development length and lapped splice length for deformed bars in tension
– changes to Section 13 of AS3600 23
Restrictions on the use of Class L reinforcement in AS3600-2009 31
Detailing of high strength concrete columns to AS3600-2009 37
ALSO IN THIS ISSUE
National Precaster 47
Pipeline 53
Post-tensioning Institute of Australia 43
Australian Concrete Repair Association 59
Concrete Masonry Association of Australia 60
Steel Reinforcement Institute of Australia 62
CCAA Library 63
New members 64
Concrete in Australia is produced
for the Concrete Institute of Australia
by Engineers Media
phone 02 9438 1533
fax 02 9438 5934
email bjackson@engineersmedia.com.au
The Murray River Bridge, south of Perth on the New Perth to Bunbury
Highway, is the largest bridge structure on the now completed 70km road.
Shown here is the bridge during incremental launching in September last
year (see project article page 12). PHOTO: SOUTHERN GATEWAY ALLIANCE
The statements made or opinions
expressed in this magazine do not
necessarily reflect the views of the
Concrete Institute of Australia nor of
Engineers Media.
VOLUME 35 ISSUE 3 SEPTEMBER 2009 $8.25 inc. GST
Concrete in Australia Vol 35 No 3 3

NEWS
Concrete in Australia review
The Institute had a pleasing response to a survey issued to
members in April 2009 in relation to member feedback
on Concrete in Australia. The survey aimed to identify and
highlight key areas of the magazine that are most valued and
areas where improvement may be implemented. The survey
responses aided in a review of the magazine that was carried
out to ensure that the Institute’s cornerstone publication
continues to provide the most relevant, requested and desired
information to issue to the membership.
Many of these changes from the review have been
incorporated in this issue of the magazine, as highlighted in
the President’s column. The responses to questions relating to
specific technical areas that members feel need to be addressed
will be correlated with the results from the recently issued
Technical Needs Survey and will assist in providing a link
in with other Institute initiatives, particularly that of the
Educational Programs.
The survey highlighted the importance of the technical papers
included in Concrete in Australia. The magazine’s Convenor,
Jay Sanjayan, has focused upon technical content which will
play a vital role in ensuring this membership need is met. The
strong desire from members to ensure that Concrete in Australia
does not become a medium for advertorials and maintains a
non-partisan position has been heeded by the Institute and
subsequent changes to the magazine’s format have been made.
The survey also assisted in the Institute obtaining
demographic information that will assist the Institute in further
activities, including a full market segmentation review to
provide direction for membership initiatives. Some key results
from the survey are indicated in the charts provided below:
Recognising Concrete in Australia is a magazine published
quarterly, how many issues have you read (in full/or in part)
during the past 12 months
Please rate the importance of the following regular
sections of Concrete in Australia.
Not at all
Respondents
Slightly
Moderately
Very
Extremely
Letters to
the Editor
News
Items
New
Products
Institute
Project
Updates
Perspective
Pieces
Project
Reports
Technical
Papers
Library
Updates
4 Concrete in Australia Vol 35 No 3

NEWS
Institute council announced
Our Secretary/Treasurer announced the
result of the elections recently conducted
for eight positions on Council at the
Institute’s annual general meeting in
Sydney on 28 May 2009.
Those elected as councillors for the
2009/2011 term appear in the list below.
They join the previously elected executive
team comprised of Fred Andrews-
Phaedonos, Tony Kinlay, Liza O’Moore
and Craig Heidrich.
The full make up of the Council for the
2009/2011 term is:
• President: Fred Andrews-Phaedonos
• Immediate Past President: Tony Kinlay
• Vice President: Liza O’Moore
• Secretary/Treasurer: Craig Heidrich.
fib – National Membership Group
The Concrete Institute of Australia has
recently established a new Australian
National Member Group with the
international federation for structural
concrete (fib). The Concrete Institute
will act as the key secretariat for the
Membership Group and has sought
confirmation from other organisations
who previously expressed a willingness
to join the Membership Group.
The Concrete Institute will
act as the key secretariat for
the Membership Group.
The Institute will harness this
opportunity which will assist in
providing greater technical information
to the membership in regards to what is
occurring on the international scene.
The Institute is appreciative of the
Environmental accreditation for
Xypex waterproofing products
Xypex Australia was recently issued
with Licence No XYP-2009 for Xypex
Admix C-1000NF and Xypex Admix
C-5000, by Good Environmental
The eight elected Councilors include
Kevin Abrams, Ian Gilbert, Doug Jenkins,
Jay Sanjayan, David Meager, Wolfgang
Merretz, Deborah Smee and Ian Bishop.
Branch representatives are:
• Queensland: Des Chalmers
• New South Wales: Julian Borgert
• Victoria: Gary Wyatt
• Western Australia: Chris Long
• Tasmania: yet to be appointed
• South Australia: yet to be appointed.
The Cement Concrete & Aggregates
Australia representative is Ken Slattery.
The new council will be installed
following the conclusion of the
biennial conference in Sydney in
September 2009.
other organisations which constitute the
National Member Group, as highlighted
below. The Institute is also appreciative of
Jim Forbes and Professor Stephen Foster
who have agreed to be the two delegates
of the National Member Group, with Jim
accepting the role of Head of Delegation.
The Institute also appreciates George
Cremasco for accepting the role of
deputy of the National Member Group.
The constituted Member Group
includes:
• Concrete Institute of Australia
• Hyder Consulting
• University of New South Wales
• Westkon Precast
• Taylor Thomas Whitting (NSW)
Pty Ltd
• Post-Tensioning Institute of Australia
• KBR
• ADG Engineers (Aust) Pty Ltd.
Choice Australia (GECA) as fully
compliant with the GECA 08-2007
Environmentally Innovative Products
Standard.
The certification endorses Xypex
Admix C-1000NF and Admix C-5000 as
environmentally preferable and therefore
suitable for consideration in applications
for buildings with Green Star Ratings
in accordance with the Green Building
Council of Australia.
Both Xypex certified products have
the ability to generate a non-soluble
crystalline formation deep within the
pores and capillary tracts of concrete – a
crystalline structure that permanently
seals the concrete against the penetration
of water and other liquids from any
direction.
Good Environmental Choice
Services Pty Ltd (GECS), assessed
the Xypex products to the criteria of
international standard ISO 14 024,
Environmental labels and declarations.
This is for products indicating overall
environmental preferability based
on multiple criteria using life-cycle
considerations.
The key environmental performance
criteria against which the Xypex products
were assessed were fitness for purpose
and environmental load reduction, where
the Xypex products were taken through
a Life Cycle Assessment (LCA). The
results calculated by Simapro 7 show that
the Xypex nominated products do have
a minimum 30% environmental load
reduction.
Additional criteria for the assessment
included material requirements,
packaging requirements, environmental
regulations and labour, antidiscrimination
and safety regulations.
Good Environmental Choice Australia,
a not-for-profit organisation, seeks to
distinguish and reward those producers
and service providers that have improved
their environmental performance and
provide an environmentally preferable
product or service, from those that do not.
The benefits of an independent
environmental label is that customers
can easily recognise products which are
sensitive to environmental pressures.
In the pursuit of a healthier
environment, Xypex Australia encourages
the industry to consider its GECA
approved products.
For further information visit
www.geca.org.au and www.xypex.com.au
6 Concrete in Australia Vol 35 No 3

concrete solutions 09
17 – 19 September 2009, Luna Park, Sydney
Your future in concrete!
Concrete Solutions 09 comes at
a critical time for all of us in the
concrete industry. Make sure
you are part of it and grab the
opportunity to position yourself to
lead the industry into the exciting
and challenging times ahead.
Join your industry colleagues in a
program of ideas, knowledge and
solutions which will assist you to
identify opportunities which will
add value and build a sustainable
future in concrete.
Hear technical presentations of
peer reviewed papers on state
of the art research, design and
application of concrete by local
and international experts.
Debate with industry experts
about critical contemporary
issues of the day – AS3600 – the
new concrete structures code,
durability and sustainability.
Don’t miss the 2009 Awards for
Excellence – recognising some
outstanding contributions to
the development of concrete
technology and practice.
Technical Sessions
A comprehensive technical program
incorporating 5 plenary sessions and 21
parallel sessions over two days has been
finalised. Papers cover both current and
developing areas of technology and practice
will be presented by leading researchers and
practitioners from Australia and overseas.
This is a critical opportunity to position
yourself for the exciting future of concrete.
Details of the program are on the web site
www.concrete09.com.au.
Technical Forum
On the first day, the Technical Forum will
provide a unique opportunity for delegates
to discuss three critical contemporary issues
– AS3600, durability and sustainability.
AS3600 – 2009, the new edition of the
Australian Standard for Concrete Structures
has been long awaited. This session will
discuss the implementation and impact of
new inclusions in AS3600 which will affect
us all.
The recent national durability workshops
organised by the Institute asked the
question – what do we want from future
durability codes This session will be the first
opportunity to discuss the initial outcomes
of those workshops and to provide further
input to this important area.
Sustainability – what does it mean for
the concrete industry This session will
provide the opportunity to discuss the
environmental, social and economic impacts
of sustainability in the concrete industry
and the effectiveness of current tools and
regulations for sustainable design.
The role of R&D
will form a background theme
to each of these topics. Case studies will be
presented demonstrating how R&D can be
harnessed at both individual and enterprise
level in the technical development process.
2009 Awards for Excellence
32 exciting entries have been received for
the 2009 Awards for Excellence, consisting of
9 Building projects, 12 Engineering projects,
2 International projects, and 9 Technology
entries.
Not only will all entries be eligible for the
Institute’s major award, the Kevin Cavanagh
Medal for Excellence in Concrete, but also
a new award has been introduced this year
for the environmentally sustainable use of
concrete across the Project and Technology
entries.
These awards will be determined by a
prestigious judging panel under the
chairmanship of Jim Forbes (Hyder
Consulting), including Ron Bracken (past
President MBA, NSW), Peter Dux (University of
Queensland), Tony Kinlay (GHD and President
CIA) and Adrian Pilton (Johnson Pilton
Walker, Architects). For the environmentally
sustainable use of concrete award, the
judging panel will be guided and advised by
Rob Rouwette (Senior Consultant, Energetics
Pty Ltd).
All entries will be presented at a Gala Cocktail
function on Friday, 18th September 2009
during Concrete Solutions 09, followed by the
presentation of Awards. We are encouraging
all entrants to invite their industry colleagues
and clients to join with us as we celebrate
excellence in concrete. Additional tickets can
be purchased through the web site –
www.concrete09.com.au.
Register NOW online at www.concrete09.com.au

NEWS
Concrete frame choice for Melbourne office building
The new ANZ Centre is under construction by Bovis Lend
Lease at Victoria Harbour on Melbourne’s Yarra River. It is
Australia’s largest office building and is regarded by Cement
Concrete & Aggregates Australia (CCAA) as an outstanding
exemplar of concrete framed construction.
CCAA said the all-concrete framed solution was selected on
this complex project because it offered construction flexibility,
economy and lower overall construction risk.
The building comprises a 10-storey section and an adjoining
five-storey section. Typically, construction of the suspended
floors takes the form of post-tensioned band beams spanning the
long direction, and reinforced concrete (RC) slabs on permanent
Inadequate foundations bring down apartments
In late June this unoccupied building still under construction
in the “Lotus Riverside” residential community in the Minxing
district of Shanghai city toppled over. Fortunately, the collapse
occurred in the early morning, but one worker was killed. The
photo suggests that the foundations were inadequately anchored
into the soft ground.
Construction work on the block appeared to have been
nearly completed, with windows fitted and a tiled facade. Other
identical blocks in the same property development remained
metal deck formwork in the other direction. The vertical load
bearing structure comprises three RC service cores and circular RC
columns.
The construction solutions adopted for both the horizontal
and vertical elements have resulted in some substantial time
efficiencies.
The ‘whys’ and ‘hows’ of using concrete on this project are
covered in the latest Concrete Concepts case study, published
by CCAA. The Concrete Concepts series is produced by CCAA
to highlight the advantages of concrete framing for multi-rise
projects in Australia. To view case studies in the series, visit
www.concreteconcepts.net.au
standing nearby.
Sub-standard workmanship has been a major concern in China’s
building sector, as the country rolls out enormous city expansions
and finishes off vast infrastructure projects. Construction-related
accidents last year included the collapse of a steel arch on a new
railway bridge, which killed several workers and a crane which fell
on a kindergarten, killing five. The collapse of dozens of schools
during last year’s Sichuan earthquake also led to a wave of public
outrage about corrupt officials and construction firms.
8 Concrete in Australia Vol 35 No 3

Waterfront venue uses recycled concrete
Doltone House at Darling Island Wharf in Sydney’s Pyrmont,
to open in October, is one of the first buildings in Australia to
use structural concrete made from recycled ingredients.
The building is also the first six-star green star rated building
in NSW and offers:
• recycled blackwater for parkland watering and toilet flushing
• trigeneration (gas fired electricity with reuse of the heated
air for absorption cooling of the building and for heating
hot water)
• heat rejection from the chillers to the harbour
• greater fresh air supply with CO 2
sensors and variable speed
fans and low toxicity materials and finishes to ensure cleaner air
• insulation throughout, with high performance glass and
building materials which minimise heat loss.
NEW PRODUCT
The new Doltone House in Pyrmont, Sydney uses structural concrete made
from recycled materials.
PHOTO: BOB JACKSON
3D ultrasonics scanning for identifying concrete defects
A new ultrasonic pulse echo testing machine, developed in
Russia and called MIRA (from the Spanish verb to look and
the English mirror) will be unveiled at the Concrete solutions
09 conference in Sydney.
The device gives an image of the inside of concrete showing
any defects or voids, as well as concrete thickness, wide cracking
and honeycombing and voids.
MIRA’s developers have produced a tester which:
• enables dry point contact for the probes
• uses shear waves instead of p-waves in a pulse echo mode,
requiring access to only one face
• has an array of transducers so that each measurement takes
nearly 100 results over an area 400mm x 200mm in a
fraction of a second
• has a built in wireless network in the measuring head so data
can be transmitted to a PC
• comes with software that combines multiple measurements,
comprising thousands of results over a large scan area, and
instantly analyses them to give a 3D image or multiple
slices through the concrete.
So far it has been used on two projects in Australia to give
PCTE, the Australian distributor, a chance to evaluate it.
On one project it was able to show that there was no loss of
concrete on the inside of a pipe section. Testing was entirely
from the outside face while the pipe was still live. On another it
showed that the defects in a beam were only in the cover zone
and not within the structural concrete.
The heart of the system is the test head, which incorporates
40 separate transducers that fire and receive during each
measurement. The multitude of readings from each
‘measurement’ gives a snap shot of the concrete below the
measuring head. The measuring head is stepped across the
concrete surface while the software pieces all of the data
together into a seamless image of the entire area. After some
initial calibrations an area 2m high x 400mm wide for example
can be scanned in a few minutes.
For more information call Reuben Barnes from PCTE on
04 0803 4668 for further information.
Concrete in Australia Vol 35 No 3 9

CONCRETE INSTITUTE PROJECTS
Update on technical projects
The Institute’s Project Manager Technical Services Ben Cosson gives an update on recent progress.
At the time of writing Standards Australia had recently made
a Public Release in response to the global financial crisis. The
release highlighted the impact this has had on their business
operations and their subsequent forward strategy and the
consequent implications that this will have on stakeholders
and organisations such as the Concrete Institute. The
implications of the financial crisis have resulted in Standards
identifying underlying resourcing and financial issues.
The Institute had previously identified two potential projects
that may have taken advantage of the Pathway options that were
available through Standards’ New Business Model, namely BD-
032: Composite construction and BD-066: Tilt-up construction.
Following the Public Release, the Institute has had discussions
with Standards Australia to identify the implications for
undertaking the identified projects. This engagement, lead to an
understanding that future projects undertaken with Standards
Australia will require significant funding investment by industry
in addition to providing committee resources. Until further
clarification is available, the likelihood of BD-032 and BD-066
proceeding appears unlikely.
AS 3600
At the time of writing the Institute had been advised from
Standards Australia that a late August 2009 publication date
was likely for AS 3600. This date will be timely for the issue
of this edition of Concrete In Australia in which AS 3600
is the feature together with the Technical Forum at Concrete
Solutions 09, whereby the implementation and impact of new
inclusions in AS 3600 will be a major topic.
the Committee providing comments and revisions for the
various draft chapters.
• Sustainability Working Group. A draft content of the
publication was in the review process prior to being
circulated to a selected number of people on the Committee
for response.
Professional development
Durability workshops
The durability workshops, which were held in June in the
major states, achieved encouraging participation rates and
valuable feedback. The feedback that was collected, together
with discussions throughout the sessions have provided the
Durability Committee with pertinent information that will be
able to be used in the future, including the revision of Z13:
Performance Criteria for Concrete in Marine Environments
and Z7: Durable Concrete Structures. The outcomes of the
workshops will be provided at the Technical Forum of
Concrete Solutions 09. In late July the Durability Committee
was in the process of analysing the State feedback that was
collected on the day.
Publications
The current status of reviewed and initiated publications as of
late July:
• CPN 29: Prestressed Concrete Anchorage Zones: Queensland
Branch has been making steady progress.
• Z 15: Cracking in Concrete Structures: The publication was at
the stage of obtaining industry feedback prior to additional
editing for peer review.
• Z 48: Precast Concrete Handbook: The release of this
publication was imminent.
• Z13: Performance Criteria for Concrete in Marine
Environments. Feedback from the recently conducted
Durability Workshops will provide valuable information
that will be necessary for the review team of Z13. The
information will be of use in both technical content and the
format in which the publication will take.
• A Current Practice Note on Geopolymer Concrete. The
draft writing of the publication was being finalised prior to
Durability Committee presenters at the QLD Workshop [l-r: Tony Thomas,
Shengjun Zhou, Godfrey Smith, David Mahaffey, Frank Papworth (Committee
Chair) and Rodney Paul].
The Institute and the Durability Committee are highly
appreciative of the response feedback obtained and the lively
interactive discussions that took place at the various state
workshops.
A follow up survey that was issued to all registrants has
provided a positive response with some sound suggestions for
future workshops that the Institute will hold. Some encouraging
responses were particularly noticed in relation to the interaction
10 Concrete in Australia Vol 35 No 3

Establishing Clients’
Durability
Requirements
Achieving Durability
in Design
Achieving Durability
in Construction
that occurred between various stakeholders of the industry
and the opportunity that the workshops provided to stimulate
greater awareness about the topic in the registrants own
organisations as indicated in the two figures above:
Technical
Members technical needs survey
In late July the Institute had drafted the Technical Needs
Survey and was in the process of finalisation prior to
distribution to the membership. The survey will aim to again
identify technical areas of high importance to members where
further information is sought.
…the portal will be an information hub
The results of the survey will be collated and together with results
of other initiatives undertaken will assist in providing a framework
for key educational programs that may be delivered throughout
the course of 2010. In addition the results will also provide further
information that can be distributed to the Branch committees that
will help in the development of Branch programs.
Development of knowledge portal
A medium term goal of the Institute is the development of
a Technical Knowledge Portal that will act as an information
hub of resources in all aspects of concrete technology, design
and construction. This will be a major development and
investment for the Institute that will be provided to add
significant membership value. The initiation of this work
has begun with sound input from the Institute’s Technical
and Knowledge Development Committees. The Committees
have engaged with Institute staff and consultants from the
information technology industry to ensure member needs are
met and that the execution of the hub delivers results that use
the most efficient forms of the available technology.
For further information on these activities, contact Ben Cosson
at the Institute’s national office on (02) 9736 2955 or by email to
technical@concreteinstitute.com.au.
Concrete in Australia Vol 35 No 3 11

PROJECTS
New Perth Bunbury Highway now complete
The New Perth Bunbury Highway (NPBH), one of the biggest infrastructure projects in Western Australia’s history,
will be officially opened this month, about three months ahead of schedule.
The project was delivered for Main Roads Western Australia
by the Southern Gateway Alliance (SGA), which was formed
in 2006 to design construct and deliver the NPBH. SGA is
comprised of Leighton Contractors, WA Limestone and GHD.
The construction included 70.5km of dual carriageway, 19
bridges, five interchanges and nine intersections as well as 32km
of shared pedestrian and cycle path, five pedestrian underpasses
and nine fauna underpasses.
The total quantities used included:
• over 55,000m 3 of concrete
• 821 piles and 146 beams for the bridges
• more than 33km of drainage structures
• about 21km of noise walls.
A central feature of the project was the fast tracked design
of the bridge structures.
Fifteen bridges were built using precast pretensioned Tee Roff
concrete beams, which were manufactured off-site by Delta
Corporation. Just two sizes of beam depth were used, with
consideration given to beam length, beam widths and bridge
skew.
Incremental launching was used for the bridges over the
two river estuaries on the route – the Murray River and the
Serpentine River. The spans were configured to enable the
piers to be placed away from the banks, to help preserve the
riparian environment and maximise navigation clearance.
At both bridge sites, minimising environmental impact and
protecting Aboriginal heritage zones were very important design
considerations.
The bridge designs were fast tracked with construction
starting before design completion. Some special considerations
relating to the bridge designs included:
• maintaining the aesthetics of the pier shape while allowing
width for launch bearings, height of pier and varying skew
between bridge locations
• avoiding the use of temporary piers by judicious design
modifications
• detailing the abutments and retaining walls to absorb
differential settlement
• using the same forms and launch girder connections for both
bridge locations
• concentrating initial prestress in lower slabs to optimise
The Paganoni Road Interchange on the New Perth Bunbury Highway.
12 Concrete in Australia Vol 35 No 3

prestress and simplify segment construction and final
supplementary stressing
• using a new prestress system with lightweight and compact
circular anchorages and a more efficient single unit coupling
system, instead of multiple components
• launching the bridges in pairs, with one crew working
between two cast beds at each site. This optimised labour
efficiency and achieved average launch cycles of one a week
• using rolling falsework instead of the traditional rolling form
to support the Condek formwork on the internal upper
forms
• using a brake saddle in front of the abutments during
launching of deck segments.
The Murray River bridge is 272m long (with maximum
spans of 46m) and uses separate structures for north and
southbound traffic. The southbound bridge carries two lanes of
traffic and a slip lane and the northbound bridge carries two
lanes and a 3m wide shared pedestrian/ cycle path. The bridge
passes over Pinjarra Road with a 9.5m clearance over the
Murray River, allowing for sufficient freeboard during a one
in 100 flood event. The bridges’ foundations are on 762mm
diameter tubular steel piles, filled with reinforced concrete.
The Serpentine River bridge also consists of two separate
structures for northbound and southbound traffic and was built
to a design similar to the larger Murray River crossing.
Each of the Serpentine bridges is 112m long and has three
spans with a maximum span length of 39.5m. They have similar
lane configurations to the Murray River bridges.
To address the aggressive environmental conditions across the
many bridge locations, the Alliance engaged GHD’s Materials
Technology Group to review all durability issues and to prepare
a durability assessment report (DAR) to classify the corrosivity
and aggressivity of expected exposure conditions, including
actual acid sulphate soils (AASSs), potential acid sulphate soils
(PASSs) and sea salt chlorides.
The preparation of the DAR culminated in the development
and design of a range of protective measures to minimise
degradation of the structural elements. Examples of such
measures include the epoxy coating of precast concrete piles
used at sites containing AASSs and PASSs and coatings and
isolation membranes for pile caps at the riverine sites containing
saline ground water.
The Pinjarra Road Interchange and Murray River Bridge on the New Perth Bunbury Highway.
Concrete in Australia Vol 35 No 3 13

PROJECTS
Northern section of Gateway Motorway opens
A new 7km section of the Gateway Motorway, north of the
Brisbane River, between the Gateway bridges and just south of
Nudgee Road, opened on 19 July.
The new motorway:
• provides a more direct route between the Gateway Bridge
and Nudgee Road
• offers enhanced access to the City, Eagle Farm and Pinkenba
areas for motorists travelling northbound via a new off-ramp
to Kingsford Smith Drive
• helps alleviate traffic congestion on the old Gateway
Motorway.
From late this year the motorway will also connect with
Brisbane Airport Corporation’s new access road and by the
middle of next year it will connect with a completed duplicate
Gateway Bridge.
Major structures on the northern part of the motorway
include new northbound and southbound off ramps where the
motorway intersects with Kingsford Smith Drive (providing
access to the CBD) and the new airport interchange.
The entire Gateway Motorway project is being delivered by
Queensland Motorways for the state government.
Design and construction is by the Leighton Abigroup
Joint Venture. SMEC and Maunsell are the principal design
consultants.
The northern 7km section of the Gateway Motorway in Brisbane opened to traffic in July. This view is to the south where the new duplicate Gateway Bridge
is currently being constructed.
PHOTO: LEIGHTON ABIGROUP JOINT VENTURE
14 Concrete in Australia Vol 35 No 3

The Port Botany expansion is now well advanced.
PHOTO: BOB JACKSON
Port Botany expansion well under way
Construction of a new 63ha container terminal at Port Botany
for Sydney Ports is now well underway. The expanded port
area is on the northern side of Botany Bay to the west of the
present terminal and about 800m east of the third runway at
Sydney Airport.
Design and construct contractors Baulderstone and Belgian
dredging specialist Jan de Nul, commenced construction just
over a year ago. Dredging, reclamation and wharf and terminal
structures, along with associated road and bridge works are
expected to be completed by the end of next year with final
terminal fitout earmarked for 2012. Parsons Brinckerhoff is the
independent verifier to the project.
The port expansion will involve:
• Creating an additional 2km of wharf face for five extra
shipping berths
• Reclaiming 60ha of land
• Dredging deep water berths to 16.5m
• Dredging 7.8 million cubic metres of fill to create shipping
channels and berth boxes
• Creating a new dedicated road access to the terminal
• Providing additional rail sidings for the terminal
• Providing additional tug berths and facilities.
Concrete in Australia Vol 35 No 3 15

PERSPECTIVE
Steel fibres or synthetic fibres
by Pierre Rossi
Civil engineering and construction professionals no longer
consider fibre reinforced concrete as exotic. This is after over
30 years of technical research and development. This positive
assessment is the result of several factors including:
• the benefit of conclusive experience (especially for steel fibre
concretes which have been used since the 1970s)
• very good technical understanding of these materials
(formulation, use, physical, chemical and mechanical
properties etc)
• the existence of national and international recommendations
on the sizing of the structures or structural elements made
up of these materials (today perfectly validated for steel fibre
concretes).
Some objective comparisons
There are now two types of fibre available on the markets:
steel fibres and synthetic fibres. When confronted by a pair of
whisky connoisseurs we want to make sure they don’t turn into
alcoholics and drink the whole bottle. Indeed, when relying on
the scientific or technical literature concerning the comparative
performances (attractions) of the two kinds of fibre, to our
dismay we find that the “thirst” often justifies the means. In
other words, we find approximations, errors and unfortunately
even bad faith (or worse) sprinkled in these learned texts. The
objective is not to play to the fibre court but to offer some of
the most objective elements possible (at least that is what we
hope) so that the users of the famous fibre can come to the
market without compromising quality. In order to get to this
point we have not chosen to make an exhaustive comparative
analysis between the two competitors, but to focus this
analysis on two important problem areas where they are clearly
differentiated. These two problems are mechanical performance
and durability.
Mechanical performance
Firstly it is useful to remember the two indispensable basic
points about fibre reinforced concrete. A fibre reinforced
concrete is a composite material made up of a matrix – the
concrete, and the reinforcement – the fibre. In a fibre reinforced
concrete the fibres spread the strain across the cracks created in
the matrix. In other words, the fibres are only useful if there are
potential cracks in the material. No cracks, no fibres.
When faced with cracks, one mechanical characteristic of the
fibre is paramount. The Young’s modulus defines the rigidity of
the fibre.
Indeed, the higher the Young’s modulus of the fibre, the better
the control of the cracks created in terms of length and opening.
These values diminish as the Young’s modulus of the fibre
increases.
This principle is essential as long as the anchoring of the fibre
in the concrete is assured. The cracks in the concrete appear
at different times in the life of the material; from the first
moments (plastic shrinkage) up to a very advanced age. As a
result these cracks appear at times in the concrete corresponding
to structural characteristics (eg: density) and mechanical
characteristics (resistance in compression, Young’s modulus)
which progressively develop.
During the first three hours the resistance of the concrete and
its Young’s modulus are very low. The compression resistance
is lower than 3MPa; traction resistance is below 0.3MPa and
Young’s modulus is below 5GPa; these figures being all orders of
magnitude.
If the concrete cracks during this period, loads to be taken
by the fibre and crack openings will be low. After 24 hours
and more the mechanical properties of the concrete increase
considerably. Compression resistance is higher than 10MPa;
traction resistance is above 1MPa and Young’s modulus is above
15GPa. These are still orders of magnitude.
During this maturation period if the concrete is forced
again to crack, the loads taken again by the fibres as well as the
openings of the crack will be much more significant.
How will the two types of fibre
behave when the concrete cracks
Steel fibres, most often have a high Young’s modulus
(200GPa) and a high resistance in traction (between 800 and
2500MPa). At a very young age, since small openings in the
cracks may appear and because of the poor anchoring of the
fibre in the not very compact matrix, these steel fibres are not
very effective against the cracks. The matrix does not pull on
the fibres perpendicularly to the cracks so the cracks also do
not react very much. The more the concrete ages, the more
the steel fibres are needed by the cracks. They respond very
effectively.
The synthetic fibres used on the concrete are mainly
polypropylene fibres. They have quite a low Young’s modulus
varying between 3GPa and 5GPa. They are offered on the
market in very small sizes (in length and diameter).
More recently another type of synthetic fibre has appeared on
the market; called polymer fibre, or macro-synthetic fibre. It is
“offered” for structural applications.
Its size is significant and macro-synthetics also have a higher
Young’s modulus than those of polypropylene fibres, varying
between 5GPa and 10GPa approximately.
Finally, two other types of synthetic fibres are also used in
concrete, but on a much lower level. These are PVA fibres
and aramid fibres with Young’s Moduli of 30GPa and 70GPa
respectively. These fibres are now used in very high and ultra
high performance fibre reinforced concretes.
The following remarks concern polypropylene fibres and
macro-synthetic fibres.
Because of their low Young’s modulus these fibres are very
reactive to potential cracks at a very young age, in particular
16 Concrete in Australia Vol 35 No 3

polypropylene microfibres. Indeed, slight displacements on
the fibres linked to small openings of the cracks in these fibres
generate sufficient loads to combat the propagation of cracks.
This effectiveness is increased because certain polypropylene
fibres are fibrillated and therefore very well anchored. This is also
the case in a not very compact and adherent matrix such as very
young concrete.
Conversely, as the concrete becomes more mature, synthetic
fibres become less significant. Indeed, because of their low Young’s
modulus synthetic fibres must undergo large displacements,
corresponding to the large openings of the cracks, to generate
appropriate seams in the cracks. Therefore, in aged and cracked
structures in concrete with macro-synthetic fibres, cracks are
much more open than with steel fibres and the deformation of
these structures may be (too) significant.
Another point to consider concerns the mechanical aspects. It
concerns the problems of creep of the fibres.
The creep of a material describes how it deforms in time
even under constant strains. Steel fibres at the levels of strain
in concrete do not creep or hardly ever. This is not the case
for synthetic fibres. In this case the creep is insignificant.
This may have negative effects. Indeed, one may encounter a
situation where in a given situation the concrete with synthetic
fibres responds correctly to the specifications of the structure
(mechanical stability, deformation, openings of cracks) and the
creep of fibres (between cracks) makes the structure “sway” in a
situation which is not acceptable with deformation (good use of
the structure) and crack openings which become too significant
(durability problems).
Durability
When people talk about the durability of fibre reinforced
concretes there are two factors involved: the material and the
structure.
The first aspect concerns the problem of corrosion of the fibres
(material). Regarding synthetic fibres, apart from some aramid
fibres, there is no durability problem in the fibre in the concrete.
Regarding steel fibres, corrosion of the fibres may obviously
occur. Experience and research conclude that:
• superficial corrosion of the fibres may cause discolorations on
the surface of the exposed structures
• surface corrosion of the fibres does not cause any fault or
disturbance in the mechanical operation of the structures
using it.
The potential corrosion of steel fibres may be minimised in
practice by:
• optimising the formulation of the fibre reinforced concrete
• using non-steel frameworks or ones with an “internal skin”
(synthetic tissue for example)
• using galvanised fibres.
The second aspect regarding the durability of fibre reinforced
concretes concerns the fire resistance of structures. Steel fibres
are not a determining factor in the fire resistance of structures.
What we can underline is that a structure in fibre reinforced
concrete behaves rather better in the presence of fire than a
normal reinforced concrete structure (fewer breaks).
Conversely, some synthetic fibres, particularly polypropylene
microfibres have a significantly positive impact on this problem.
This effectiveness is due to a very simple phenomenon: in the
case of a fire, polypropylene fibres disappear (they have reached
their fusion point) to leave in place a significant network of
fine canalisations (capillaries) shared through the volume of the
structure. These canalisations act as expansion vessels for the
water vapour generated under pressure by the fire (evaporation of
the water present in the concrete).
Regarding the durability of the fibre reinforced concrete
structures, a last important point concerns maintaining a function
required for a given structure over time. Like any covering in fibre
reinforced concrete which has to ensure a seal (eg: in presence
of water infiltrations). Because of the creep of synthetic fibres,
mentioned above, this function, currently ensured by a concrete
structure in synthetic fibres, may not be so some time afterwards.
This is a problem which does not concern steel fibre concretes.
Steel and synthetic fibres are
nowhere near as incompatible
as many people think.
Finally, in the case of prefabricated portable elements, or
structures which may come into direct contact with users,
safety problems may arise if these are steel fibre concretes. This
phenomenon mainly concerns fibre reinforced concretes with
small diameter fibres, that is under or equal to 0.25mm. Indeed,
one can never guarantee 100% that any steel fibre will not show
on the surface of the structure, which may cause injuries.
Technical solutions exist to mitigate this inconvenience,
solutions which should not be skipped. The problem of injury
caused by the fibres does not occur with synthetic fibres.
Summarising the above, it can be
said that:
• steel fibre concretes do not perform well with regard to young
age cracking, but they are very effective for the cracking in
concrete structures which have reached maturity
• polypropylene micro fibre concretes are effective in young age
cracking (plastic shrinkage)
• macro-synthetic concretes are technically less significant
than steel fibre concretes (with a problem of keeping certain
functions over time) in relatively stressed structures
• polypropylene microfibres are recommended to improve the
fire resistance of concrete structures
• care is needed regarding portable structures or in contact with
the user when they contain micro steel fibres. These micro
steel fibres can cause cuts if no technical solution is adopted.
To conclude, those who have assessed the respective
performances of the two fibres and who have left sectarianism
and bad faith at the door, may chose, in some cases to combine
the two types of reinforcing. They are no where near as
incompatible as you may think.
Pierre Rossi is from the Laboratoire Central des Ponts et
Chaussées Université Paris Est (East Paris university central
laboratory for bridges and roads) This is a translation of a paper by
Pierre Rossi, published in Béton Magazine in March 2009.
Concrete in Australia Vol 35 No 3 17

TECHNICAL
The new Australian concrete structures
standard – delays, problems and lessons
R F Warner
The University of Adelaide
After some years of delay, the fourth edition of the Australian
Concrete Structures Standard is now expected to appear by
the end of 2009 or at the beginning of 2010. Committee
BD-002 of Standards Australia is responsible for AS 3600,
and it commenced work on the fourth edition just after the
appearance of the third edition in 2001. Progress was initially
rapid and a draft for public comment was released in 2005.
The release of the draft for public comment is an important
milestone which usually occurs near the end of the preparation
process, with the new standard appearing shortly thereafter.
The ongoing delays in the appearance of the new AS 3600 led
to concern and bemusement in the construction industry, with
speculation on the reasons for the delays. Individual members of
BD-002 have frequently been asked to explain the situation and
why there has been such a delay.
The decisions that are made within BD-002, together with
the underlying debates, are of course confidential and will not
be discussed here. Nevertheless, industry questions concerning
the delays are legitimate and deserve answers. The broad reasons
for the delays also need to be addressed, not in order to find
scapegoats, but in order to learn lessons for the future. It would
indeed be unfortunate if the problems experienced by BD-
002 were to reappear when it undertakes future work. It is
thus important to identify any ongoing issues that need to be
addressed, not only by BD-002 but also by Standards Australia.
As a starting point for the present discussion it will be useful
to look briefly at the committees responsible for the concrete
structures standard, the steps needed to produce a new standard,
and the nature of the committee processes.
Committees and Processes
Committee BD-002 consists of around twenty members
who are experienced in various areas of concrete design and
construction. Most represent Australian organisations which
are actively involved in the construction industry, and in
particular in the design and construction of concrete structures.
Organisations presently represented on BD-002 include:
AUSTROADS; the Association of Consulting Engineers; the
Bureau of Steel Manufacturers Australia; Cement Concrete
and Aggregates Australia; the Concrete Institute of Australia;
Engineers Australia; the Master Builders; the National Precast
Concrete Association; the Steel Reinforcement Institute.
Standards Australia is represented by a Projects Manager who
acts as committee secretary. The Australian Buildings Code
Board also has a representative on BD-002. A further five or
so members are academics or researchers who are not chosen
primarily to represent specific institutions, but rather on the
basis of their knowledge and expertise, and their ability to
contribute to the work of Committee BD-002.
The detailed work of preparing a new standard is undertaken
in small working sub-committees of BD-002, which deal with
specialised topic areas such as strength, serviceability, durability,
etc. Sub-committee work involves reviewing and evaluating
new technical information, deciding on which information is
to be included in the standard, drafting the various clauses and
sections, and comparing draft clauses with comparable clauses
in other overseas codes and standards. The sub-committees
include co-opted outside members as well as BD-002 members,
so that the expertise of specialists can be drawn on when needed.
All decisions and draft clauses prepared in sub-committee are
reviewed and accepted or modified by the main committee.
An ongoing policy of Standards Australia is that committee
decisions have to be consensus based. It is fairly obvious that
a process based on consensus can only work if considerable
goodwill is exercised, both by individual committee members
and by the organisations represented. Nevertheless, and perhaps
surprisingly, previous concrete structures standards in Australia
have been successfully produced on the basis of committee
consensus for many years.
A final important step in the introduction of a new edition of
an Australian standard is taken by the Australian Building Code
Board. The new document has to be accepted by the ABCB
before it is referenced in the Australian Building Code (Australian
Building Codes Board, 2006). Referencing in the Building Code
means that the standard becomes a legal document applicable in
all states and territories.
The preparation of the new standard
Generally speaking, preliminary work is first undertaken to see
whether a new standard is in fact needed. In the case of BD-
002, however, work typically commences on the next edition
of AS 3600 as soon as a new edition appears. This is made
necessary by the continuing and rapid increase in knowledge
in the field of concrete structures and the continuing changes
in the industry, coupled with the time required to complete
the enormous amount of work involved in preparing such a
document. Initial planning work for the fourth edition of AS
3600 was thus initiated in 2001 and intense sub-committee
work followed shortly thereafter. The detailed work has resulted
in a number of needed changes coming into the fourth edition,
including:
• an increase in the maximum concrete strength treated in the
design rules, from 65 MPa to 100 MPa
• an extension of the design methods for columns to cover
elements made with high strength concrete
• a change in the treatment of loads, actions, action effects
and other design concepts, with different nomenclature and
18 Concrete in Australia Vol 35 No 3

terminology, to align with the new suite of Standards, AS/
NZS 1170, Parts 0 to 4, in which the general requirements
and design methods for all materials are spelled out
• the introduction of completely new strength design check
procedures to allow the use of sophisticated analytic methods,
such as linear and non-linear finite elements, in the strength
design of members and structures
• an extensive redraft of the strut-and-tie provisions within its
own section
• a revised treatment of the design of walls
• new, updated treatments of fire resistance and durability
• updated information on the structural properties of steel and
concrete.
These and other important changes were introduced into a first
draft document which was reviewed, edited and modified by the
main committee. The draft was then edited by Standards Australia
and issued for public comment in 2005 as Document DR–05252
(Standards Australia Committee BD-002, 2005). The contents of
the document are discussed in some detail in Warner et al, 2007.
The final phase in the preparation of a new edition of AS 3600
begins with a careful consideration of the public comments. These
are acted on, as appropriate, and a “near-final” voting draft is
prepared and edited. All members of BD-002 vote on whether or
not to accept this document as the new standard. The expectation
is that members, having been closely involved at all stages in both
the preparation of the draft and the underlying consensus-based
decisions, will vote in the positive. A member who casts a negative
vote is required to explain the reasons for the negative vote and
give specific details of the clauses considered to be inadequate, with
suggested alternatives. Traditionally, minor drafting problems have
not been considered as a substantial reason for a negative vote.
Since all important decisions are made by consensus, any negative
vote has to be discussed in detail by BD-002. Much effort can
go into finding a compromise position which is acceptable to the
whole committee. When consensus has been obtained and the
necessary modifications made to the document, it is ready for
publication, possibly following minor editorial work by SA staff.
Delays and problems
It will be clear, purely from the date of issue of the document
for public review, that the delays and problems arose during
the final phase of preparing the new edition. Furthermore, a
detailed comparison of the final standard with the 2005 draft
document for comment, DR 05252, shows that only relatively
minor changes were made, despite the years of delay.
Some changes were in fact made to new clauses which deal
with the design of columns with high strength concrete, and in
particular to the clauses for confinement of the concrete core.
These requirements have been relaxed somewhat in the final
version of AS 3600. Other changes were also made, for example
to clauses dealing with durability. From a broad viewpoint,
however, the changes were relatively minor and were rapidly
completed once it was decided that they should be made.
Concrete in Australia Vol 35 No 3 19

TECHNICAL
Adverse public comment was not therefore the cause of the
delay; nor were any major inadequacies in the original draft for
comment. The delays in fact arose because of committee processes
and in particular because of the requirement for consensus
decision making.
When consensus is a prerequisite for decision making, it
is understandable that some policy decisions might become
lengthy. Rather unexpectedly, experience in BD-002 has shown
that technical decisions, and the underlying debates, can also
be prolonged. Indeed, technical debates can extend indefinitely
if members repeatedly demand additional time to search the
literature and to undertake new research in order to produce
additional technical evidence to support a particular viewpoint.
With interminable delays occurring in the final phase of the
process, it was only recognised belatedly by Standards Australia
that (a) consensus would not be achieved, and (b) that a method
of resolution would therefore have to be devised, notwithstanding
its consensus policy. The delays were overly long. Unfortunately,
information on progress (or lack of progress) was never made
available to the affected industry. Furthermore, members of BD-
002 were not informed of the development of a resolution process
and in time became frustrated and annoyed with the stalemate
following years of hard work.
A two-stage process of resolution was eventually implemented
by Standards Australia. The first step was a further attempt
to obtain consensus using external mediation experts. Given
the long history of bitter dispute it was clear to most BD-002
members taking part that this attempt was going to be a waste
of time and money, which it was. In the second step, cases for
and against the outstanding negative votes were presented to,
and adjudged by, several independent outside technical experts.
The issues were thus resolved with little change to draft, but
without consensus.
There is a further aspect to this story. Standards Australia and
the Australian Building Code Board are the two organisations
intimately involved with, and responsible for, the production
of Codes and Standards in this country. Both underwent
significant changes during the time that AS 3600 was being
prepared. In the early 2000s ABCB introduced the requirement
that a Preliminary Impact Assessment, possibly followed by a
full Regulation Impact Statement, is needed before any new
standard can be accepted for referencing in the Building Code.
This significant change reflected new government policies
concerning regulation, free trade and competition. In brief, the
purpose of the assessment is to show that the new document
will result in “net benefits” to industry.
BD-002 had already commenced work on the new standard
when this requirement was introduced, and no preliminary
assessment was undertaken. In view of the delays already
experienced, BD-002 and Standards Australia decided earlier this
year (2009) to proceed forthwith with publication of the new
edition, AS 3600–2009. As a result, BD-002 is now preparing
an impact assessment, together with a Commentary, while
publication of the standard proceeds. This means that the new
standard will probably not be called up initially by the Building
Code, although this can be expected to occur in time. The legal
situation in the interim thus needs to be considered by designers
when they choose which standards to work from.
It is important to note that Standards Australia has also
undergone very significant changes over the past decade. New
documents and guidelines for chairpersons and members of
committees have recently been prepared, which give information
on SA committee processes and on the meaning of consensus
(Standards Australia, 2008a; 2008b; 2008c). A new SA Business
Plan (Standards Australia, 2008d) addresses, among other things,
the problem of financing work on new standards and revisions.
While these recent developments do not affect the fourth edition
of AS 3600, they will be relevant to the future work of BD-002.
In particular, the problem of funding future editions of AS 3600
will raise interesting issues concerning independence. These will
be discussed shortly.
Lessons
What lessons can be learnt from the delays that occurred in the
preparation of AS 3600 It is clear that a number of changes
need to be made to committee processes in BD-002 and,
possibly, in other Standards Committees. While it might be
argued that these are all internal matters for Standards Australia,
it should be remembered that the concrete structures standard
is vital to the construction industry throughout Australia. The
industry supplies BD-002 with its members and also in no
small measure supports the work of BD-002 financially. It is,
in a real sense, the owner of the standard. Problems relating to
the production of the concrete standard are therefore problems
of the industry. While the following comments and suggestions
are personal, they are offered in the interests of the writers and
owners of the concrete standard. They are aimed at improving
procedures within BD-002 in order to avoid problems in the
future. However, they relate very much to Standards Australia
policy and processes. Indeed, three of the main lessons to be
learnt concern fundamental pillars of Standards Australia policy:
consensus, transparency and the independence of committees.
The main issues will be discussed in turn.
Going beyond consensus
Although consensus is a key platform of SA policy, the concept
now needs to be re-evaluated. Despite recent experience in
BD-002, consensus need not necessarily be a quaint relic of the
20 th Century. As previously mentioned, consensus had worked
reasonably well for BD-002 for many years, mainly because of
the goodwill of committee members. It will also have its place
in the work of future BD-002 committees.
Consensus decision making does not work well in a democratic
environment in the case of political and commercial processes.
It can work (but not always) in technical and scientific decision
making. The decisions that are involved in preparing a standard
for the construction industry are complex and not purely
technical; they often include commercial and political aspects.
It therefore has to be recognised that consensus will not always
work in BD-002 and effective resolution procedures must be
defined unambiguously, so that they can be employed without
delay when committee consensus is not achieved. Interestingly,
the likelihood of achieving consensus might be improved
substantially if such procedures are spelled out in advance and
it is known that they will be used when necessary. With such
20 Concrete in Australia Vol 35 No 3

procedures in place, consensus can remain a realisable aim in
most of the committee decision-making processes.
Before discussing specific resolution procedures, we need to
consider the current SA definition of consensus. According to SA
Guideline 1 on Preparing Standards (Standards Australia, 2008a),
consensus does not require the agreement of all members of a
committee. In fact consensus is “deemed” to be achieved if 80 per
cent of the votes are affirmative and 67 per cent of members have
voted affirmatively. However, a crucial rider to this very reasonable
definition is that no “major interest” maintain a negative vote.
This rider is a serious point of weakness. It can lead to
committee paralysis if there is just one ill-used vote, supported
by the argument that it represents a major interest. This rider
on consensus seems to be unique to Standards Australia. For
example, it does not appear to be a requirement in international
standards organisations such as ISO. It would seem to be a simple
matter to remove the rider and thereby circumvent much of the
difficulty experienced in BD-002.
Otherwise, resolution has to come from outside of the
committee. A decisive process of resolution, and not compromise,
has to be established and should be employed promptly if a small
minority of committee members do not accept the views of the
substantial majority, following extensive discussion. Resolution
by a judgement on the technical issues in dispute by one or
more independent experts has recently been seen to work. The
experts must of course have knowledge and expertise in the
area of dispute. If a committee decision is non-consensus based,
following a sustained negative vote by a sector of the industry, the
option always exists for that sector to withdraw its name from the
list of organisations responsible for producing the standard.
Transparency
During the lengthy final phase of preparing AS 3600 the
general community was unfortunately left in the dark, as indeed
were members of BD-002 during the end game, in relation to
the ongoing delays. This led to general frustration and concern.
The delays were perhaps understandable, but it was a mistake
to allow confidentiality to take precedence over transparency.
The lesson to be learnt is that transparency is always important,
not only “in the large” but also in the detail. The need is
simple: in future, BD-002 and, where appropriate, SA need to
give regular updates on current work in progress, or on lack
of progress and the reasons for lack of progress. Trade journals
and research journals provide a ready vehicle for distributing
this information. Transparency, with regular updates on progress
and problems, could also lead to fresh input from outside the
committee which in turn could help in achieving consensus.
Independence
In its new Business Plan (Standards Australia, 2008d),
Standards Australia makes clear that funding for new work
on writing and updating standards has to come from the
relevant industry or industries that will use the standard. This
is understandable, especially given the present serious financial
situation of Standards Australia. Nevertheless, it will be
extremely important to ensure that independence is maintained,
especially in situations where one sector or “major interest”
provides most of the funding and controversial decisions have
to be made. Extrapolating from experience in BD-002, it seems
that transparency in the small, as well as in the large, will be
of the utmost importance in the future in order to avoid any
possible nexus between the making of detailed technical and
policy decisions and the sources of funding.
Another way of preparing standards:
An alternative to the committee approach
In reviewing the work of BD-002 over the past years, a
question arises as to whether the committee process is in fact
the best place for preparing a new standard. While an overall
review by a fully representative committee will always be
necessary, alternative and more efficient working modes should
be sought for undertaking the detailed drafting work. One
interesting possibility is to commission a small team of two or
three independent experts to work full time with the aim of
producing a draft within, say, a six or nine month period, for
submission to the overseeing committee. Such a team should be
quite small, perhaps consisting of just one respected academic
and one experienced design engineer. For this approach to work
effectively the individuals would have to be relieved of all other
professional commitments during the project. Their work would
therefore have to be fully compensated. There are considerable
potential advantages to this approach when compared with
the traditional committee process. Firstly, it recognises the fact
that most of the committee work is in any case done by a very
small minority of BD-002 members. Secondly, it should be
considerably less costly, globally, and should short circuit special
interests. Thirdly it should be a much quicker process. This
approach has in fact been used overseas.
Other lessons
There are other lessons, less important but nevertheless valuable,
to be learnt from recent experience in BD-002. Several are
mentioned very briefly here.
It has frequently been suggested that Australia should simply
adopt overseas standards, such as Eurocode or ACI and avoid
the expense of writing its own standards. There are too many
unique local features, ranging from material properties to legal
requirements, that make this suggestion unworkable in the case
of AS 3600. On the other hand an enormous amount of work
goes into producing overseas codes and standards and BD-002
needs to make maximum use of the resulting, freely available
information. Overseas standards should be used, both for source
material (which will have to be adapted to local use) and for
comparison purposes. By comparing our clauses and rules with
those in overseas standards and codes we can make useful (but
not necessarily infallible) checks on the safety and adequacy of
our own design rules. Use has of course been made in the past of
overseas codes and standards, but even more needs to be made in
the future.
The local trialling of key new design concepts in industry
is always a desirable and useful exercise, but is only successful
if (a) it is undertaken at an early stage in the development of
a standard, and (b) there are design offices with the needed
expertise that are willing and able, financially, to participate.
Concrete in Australia Vol 35 No 3 21

TECHNICAL
A simple but important lesson in committee work concerns
the delays that occur when new technical information is
continuously sought. A time line has to be drawn for technical
discussions so that only the results of existing published research,
existing test data and other currently available information can
be used. New technical information of course becomes available
regularly, but its place is in the next revision of the standard. If
crucial developments do occur, or errors are found in the existing
standard, “green slip” amendments can always be printed quickly.
A considerable saving of time and energy might also be
achieved if new members of BD-002 were inducted into
committee processes and procedures. Induction procedures can
be overdone, tiresome and a waste of time. However, they can
also be used to avoid counter-productive activities in committee.
In this respect, documents recently prepared by SA (Standards
Australia, 2008a; 2008b; 2008c) could well be put to good use.
Concluding Remarks
With the publication of the fourth edition of AS 3600 now
imminent, the need is to move on and put the important new
information contained in it to good use. However, problems
and issues arose during its preparation and there are lessons to
be learnt and acted on. Attention has been focussed here on
these problems and issues and suggestions have been made for
improving committee processes in order to avoid problems in
the future.
Three of the suggestions concern key Standards issues:
consensus, transparency and independence. It is clear that simple,
unambiguous and effective procedures need to be available when
committee consensus is not going to be achieved. Ironically,
when these procedures are put in place they could well reduce
the likelihood of consensus not being achieved. Transparency
is required in committee work, not just in the large but also in
the detail of committee work. This can easily be achieved by
providing regular updates via the technical journals on progress
and problems in BD-002. This would benefit the many users of
the concrete standard. A major concern for the future, not only in
relation to the work of BD-002 but fairly generally in Standards
Australia, concerns the need to maintain independence in all
technical decision making and standards preparation work, while
obtaining adequate financial support to undertake the work.
A suggestion has been made in this paper to bypass much of
the detailed work undertaken by BD-002. Drafting work, which
is always difficult and time consuming, might well be undertaken
more efficiently, more rapidly and less expensively by contracting
it out to a small group of independent experts who are fully
reimbursed for their work. On a final note, it should be clear to
readers that this paper does not seek to present the views of either
BD-002 or Standards Australia. The views are purely those of an
individual long-term member of Committee BD-002; however, it
is hoped that they will be received favourably, perhaps even with
consensus, in BD-002 and beyond.
References
Australian Building Codes Board (2006), Building Code of
Australia (BCA), ABCB.
Standards Australia (2008a), Standardization Guide No. 1:
Preparing Standards.
Standards Australia (2008b), Standardization Guide No. 3:
Committee Members – Their Roles and Responsibilities.
Standards Australia (2008c), Standardization Guide No. 5:
Technical Governance of the Standards Development.
Standards Australia (2008d), Introducing a new business model for
Standards Australia.
Standards Australia Committee BD-002 (2005), Concrete
Structures, Document DR–05252, Draft for Public Comment,
Standards Australia.
Standards Australia Committee BD-002 (2009), Australian
Concrete Structures Standard, 4 th Edition, AS 3600–2009,
Standards Australia.
Warner, R.F., Foster, S.J. and Kilpatrick, A.E. (2007), Reinforced
Concrete Basics, Pearson Prentice Hall, Melbourne.
Guide to Tilt-up Design and Construction
A joint publication produced with Cement Concrete and
Aggregates Australia. Available via the Institute’s web
site or through Standards Australia/SAI Global.
The Guide uses an 'issues-based' approach and
therefore comments on matters peculiar to the design of
tilt-up construction.
In suggesting an overall design approach and then
discussing specific issues, the Guide alerts designers to
those issues that may be significant for their particular
project. The Guide is generally aimed at single-storey
structures, though some of the principles and details apply to
the use of the method in multi-storey buildings. Targeted to
engineering designers the Guide does include some
information on finishes and the range of building types for
which tilt-up is suitable.
22 Concrete in Australia Vol 35 No 3

TECHNICAL PAPER (PEER REVIEWED)
Development length and lapped splice length
for deformed bars in tension – changes
to Section 13 of AS3600 *
Professor Ian Gilbert
Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering
The University of New South Wales
SUMMARY: The existing provisions for development length and lap splice lengths for deformed bars in tension in
AS3600-2001 (Clauses 13.1.2 and 13.2.2) are out of step with the other major international codes/standards, including
ACI-318 and Eurocode 2, and they model the test data poorly. For bars in beams and columns at close centres, AS3600-
2001 may be unduly conservative. For small diameter bars in slabs at clear centres greater than 150 mm, it specifies
unsafe lap lengths – often over 50% shorter than specified in any other international code. This has been confirmed in
independent tests undertaken in 2008 both at the University of Queensland (Yates, 2008; O’Moore & Dux, 2009) and
at the University of New South Wales (Yeow, 2008; Gilbert, 2008). As a consequence, the provisions of Clauses 13.1.2
and 13.2.2 have been revised and the new rules are presented and discussed in this paper. The proposed revision is easy
to use and brings the Standard into line with the test data and the other major international codes. It also provides
Australian designers, for the first time, with the fl exibility to take into account the beneficial effects of confinement by
transverse reinforcement and transverse pressure.
1 INTRODUCTION AND BACKGROUND
In the middle 1990s, a working group, which included
representatives of the steel reinforcement industry, the concrete
industry and academia, was established by Standards Australia
to review the anchorage and splicing provisions of AS3600-1994
(Section 13). The provisions had been developed in the early 1980s
for the first edition of AS3600. The working group concluded
that AS3600-1994 was out of step with the other international
standards and also performed poorly when compared to the
available test data, ie. it was a poor predictor of anchorage failure
(Gilbert, 1997; 2007).
A revision (Gilbert, 1997) was proposed for estimating the
development length and lapped splice length for deformed bars
in tension that was based on the approach in Eurocode 2 and was
accepted and endorsed by the code committee BD-002 in 1999.
At this time, a full revision of AS3600-1994 was underway and
the changes to Section 13, along with the provisions for high
strength concrete, the inclusion of strut and tie modeling and
many other important inclusions were being developed. Also
being prepared was Amendment 2 to AS3600-1994 which was
intended to be an interim measure to facilitate the introduction of
500 Grade reinforcement and to clarify the wording and intent of
other clauses. At the 11 th hour, what was to be Amendment 2 of
AS3600-1994 became the third edition of the Standard, AS3600-
2001. This edition of the Standard was not issued for public review
* This paper was accepted for publication following peer
review on 7/7/09. © Concrete Institute of Australia, 2009.
and did not include many of the changes that had been accepted
by BD-002 prior to 2001 for inclusion in the next revision of the
Standard. This background to the third edition of the Standard is
alluded to in the preface of AS3600-2001.
Subsequent to the publication of AS3600-2001, the code
committee continued work on the current major revision of
AS3600 and Section 13 was reconsidered. A thorough review of
all available research from Australia and elsewhere confirmed that
the current design requirements in Section 13 of AS3600-2001
for calculating lap lengths for bars in slabs underestimated the
required lap lengths, particularly when the bar spacing exceeds
150 mm. Comparisons with other major international standards
such as ACI 318-05 and Eurocode 2 further confirmed that the
lap lengths calculated in accordance with AS 3600-2001 for widely
spaced N12 and N16 bars in slabs are amongst the lowest in the
world and had inadequate factors of safety (Gilbert, 2007). On
the other hand, these comparisons also showed that the lap lengths
calculated in accordance with AS 3600-2001 for larger diameter
bars at close centres in beams and columns, overestimated the
required lap lengths and may be safely reduced. It was also noted
that the provisions of Clauses 13.1.2 and 13.2.2 in AS3600-2001
did not account for the industry wide upgrade from 400 Grade
to 500 Grade steel. In summary, it was found that development
length and lapped splice lengths specified in AS3600-2001 are
poorly calibrated and a major revision was indeed necessary.
As a consequence, the provisions of clauses 13.1.2 and 13.2.2
have finally been revised and the new rules are presented and
discussed in this paper. The proposed revision is easy to use and
Concrete in Australia Vol 35 No 3 23

TECHNICAL PAPER
(a) Forces exerted on concrete by a deformed bar in tension.
(b) Tensile stresses in concrete.
(c) Horizontal splitting due to insufficient bar spacing. (d) Vertical splitting due to insufficient cover. (e) Splitting (bond) failure at a lapped splice.
Figure 1. Splitting failures around developing bars.
(a) Contact splice in plane of slab (100% of A s
spliced at a single location).
(b) Non-contact staggered splice (50% of A s
spliced at a single location).
Figure 2. Contact and non-contact lapped splices.
brings the standard into line with the test data and the other major
international codes. It also provides Australian designers, for the
first time, with the flexibility to take into account the beneficial
effects of confinement by transverse reinforcement and transverse
pressure. That these important revisions have taken more than a
decade to appear in AS3600 is a pity.
2 DEVELOPMENT LENGTH AND LAPPED SPLICE
LENGTH FOR DEFORMED BARS IN TENSION
When designing a reinforced concrete member for the strength
limit states, it is assumed that the stress in the tensile reinforcement
at the critical section can not only reach the yield stress, f sy
, but
can be sustained at this level as deformation increases. If the
yield stress is to be reached at a particular cross-section, the
reinforcing bar must be anchored on either side of the critical
section. Stress development can be obtained by embedment of
the steel in concrete so that stress is transferred past the section
by bond, or by some form of mechanical anchorage.
Codes of practice specify a minimum length, called the
development length, L sy.t
, over which a straight bar in tension
must be embedded in the concrete in order to develop the yield
stress. The provision of anchorage lengths in excess of the specified
development length for every bar at a critical section or peak stress
location ensures that anchorage or bond failures do not occur
before the design strength at the critical section is achieved.
At an anchorage of a deformed bar, the deformations bear on the
surrounding concrete and the bearing forces F are inclined at an
angle β to the bar axis as shown in Figure 1a (Goto, 1971). The
perpendicular components of the bearing forces exert a radial force
on the surrounding concrete. Tepfers (1979; 1982) described the
concrete in the vicinity around the bar as acting like a thick walled
pipe as shown in Figure 1b and the radial forces exerted by the
bar cause tensile stresses that may lead to splitting cracks radiating
from the bar if the tensile strength of the concrete is exceeded.
Bond failure is often initiated by these splitting cracks within the
development length L sy.t
of an anchored bar (Figures 1c and 1d)
or within the lap-length L s
at a lapped tension splice (Figure 1e).
Transverse reinforcement across the splitting planes (A tr
in Figures
1c and 1e) delays the propagation of splitting cracks and improves
bond strength. Compressive pressure transverse to the plane of
splitting delays the onset of cracking in the anchorage region
thereby improving bond strength.
For a reinforcing bar of diameter d b
, the design bond strength (ie. the
ultimate bond force over the development length) is φ π d b
L sy.t
f b
and
24 Concrete in Australia Vol 35 No 3

this force must not be less than the design ultimate force in the
bar A st
f sy
= f sy
π d b2
/4. That is
and therefore
L
d f
b sy
. 4 f f
sy t
b
φ π d b
L sy.t
f b
≥ f sy
π d b2
/4
Reinforcing bars in tension may be spliced together by welding
or by a mechanical anchorage or by overlapping the bars by a
specified length, L s
, as shown in Figure 2. In this latter anchorage,
known as a lapped splice, each bar must be able to develop the
yield stress within the lap length L s
, and the design force in the
bar on either side of the splice (A s
f sy
) must be safely carried across
the splice without bond failure. Both contact splices (s b
= 0)
(1)
and non-contact lapped splices (s b
> 0) are frequently used. The
mechanism of bond transfer at a lapped splice is quite different
from that at a developing bar with no adjacent bar developing stress
in close proximity, so in general where the bars at a lapped splice
are required to develop the yield stress, the specified lap length is
greater than the development length.
3 THE PROPOSED NEW CLAUSES
3.1 Development Length for Deformed Bars
in Tension
Wording
The revised wording for the Clause 13.1.2 Development length
for a deformed bar in tension is as follows:
13.1.2 Development length for a deformed bar in tension
13.12.1 Development length to develop yield strength
The development length (L sy.t
) to develop the characteristic yield strength (f sy
) of a deformed bar in tension shall be
calculated from either Clause 13.1.2.2 or 13.1.2.3.
13.1.2.2 Basic development length
The development length in tension (L sy.t
) shall be taken as the basic development length of a deformed bar in tension,
(L sy.tb
), calculated from the following equation:
L
sy.tb
05 . kk f d
3
=
k f¢
1 sy b
2 c
29kd
1 b
… 13.1.2.2
where k 1
= 1.3 for a horizontal bar with more than 300 mm of concrete cast below the bar; or
= 1.0 for all other bars
k 2
= (132 – d b
)/100, and
k 3
= 1.0 – 0.15(c d
– d b
)/d b
(but 0.7 ≤ k 3
≤ 1.0)
where c d
is the smaller of the concrete cover to the deformed bar or half the clear distance to the next parallel bar
(see Figure 13.1.2.3(A) for values of c d
)
The value of f c
¢ shall not be taken to exceed 65 MPa; and the bar diameter (d b
) is in millimetres.
The value of L sy.tb
shall be (a) multiplied by 1.5 for epoxy-coated bars; (b) multiplied by 1.3 when lightweight concrete is used;
and (c) multiplied by 1.3 for all structural elements built with slip forms.
13.1.2.3 Refined development length
Where a refined development length is required, the development length in tension (L sy.t
) shall be determined from the following
equation:
L sy.t
= k 4
k 5
L sy.tb
…13.1.2.3
where k 4
= 1.0 − Kλ (but 0.7 ≤ k 4
≤ 1.0)
where λ = (ΣA tr
− ΣA tr.min
)/A s
Concrete in Australia Vol 35 No 3 25

TECHNICAL PAPER
ΣA tr
= cross-sectional area of the transverse reinforcement along the development length L sy.t
ΣA tr.min
= cross-sectional area of the minimum transverse reinforcement, which may be taken as 0.25A s
for beams and 0 for slabs
A s
= cross-sectional area of a single anchored bar of diameter d b
K = is given in Figure 13.1.2(B)
k 5
= 1.0 − 0.04ρ p
(but 0.7 ≤ k 5
≤ 1.0)
ρ p
= transverse compressive pressure, in megapascals, at the ultimate limit state along the development length
perpendicular to the plane of splitting
The product k 3
k 4
k 5
shall be not taken as less than 0.7.
(a) Straight bars c d
= min (a/2, c 1
, c). (b) Bent or hooked bars c d
= min (a/2, c 1
). (c) Looped bars c d
= c.
(d) Lapped splice c d
= min (a/2, c).
FIGURE 13.1.2 (A) VALUES OF c d
FOR BEAMS AND SLABS
K=0.1 K=0.05 K=0
FIGURE 13.1.2 (B) VALUES OF K FOR BEAMS AND SLABS
Basic Development Length
The expression for the basic development length of a deformed
bar in tension in Eq. 13.1.2.2 is similar in form to Eq. 1, with
the average design ultimate bond stress φ f b
given by
f f
b
k f¢
2 c
=
2 kk
1 3
The average design ultimate bond stress φ f b
is directly related to the
tensile strength of concrete and modified by coefficients of varying
form and complexity to account for the various factors that affect
(2)
the bond strength, including bar location in the cross-section, bar
diameter, bar spacing, concrete cover to the bar being developed
and the confining effects of transverse reinforcement and transverse
pressure. As the average ultimate bond stress is a property of the
concrete and a brittle bond failure should be avoided, the appropriate
magnitude of the strength reduction factor φ that has been included
in the calibration of Eq. 1 in the Australian Standard is 0.6. This value
of φ is considered to be sufficient to accommodate the additional
tensile force that may develop in the bar due to strain hardening
and also allow for considerable plastic deformation in the steel bar
at the anchorage without bond failure and bar pull-out.
26 Concrete in Australia Vol 35 No 3

Figure 3. Concrete confinement dimension c d
.
A two tiered approach is proposed for the development length of
a deformed bar in tension. In any situation, a designer may adopt
the simpler lower tier approach of Clause 13.1.2.2 and specify the
development length (L sy.t
) as the basic development length (L sy.tb
)
given in Eq. 13.1.2.2. Alternatively, in situations where the beneficial
effects of transverse reinforcement and/or transverse confining
pressure exist along the development length, the designer may opt
for the refined upper tier approach of Clause 13.1.2.3.
The expression for the basic development length given in Eq.
13.1.2.2 is significantly different to the expression in AS3600-2001
and has been calibrated to provide an appropriate factor of safety
against bond failure at a developing bar. A wide range of test data
was used in the calibration. When specifying the development
length using Eq. 13.1.2.2 there is no need to consider or include a
strength reduction factor (φ) as an appropriate strength reduction
factor has been incorporated into the expression. Unlike the previous
expression in AS3600-2001, the new expression for the basic
development length provides development lengths that have an
adequate and consistent factor of safety against brittle bond failure
and that are compatible with the development lengths specified
in the other major international Standards including ACI 318-08
(American Concrete Institute, 2008) and Eurocode 2 (European
Committee for Standardisation [CEN], 2004).
The factor k 1
in Eq. 13.1.2.2 (and Eq. 2 above) accounts for the
position of the bar in the structure and increases the development
length for bars with more than 300 mm of concrete cast below the
bar (such as the top bars in a beam or thick slab). Such bars may
be subjected to a reduction in bond strength due to settlement of
fresh concrete below the bar and an accumulation of bleed water.
Both effects occur along the underside of the bar. The factor applies
only to horizontal bars in slabs, walls, beams and footings; it does
not apply to sloping or vertical bars, to fabric, or to fitments. There
is a step increase in the value of k 1
when the depth of concrete cast
below the bar reaches 300 mm (ie. the value jumps from 1.0 to
1.3). There is evidence that bond loss can occur with even shallower
concrete depths and it may be prudent to linearly vary k 1
from 1.0,
when the depth of concrete cast below the bar is less than or equal
200 mm, to 1.3 when the depth is 300 mm (or more).
The factor k 2
accounts for the reduction in the average ultimate bond
stress as the diameter of the reinforcing bar increases and varies linearly
from k 2
= 1.2 when d b
= 12 mm to k 2
= 0.92 when d b
= 40 mm.
The factor k 3
accounts for the confining effect of the concrete
surrounding the bar and depends on the concrete cover to the
anchored bar (c 1
or c in FIGURE 13.1.2(A)) or the clear distance
to the next parallel bar (a in FIGURE 13.1.2(A)). The dimension
c d
is used in the expression for k 3
, where c d
is the thickness of the
appropriate concrete ring surrounding the development length
shown in Figure 3 (c d
is the smaller of the side cover, c 1
, the cover
to the soffit (or top) surface, c, or half the clear distance to the next
parallel bar, a/2). When c d
is less than or equal to the bar diameter,
k 3
= 1.0. When c d
is greater than or equal to twice the bar diameter,
k 3
= 0.7. When c d
is between d b
and 2d b
, k 3
varies linearly between
1.0 and 0.7.
The average ultimate bond stress is directly related to the tensile
strength of concrete, which is taken in the Standard to be
proportional to f c
¢ and, hence, the term f c
¢ is included in Eq.
13.1.2.2. Due to the very limited experimental data available for
development lengths of deformed bars in high strength concrete, an
upper limit of 65 MPa has been placed on the concrete strength. The
minimum value of L sy.tb
(29 k 1
d b
) is applicable to a steel yield stress
of 500 MPa and is based on the formula 0.058d b
f sy
from AS1480,
(1982) and Ferguson (1988).
Due to the reduced average ultimate bond stress, the development
length for an epoxy-coated bar is significantly longer than for an
uncoated bar and, accordingly, L sy.tb
shall be multiplied by 1.5 for
epoxy-coated bars. The tensile strength of lightweight concrete is
significantly less than for normal weight concrete and so the average
ultimate bond stress is also lower. The standard specifies that the basic
development length shall be multiplied by 1.3 when lightweight
concrete is used and when the structural element containing the
deformed bar is built with slip forms.
Refined Development Length
In situations where there is significant transverse reinforcement along
the development length or where there is transverse pressure, the
average ultimate bond stress increases and a reduced development
length may be possible by multiplying the basic development
length L sy.tb
(obtained from Eq. 13.1.2.2) by two factors, k 4
and k 5
.
The factor k 4
(= 1.0 – Kλ) accounts for the presence of transverse
reinforcement and is equal to 1.0 when there is no transverse
reinforcement and may reduce to a minimum value of 0.7 depending
on the amount and location of the transverse reinforcement.
The term λ depends on the total cross-sectional area of transverse
reinforcement along the basic development length (ΣA tr
), as well as
the cross-sectional area of the single anchored bar being developed
(A s
) and is given by λ = (ΣA tr
− ΣA tr.min
)/A s
, where ΣA tr.min
is the
Concrete in Australia Vol 35 No 3 27

TECHNICAL PAPER
cross-sectional area of the minimum transverse reinforcement, which
may be taken as A s
/4.
The factor K is a factor that accounts for the position of the anchored
bar with respect to the transverse reinforcement, where K = 0.1 when
the anchored bar is in the corner of a fitment so that transverse steel
crosses both horizontal and vertical splitting cracks; K = 0.05 when
the transverse steel lies between the anchored bar and the concrete
surface and crosses cover cracking in one direction only (see FIGURE
13.1.2(B)). Otherwise K = 0 and therefore k 4
= 1.0.
The factor k 5
(= 1.0 – 0.04ρ p
) accounts for the increase in the
average ultimate bond stress when transverse pressure (ρ p
in MPa)
exists along the development length perpendicular to the plane of
splitting. As ρ p
increases from zero to 7.5 MPa, k 5
decreases linearly
from 1.0 to 0.7. When ρ p
exceeds 7.5 MPa, k 5
= 0.7.
In addition, a lower limit of 0.7 is set on the product of k 3
, k 4
and k 5
.
When more reinforcement is provided than is necessary for strength
at a particular location and the stress to be developed (σ st
) in a
deformed bar is less than the yield stress (f sy
), the development
length L st
may be reduced proportionally (ie. L st
= L sy.t
σ st
/f sy
) with
an absolute minimum value of 12d b
. This reduction in development
length is not to be applied to the calculation of lap splice lengths.
Only full-strength lap splices are permitted by the Standard.
The minimum value of 12d b
can be reduced for slabs in some
circumstances as outlined in Clause 9.1.3.1 (a)(ii) of the Standard.
The average ultimate bond stress of a plain bar in tension is
significantly smaller than that of a deformed bar and, as a
consequence, the Standard requires that the development length
in tension for a plain bar is 50% longer than for a deformed bar in
the same location.
Illustrative Example
Consider the development length required for the two terminated
28 mm diameter bottom bars in the beam shown in Figure 4. Take
f sy
= 500 MPa; f c
¢ = 32 MPa, cover to the 28 mm bars = 40 mm
and the clear spacing between the bottom bars a = 60 mm. The
cross-sectional area of one N28 bar is A s
= 620 mm 2 and with
N12 stirrups at 150 mm centres, A tr
= 110 mm 2 . In this example:
For bottom bars, k 1
= 1.0;
For 28 mm diameter bars k 2
= (132 – 28)/100 = 1.04;
The concrete confinement dimension, c d
= a/2 = 30 mm, and
therefore
k 3
= 1.0 – 0.15(30 – 28)/28 = 0.99
The basic development length is therefore
05 . ¥ 10 . ¥ 099 . ¥ 500¥
28
L sy.tb
=
= 1178 mm (> 29 k 1
d b
)
104 . 32
The minimum number of stirrups that can be located within the
basic development length is 7. Therefore, ΣA tr
= 7 x 110 = 770
mm 2 . Taking ΣA tr.min
= 0.25A s
= 155 mm 2 , the parameter λ = (770
– 155)/620 = 0.99. From Figure 13.1.2B, K = 0.05 and therefore
k 4
= 1.0 – 0.05 x 0.99 = 0.95.
It is assumed that in this location the transverse pressure
perpendicular to the anchored bar is zero, and hence ρ p
increases
from zero to 7.5 MPa, k 5
= 0.
From Eq. 13.1.2.3:
L sy.t
= k 4
k 5
L sy.bt
= 0.95 x 1.0 x 1178 = 1120 mm.
13.2.2 Lapped splices for bars in tension
This clause applies to both contact lapped splices, where the bars being spliced are in physical contact with each other,
and non-contact lapped splices, where the bars being spliced are physically separated.
In band beams, slabs and walls, where the bars being lapped are in the plane of the band, slab or wall, the lap length for contact and
no-contact splices for bars in tension shall be not less than k 7
L sy.t
, where L sy.t
is calculated in accordance with either Clause 13.1.2.2 or
Clause 13.1.2.3. The factor k 7
depends on the percentage of bars being spliced at the particular location and is given in Table 13.2.2.
In all other situations, the lap length shall be not less than the larger of k 7
L sy.t
and L sy.t
+ 1.5s b
, where s b
is the clear distance
between bars of the lapped splice (mm).
A s
provided/ A s
required
TABLE 13.2.2
Factor k 7
for lapped splices in tension.
Maximum percentage of A s
lapped in section
50% 100%
≥ 2 1.0 1.25
< 2 1.25 1.25
28 Concrete in Australia Vol 35 No 3

Figure 4. Development length of 28 mm bottom bars.
(a) Development Lengths.
(b) Lapped Splice Lengths.
Figure 5. Comparison of requirement for 12 mm bottom bars in slabs ( f c
¢ = 32 MPa).
3.2 Lapped Splice Length for Deformed Bars
in Tension
Wording
The revised wording for the Clause 13.2.2 Lapped splices for bars
in tension is as shown on opposite page.
Discussion
In band beams, slabs or walls, where the bars being lapped are in
the plane of the band, slab or wall, as shown in Figure 2, the lap
length for contact and non-contact splices for bars in tension shall
be not less than k 7
times the development length calculated in
accordance with Clause 13.1.2 or 13.1.3, as appropriate. The factor
k 7
= 1.25 for all lapped splices, except that k 7
may be taken as 1.0
when the splices are staggered so that 50% or less of the bars are
spliced at the same location, as shown in Figure 2b, and when the
splice is located in a region of low tension where the area of steel
is at least double that required (such as near the point of inflection
in a beam or slab).
For non-contact lapped splices, where the clear distance between the
bars of the lapped splice s b
exceeds about 6d b
, and the tensile forces
either side of the splice are non-concurrent, the shear lag effect may
require a longer lap length. In this case, the specified lap length is the
larger of k 7
L sy.t
and L sy.t
+ 1.5 s b
.
4 COMPARISON BETWEEN AS3600-2001
AND THE AS3600-2009
Comparisons are presented here between the minimum development
lengths and lapped splice lengths specified in AS3600-2001 and the
revised provisions of AS3600-2009 for deformed bars acting as tensile
reinforcement (with f sy
= 500 MPa) in the bottom of a beam or slab.
Figure 5 shows the comparisons of development lengths and lapped
splice lengths versus bar spacing for 12mm diameter bottom bars in
a slab (clear cover = 25 mm and f c
¢ = 32 MPa). At a clear spacing
of 150 mm, there is an unrealistic and inappropriate step in the line
representing AS3600-2001 rendering the results unconservative for
wider bar spacings. The results predicted by the revised procedure in
AS3600-2009 have been shown to provide an appropriate level of
safety when compared to the Australian test data for lapped splices in
slabs and are also in good agreement with the ACI318-08 predictions.
Concrete in Australia Vol 35 No 3 29

TECHNICAL PAPER
(a) Development Lengths.
(b) Lapped Splice Lengths.
Figure 6. Comparison of requirement for 28mm bottom bars in beams ( f c
¢ = 32 MPa and N12 stirrups at 150 mm centres).
Figure 6 shows comparison of development lengths and lapped
splice lengths versus bar spacing for 28mm diameter bottom bars
in a beam (with clear cover = 40 mm, f c
¢ = 32 MPa and N12
stirrups at 150 mm centres). The 28 mm bars are assumed to be
in the corner of the stirrups. For the revised Standard, AS3600-
2009, both the simplified approach ignoring the confinement
provided by the stirrups and the refined approach including the
beneficial effects of the stirrups are included. Clearly for bars in
beams at centres less than about 100 mm, AS3600-2001 predicts
conservative development lengths and lapped splice lengths. The
AS3600-2009 approach provides trends (and magnitudes) similar
to the other major codes and is consistent with a wide range of
test data (Gilbert, 2007).
5 CONCLUDING REMARKS
The proposed revision to AS3600 brings the Australian Standard
into line with the test data and the other major international
standards. It is soundly based and easy to use. It is a significant
improvement to the Australian provisions for development of
stress in reinforcing bars in tension.
REFERENCES
American Concrete Institute 2008, “Building code requirements for
structural concrete”, (ACI 318-08). ACI Committee 318. Michigan.
AS1480-1982, “SAA Concrete Structures Code”, Standards
Association of Australia, Sydney.
European Committee for Standardisation [CEN] 2004, “Eurocode
2: Design of concrete structures Part 1-1: General rules for
buildings”, The European Standard EN 1992-1-1:2004. Brussels.
Ferguson, B.J. 1988. Reinforcement Detailing Handbook. Concrete
Institute of Australia.
Gilbert, R.I. 1997, “Anchorage of reinforcement in High
Strength Concrete”, Proceedings, USA-Australia Workshop on High
Performance Concrete (HPC), Sydney, Australia, 20-23 August,
published by Curtin University of Technology, Perth, pp 425-444.
Gilbert, R.I. 2007, “A review and critical comparison of the
provisions for the anchorage of reinforcement in North American,
European and Australian Standards”, Concrete in Australia,
Concrete Institute of Australia, Vol. 33, No.3, October, pp. 33-40.
Gilbert, R.I. 2008, “Experimental Data – Lapped Splice Lengths
for Tensile Reinforcing Bars in Slabs”, Submission to BD-002,
14 th August 2008.
Goto Y 1971. Cracks formed in concrete around deformed tension
bars. ACI Journal, 68(4): 244-251.
O’Moore, L.M. and Dux, P.F. 2009, “Lapped Splices in Reinforced
Concrete Slabs – an Experimental Review of Current and Proposed
Code Revisions” accepted for presentation at Concrete Solutions
09, Concrete Institute of Australia, September, Sydney.
Tepfers, R 1979. Cracking of concrete cover along anchored deformed
reinforcing bars. Magazine of Concrete Research, 31(106): 3-12.
Tepfers, R 1982. Lapped tensile reinforcement splices. Journal of
the Structural Division, ASCE, 108(1): 283-301.
Yates, D. 2008, “The Safety of Design Code Specified Lap Splices
in Reinforced Concrete Slabs”, Bachelor of Engineering Thesis,
University of Queensland.
Yeow, J.X. 2008, “The Development Length and lapped splice
Length in Reinforced Concrete”, Bachelor of Engineering Honours
Thesis, University of New South Wales.
30 Concrete in Australia Vol 35 No 3

TECHNICAL PAPER (PEER REVIEWED)
Restrictions on the use of Class L
reinforcement in AS3600-2009 *
Professor Ian Gilbert
Centre for Infrastructure Engineering and Safety,
School of Civil and Environmental Engineering, The University of New South Wales
SUMMARY: Ductility is a fundamental requirement that underpins the assumptions that are routinely made in the
analysis and design of concrete structures and it is essential for the safety and well-being of the completed structure and its
users. Adequate ductility is necessary for concrete structures to be able to redistribute internal actions and to find the load
paths assumed in design. It is essential if the energy associated with unforeseen impact or seismic loads is to be absorbed
and if large deformations are required prior to collapse. Without ductility, concrete structures are compromised and many
of the advantages of reinforced concrete as a construction material are lost. In lightly reinforced slabs containing Class L
mesh, at the ultimate moment, fracture of the tensile steel occurs well before the concrete in the compression zone becomes
overstressed, certainly well before the extreme compressive fibre strain reaches 0.003 (as specified in AS3600-2001). The
failure is sudden and brittle and the conventional understanding of ductile under-reinforced fl exural failure is not valid.
As a consequence of the loss of ductility that arises when Class L reinforcement is used, various restrictions on its use were
included in AS3600-2001 when it was first released and additional restrictions were introduced in Amendment 2 to
AS3600-2001 in October 2004, including a 20% additional penalty on the strength of members containing Class L
reinforcement. In the revised Standard, these restrictions are restated and clarified. This paper outlines the restrictions on
the use of Class L reinforcement in AS3600 and explains why these restrictions are necessary.
1 INTRODUCTION AND BACKGROUND
In 2001, Standards Australia formally recognised the introduction
of 500 Grade reinforcement (AS/NZS4671-2001 Steel Reinforcing
Materials) and classified it in terms of its ductility – either Class N
normal ductility or Class L low ductility. For each ductility class,
minimum limits were set for the strain at peak stress (or uniform
elongation, ε su
) and the ratio of tensile strength to yield stress (f su
/
f sy
). For Class L reinforcement, these limits were (and still are)
ε su
≥ 1.5% and f su
/f sy
≥ 1.03. These limits are considerably lower
than the corresponding limits set in Eurocode 2 for the lowest
ductility steel permitted in Europe (Class A). In fact, they are
the lowest ductility limits set for any class of steel reinforcement
for use in concrete structures anywhere in the world.
The use of Class L reinforcement in concrete structures has been the
subject of much debate during the development of AS3600. A special
Ad-Hoc Committee was formed by Standards Australia in 2003 to
consider the suitability of Class L reinforcement in suspended slabs
and the restrictions on the use of Class L reinforcement introduced
into AS3600-2001 as part of Amendment 2 (October 2004) were
the result of the findings of that Ad-Hoc Committee.
The problems with low ductility reinforcing steel were recognised
over a decade ago in Europe. Much criticism regarding the ductility
of European Class A reinforcement has appeared in the literature.
* This paper was accepted for publication following peer
review on 7/7/09. © Concrete Institute of Australia, 2009.
In Australia, the situation is considerably worse since the ductility
limits for Class L reinforcement are significantly lower than for
European Class A, and the Australian steel reinforcement industry
promotes the use of Class L in suspended floors.
In his seminal paper on ductility of reinforced concrete (Beeby,
1997), Professor Andrew Beeby observed:
“In particular, reinforcement, which is assumed in the design
to constitute the ties in reinforced concrete structures, must
obviously be highly ductile if the structure is to behave as
envisaged … The reinforcement for structural uses should
result in the formation of a multi-crack hinge. This would
require all reinforcement used structurally to have a ductility
slightly higher than the current high ductility reinforcement.
… To produce multi-crack hinges, a ductility higher than
the current high ductility specification would be necessary.
This conclusion is awkward as it suggests that ductility limits
should be considerably higher than is achieved by significant
amounts of current production.” – A. Beeby (University
of Leeds)
In response to Professor Beeby’s paper (Marti & Alvarez, 1998),
Professor Peter Marti stated:
“We share Professor Beeby’s concerns about recent lowering of
ductility properties of some reinforcing steels … The effect of lower
ductility properties is most severe for cold-deformed and coiled,
small diameter bars and wires which are used predominately
for slab construction” – P Marti (ETH, Zurich)
Concrete in Australia Vol 35 No 3 31

TECHNICAL PAPER
Also in discussion of Beeby’s paper (Morley, 1998), Dr Chris
Morley pointed out the importance of ductility in slab design:
“Whenever one uses a simplified equilibrium system in design
(which people often do), one is relying on the lower-bound
theorem of plastic theory and therefore requiring some ductility.
Whenever you take some simplified equilibrium system for
a slab, you are really relying on plastic design methods and
therefore in need of ductility … some of the steel being provided
is not so ductile as it might be” – C Morley (Cambridge)
When reporting the results of their independent tests on slabs
containing low ductility European reinforcement, Alvarez et al
(2000) concluded:
“The reduced ductility properties of cold-deformed and
coiled small-diameter reinforcing bars and wires may
result in dangerous strain localisations, impairing rotation
capacity, permissible moment redistribution, and ultimate
strength … The reduction of ductility properties is most
pronounced for cold-deformed and coiled small-diameter
reinforcing bars and wires that are predominantly used in
slab construction. It is demonstrated that the corresponding
strain localisation results in a reduced rotation capacity that
may affect the ultimate strength … By keeping up suffi cient
ductility properties of the reinforcing steel, such a change of
well established design practice can be avoided.”
and Eligehausen & Fabritius (1993) observed:
“The CEB relationship could be unsafe. This arose because
some of the types of reinforcement currently used in reinforced
concrete are substantially more brittle than those used in
the CEB tests, and failure could occur by rupture of the
steel at rotations well below the CEB Curve.”
More recently, when referring to the load-deflection curve of
their continuous slab containing Class L reinforcement, Siddique
et al (2008) stated:
“the curve near the maximum load does not reach a plateau,
indicating that the full plastic collapse mechanism is unable
to form before localised failure occurs. The failure itself was
very sudden and brittle resulting from the abrupt snapping
of the top steel reinforcement”
In their paper on the use of low ductility mesh in the design of
suspended concrete slabs, Foster & Kilpatrick (2008) conclude:
“… has shown the high degree of strain localisation that
occurs in high-bond, high-strength welded wire meshes,
particularly those that incorporate small diameter wires.
Rotation tends to concentrate at a single major crack (Beeby
1997a) which results in low rotation capacity and curvature
ductility. Associated curvatures are therefore small, as are
the related defl ections that are almost imperceptible and
provide little warning of failure which is usually sudden
and catastrophic.
Presently this is indirectly addressed in AS3600 which
effectively requires that 20% more fl exural reinforcement
(than that required for Class N steel) is provided. This may
allay concerns arising from design approximations … or the
effects of support settlement, and the requirement should
therefore be retained.”
By contrast, to the writer’s knowledge at the time of writing
this paper, there has not been a single publication in a fully
refereed and peer-reviewed journal that supports the use of
Class L reinforcement in suspended slabs or that is critical of
the current restrictions on the use of Class L reinforcement in
AS3600-2001. It is acknowledged that the Steel Reinforcement
Institute of Australia (SRIA) has recently sponsored a series of
tests on 11 slabs containing Class L reinforcement at Curtin
University of Technology (including one two-way edge-supported
slab), but the results of that test program were not available at
the time of writing.
This report outlines the reasons why the restrictions have been
imposed on the use of Class L reinforcement in reinforced concrete
structures. Most of the restrictions, including the 20% additional
penalty on the strength of members with Class L reinforcement
are already in place in AS3600, having been introduced in
Amendment 2 (October 2004). In effect, there is relatively little
that is new in the draft under consideration here with respect to
Class L reinforcement.
2 THE LACK OF DUCTILITY OF SLABS
CONTAINING CLASS L REINFORCEMENT
Ductility is the ability of a structure or structural member to
undergo large plastic deformations without significant loss of
load carrying capacity.
Figure 1 shows the load-deflection curves for two simply-supported
reinforced concrete one-way slabs tested to failure by Gilbert &
Smith (2004). Curve A indicates the typically ductile behaviour
of a slab containing hot-rolled deformed Class N bars (Slab S8).
Large plastic deformations develop as the peak load is approached.
The relatively flat post-yield plateau (from point 1 to point 2 on
Curve A) where the structure deforms while maintaining its full
load carrying capacity (or close to it) is characteristic of ductile
behaviour. Curve B indicates non-ductile or brittle behaviour
of a slab containing Class L welded wire mesh (Slab S2), with
relatively little plastic deformation before the peak load. There
is little or no evidence of a flat plastic plateau as the peak load is
approached and the slab immediately begins to unload when the
peak load is reached. Slab S2 was tested by controlling the rate of
deformation applied to the slab, so it was able to unload by 17%
prior to fracture of the reinforcement and catastrophic collapse
of the span. Had the slab been tested in load control by gradually
applying increasing load, the slab would not be able to unload and
collapse would occur suddenly when the peak load was reached.
Beeby (1997) first identified the single crack hinges associated with
low-ductility welded wire fabric, where plastic hinge lengths are
typically an order of magnitude smaller than the multi-crack hinges
associated with normal ductility bars. The plastic rotation that can
develop at a plastic hinge depends on the ultimate curvature and
the hinge length. For Class L hinges in one-way members, both
the ultimate curvature and the hinge length are exceedingly small.
The lack of plastic deformation at peak load in Curve B of Figure
32 Concrete in Australia Vol 35 No 3

Applied Load, (kN)
25
20
15
10
5
DUCTILE AND NON-DUCTILE BEHAVIOUR
1
Curve A - Slab S8 (A st /bd = 0.0038 Class N bars) - Ductile
Curve B - Slab S2 (A st /bd = 0.0029 Class L mesh) - Brittle
2
0
0 40 80 120 160 200
Mid-span deflection (mm)
Figure 1. Load vs deflection curves of a ductile and a brittle one-way slab.
1 is typical of the lack of deformation associated with a plastic
hinge in a one-way slab reinforced with Class L steel.
The non-ductile curve B in Figure 1 is typical of the measured
load-deflection responses of over 50 slabs containing Class L
reinforcement tested at UNSW as part of a comprehensive research
project studying the strength and ductility of slabs containing low
ductility steel. The project was funded by the Australian Research
Council in two separate ARC Discovery Projects (DP0210039
and DP00558370) spanning from 2003 to 2009. The results of
this work have been published widely, including in rigorously
refereed international journals. Gilbert & Smith (2004, 2006),
Gilbert et al (2006), Gilbert & Sakka (2007), Sakka & Gilbert
(2008a, 2008b, 2008c, 2008d, 2009) and Smith & Gilbert (2003)
are some of these publications. Sakka & Gilbert (2008a, 2008b,
2008c, 2008d, 2009) provide a comprehensive overview of the
more recent testing and the results obtained in that work. Figure
2 contains a series of photographs of some of the tests specimens
after testing.
Seventeen two-way slabs containing Class L reinforcement have
also been tested. Sakka & Gilbert (2008) contains the results
of eleven corner-supported two-way slab panels. In essence, the
corner supported slabs reinforced with Class L have the same
ductility issues as one-way slabs, collapsing much like a one-way
slab with the steel in one direction fracturing in a single failure
crack across the mid-span region in one direction. However, the
six edge-supported slabs tested at UNSW and reported in Sakka
& Gilbert (2009) were surprisingly deformable. It appears that
slabs reinforced with Class L perform more satisfactorily, as they
become more redundant and there are more possible load paths.
In the edge-supported slabs tested at UNSW, the failure load far
exceeded the yield-line load, as loads were carried by membrane
action and torsion (as well as in bending). There were many
cracks at close centres in the peak moment regions, in contrast to
the single crack hinges that characterise one-way slabs. The slabs
deformed significantly and continued to carry load even after wires
in particular areas fractured. There was no sudden collapse in these
very redundant edge-supported slabs.
Unfortunately, when developing rules for AS3600, one cannot
be sure where Class L reinforcement will be used. It can be used
in cantilevered balconies (where there is no redundancy at all and
just a single load path) and in one-way elements where single
crack hinges result in vary small rotation capacity at the hinge. In
these situations, Class L should not be used. The 20% reduction
in f introduced into AS3600 when Class L reinforcmenet is used
may look after strength, but there are questions still about ductility
and robustness. When subject to an unforeseen overload, there
will still be little warning of failure and the structure will collapse
suddenly – so it will not be robust.
3 THE TREATMENT OF DUCTILITY IN
AS3600-2001 – THE 20% PENALTY WHEN
CLASS L REINFORCEMENT IS USED AND
OTHER RESTRICTIONS
Ductility is important for many reasons, including:
(i) to give warning of incipient collapse by the development of
large deformations prior to collapse;
(ii) to provide reinforced concrete structures with alternative
load paths and the ability to redistribute internal actions as
the collapse load is approached;
(iii) in seismic regions, to enable major distortions to be
accommodated and energy to be absorbed without collapse
during an earthquake; and
(iv) to assist in providing “robustness” (an ability to withstand
unforeseen local accidents without collapse).
Reinforced concrete structures are non-linear and inelastic. The
stiffness varies from location to location depending on the extent
of cracking and the reinforcement layout. In addition, the stiffness
of a particular cross-section or region is time-dependent, with the
distribution of internal actions changing under service loads due to
creep and shrinkage, as well as other imposed deformations such
as support settlements and temperature changes and gradients.
All these factors cause the actual distribution of internal actions
in an indeterminate structure to deviate from that assumed in an
elastic analysis.
Concrete in Australia Vol 35 No 3 33

TECHNICAL PAPER
(a) Simply-supported one-way slab.
(b) Two-span continuous one-way slab.
Figure 2. Brittle collapse of slabs reinforced with Class L mesh.
(c) Corner supported two-way slab.
Despite these difficulties, codes of practice permit the design of
concrete structures based on elastic analysis. This is quite reasonable
provided the critical regions possess sufficient ductility (plastic
rotational capacity) to enable the actions to redistribute towards
the calculated elastic distribution as the collapse load is approached.
If critical regions have little ductility (such as in over-reinforced
elements or when low ductility (Class L) reinforcement is used),
the member may not be able to undergo the necessary plastic
deformation and the safety of the structure could be compromised.
When Class L reinforcement is used in one-way slabs or in twoway
slabs where the degree of redundancy is low, the failure mode
is brittle. Failure occurs suddenly and with little warning by
fracture of the reinforcement at relatively small deformations. The
restrictions on Class L reinforcement in AS3600 are a direct result
of its low ductility and the resulting consequences on the ductility
and failure mode of the structures. The restrictions in fact have very
little to do with the ultimate strength of the member or structure.
In AS3600, ductility is one of the factors that is taken into account
when determining the appropriate strength reduction factor φ for
any particular situation. The commentary to AS3600 (AS3600
Supp1 – 1990) states in Clause C2.3:
“φ varies with the ductility of the section under consideration,
fully ductile behaviour being assigned a value of 0.8 and,
non-ductile behaviour, a value of 0.6.”
When this was written in 1990, under-reinforced slabs were
considered “fully ductile” with φ = 0.8. Reinforcement was assumed
to be elastic/perfectly plastic. No-one had yet contemplated using
brittle reinforcement that fractured well before the compressive
concrete had even become overstressed. Over-reinforced members
were considered non-ductile with φ = 0.6.
34 Concrete in Australia Vol 35 No 3

In accordance, with this general philosophy, the non-ductile
behaviour that results from the use of Class L reinforcement in
under-reinforced slabs has been treated by reducing the strength
reduction factor by 20% from 0.8 to 0.64. The lack of ductility
associated with over-reinforced members is treated by reducing
φ by 25% from 0.8 to 0.6. Considering that the failure of a member
containing Class L steel by fracture of the tensile reinforcement is
sudden and catastrophic, and usually occurs at a smaller deformation
than the more gradual failure of an over-reinforced member, the
20% penalty on the use of Class L reinforcement is rather lenient
and there is a strong argument for it to be increased to 25%.
The rotation capacity of plastic hinges in members containing
Class L reinforcement is generally too small to permit the use of
plastic methods of analysis and design or such other simplified
methods of analysis that require very substantial redistribution
(such as the idealised frame method). As a consequence, AS3600
does not permit the use of Class L reinforcement when any plastic
design methods are adopted, including strut and tie modelling,
yield line design, the strip method of slab design and simplified
lower bound approaches, such as the idealised frame method or
the direct design method of analysis. The idealised frame method
involves modelling a two-way slab as a series of one-way frames.
The moments so determined are then assigned by the designer to
column and middle strips. The code allows a wide range of values
for the fraction of the frame moment assigned to the column strip.
It is an approximate method of analysis (in fact, it represents a
lower bound plastic solution) that only works if the structure is
designed with ductile reinforcement and if the structure possesses
the ductility required to find the load path assumed in design.
With Class L reinforcement, the required ductility may not be
available – it certainly is not available with reinforcement that only
just satisfies the minimum ductility limits accepted in Australia
for Class L steel (ε su
≥ 1.5% and f su
/f sy
≥ 1.03).
Clause 1.1.2c in the revised Standard states that Class L steel “shall
not be used in any situation where reinforcement is required to undergo
large plastic deformation under strength limit state conditions”. This
statement is clear and unambiguous. When the design assumptions
are such that the reinforcement is required to undergo large plastic
deformation at the strength limit state, then Class L reinforcement
must not be used because it is simply unable to do so.
If one requires robustness and the ability to absorb energy associated
with impact or dynamic load or if one simply wants a floor when
overloaded not to collapse by fracture of brittle reinforcement at a
single crack hinge, Class L reinforcement must not be used. Class L
may be used in situations where the reinforcement is not required
to deform appreciably (eg. crack control) or in rare situations where
the steel is required for strength but not ductility.
A similar clause is already in the Standard, but the wording has been
changed. The existing Clause prohibits the use of Class L “where
the reinforcement is expected to undergo large deformation”. It was
argued that as Class L is brittle then one would never expect it to
undergo large deformations. The wording has been changed quite
deliberately to prohibit the use of Class L reinforcement “where
the reinforcement is required to undergo large deformation”.
The statement in Clause 17.2.1.1 of the revised Standard to the
effect that “Class L reinforcement shall not be substituted for Class
N reinforcement unless the structure is redesigned” is a sensible and
seemingly obvious inclusion in the Standard. The selection of
the Ductility Class for reinforcement is an important and far
reaching design decision. It must not be able to be changed without
considering the full design implications or without knowledge of
the original design assumptions.
4 CONCLUDING REMARKS
The restrictions and penalties on the use of Class L reinforcement
in the revised Standard AS3600-2009 are based on sound scientific
arguments relating to the design requirement for ductitily. The
20% penalty on strength reflects the adverse impact of Class L
reinforcement on structural ductitily. The penalty will clearly
have an economic impact on the cost of concrete structures if
Class L reinforcement is used. However, if the minimum ductility
limits for Class L reinforcement in AS/NZS4671 were increased
substantially, then perhaps in time the 20% penalty could be
reviewed. At present, with the industry supporting and insisting
on the lowest ductility limits in any international Standard (ε su
≥ 1.5% and f su
/f sy
≥ 1.03), the 20% penalty must be maintained
and the elimination of the penalty (and the other restrictions)
would compromise the safety of reinforced concrete structures
in Australia. In fact, there is a strong argument that the penalty
should be 25% to be consistent with the phi factors imposed in
the Standard on other similarly brittle failure modes.
ACKNOWLEDGEMENT
The support of the Australian Research Council in the form of
an Australian Professorial Fellowship awarded to the writer is
gratefully acknowledged.
REFERENCES
Alvarez, M., Koppel, S. and Marti, P. 2000, “Rotation Capacity
of Reinforced Concrete Slabs”, ACI Structural Journal, Vol. 97,
No.2, pp 235-242.
Beeby, A.W. 1997, “Ductility in Reinforced Concrete: Why is it
Needed and How is it Achieved”, The Structural Engineer, Vol.
75, No.18, pp 311-318.
Eligehausen, R. and Fabritius, E. 1993, “Tests on continuous slabs
reinforced with welded wire mesh”, CEB Bulletin d’Information No.
218, Ductility Requirements for Structural Concrete – Reinforcement,
Task Group 2.2, Comité Euro-International du Béton, Lausanne,
pp 133-148
Foster, S.J and Kilpatrick, A. 2008, “The use of low ductility
welded wire mesh in the design of suspended reinforced concrete
slabs”, Australian Journal of Structural Engineering, Vol. 8, No. 3,
pp 237-247
Concrete in Australia Vol 35 No 3 35

TECHNICAL PAPER
Gilbert, R.I., Sakka, Z.I. and Curry, M. 2006, “The Ductility of
Suspended Reinforced Concrete Slabs containing Class L Welded
Wire Fabric”, Keynote paper, Proc., 19 th Australasian Conf. on
the Mechanics of Structures and Materials (ASMSM19), Univ. of
Canterbury, Christchurch, New Zealand, Nov., Taylor and Francis,
London, Moss P.J. and Dhakal R.P. (Eds), pp. 3-12.
Gilbert, R.I. and Sakka, Z.I. 2007, “The effect of reinforcement type
on the ductility of suspended reinforced concrete slabs”, Journal of
Structural Engineering, American Society of Civil Engineers (ASCE),
Vol. 133, No. 6, pp 834-843.
Gilbert, R.I. and Smith, S.T. 2004, “Strain localization and its
impact on the ductility of reinforced concrete slabs containing 500
MPa reinforcement”, Proceedings, The 18th Australasian Conference
on the Mechanics of Structures and Materials (ASMSM18), University
of Western Australia, Perth, December, pp 811-817.
Gilbert, R.I. and Smith, S.T. 2006, “Strain localization and its
impact on the ductility of reinforced concrete slabs containing
welded wire reinforcement”, Journal of Advances in Structural
Engineering, Vol. 9, No. 1, February, pp 117-127.
Marti, P. and Alvarez M. 1998, “Ductility in Reinforced Concrete:
Why is it Needed and How is it Achieved”, Discussion, The
Structural Engineer, Vol. 76, No. 9, pp 181-182.
Morley, C.T. 1998, “Ductility in Reinforced Concrete: Why is
it Needed and How is it Achieved”, Discussion, The Structural
Engineer, Vol. 76, No. 9, pp 182.
Sakka, Z.I. and Gilbert, R.I. 2008a, “Effect of Reinforcement
Ductility on the Strength and Failure Modes of One-way Reinforced
Concrete Slabs”, UNICIV Report No. R-450, School of Civil and
Environmental Engineering, The University of New South Wales,
Sydney.
Sakka, Z.I. and Gilbert, R.I. 2008b, “Effect of Reinforcement
Ductility on the Strength, Ductility and Failure Mode of
Continuous One-way Concrete Slabs Subjected to Support
Settlement – Part 1”, UNICIV Report No. R-451, School of Civil
and Environmental Engineering, The University of New South
Wales, Sydney.
Sakka, Z.I. and Gilbert, R.I. 2008c, “Effect of Reinforcement
Ductility on the Strength, Ductility and Failure Mode of
Continuous One-way Concrete Slabs Subjected to Support
Settlement – Part 2”, UNICIV Report No. R-452, School of Civil
and Environmental Engineering, The University of New South
Wales, Sydney.
Sakka, Z.I. and Gilbert, R.I. 2008d, “Strength and Ductility of
Corner Supported Two-way Concrete Slabs Containing Welded
Wire Fabric”, UNICIV Report No. R-453, School of Civil and
Environmental Engineering, The University of New South Wales,
Sydney (ISBN: 85841 420 1).
Sakka, Z.I. and Gilbert, R.I. 2009, “Ductility of edge-supported
two-way concrete slabs containing Class L reinforcement”,
UNICIV Report No. R-454, School of Civil and Environmental
Engineering, The University of New South Wales, Sydney.
Siddique, U., Goldsworthy, H. and Gravina R.J. 2008, “Behaviour
of One-Way Continuous Reinforced Concrete Slabs – constructed
with grade 500 Class L mesh steel, under support settlement”,
Concrete in Australia. Vol. 34, No.1, pp. 39-42.
Smith, S.T. and Gilbert, R.I. 2003, “Tests on RC slabs reinforced
with 500 MPa welded wire fabric”, Australian Journal of Civil
Engineering, Institution of Engineers, Australia, Vol. 1, No. 1,
pp 59-66.
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36 Concrete in Australia Vol 35 No 3

Stress, c (MPa)
TECHNICAL PAPER (PEER REVIEWED)
Detailing of High Strength Concrete
Columns to AS3600-2009 *
Professor Stephen Foster, Centre for Infrastructure Engineering and Safety
School of Civil and Environmental Engineering, The University of New South Wales
SUMMARY: This paper presents the background to the development of the confinement to the core provisions for
high strength reinforced concrete columns to AS3600-2009. The technical principle behind the rules development is
that, for structures in regions of low and moderate levels of seismicity, a similar level of ductility be maintained for
columns and structures fabricated from high strength concrete to that of columns fabricated from conventional strength
concretes that we know to perform satisfactorily from our long experience. The application of the rules is discussed
and demonstrated through the provision of some examples.
1 INTRODUCTION AND BACKGROUND
Robustness and ductility are important issues when it comes
to the detailing of all-concrete members and columns are no
exception. However, extra attention is required in the detailing of
the tie reinforcement in high strength concrete (HSC) columns
due to the more brittle nature of the concrete with increasing
strength, as seen in Figure 1.
In 1993, the former chairman of BD2, John Webb, wrote:
“The current ACI and AS3600 tie requirements
address only the problem of buckling of longitudinal
reinforcement and can be shown [only] to have a small
effect in confining the column’s concrete core. A much
more ductile column can be provided by increasing the
volume of ties in a column ... Therefore it seems logical
that an increased strength-reduction factor would be
appropriate if additional ties were provided to a normal
strength column. This logic can be followed through for
high-strength columns, attempting to provide comparable
ductility for the same factor ...
Code authors have a number of options to provide a
suitable design method for high-strength columns:
(a) Determining an appropriate strength reduction factor
for use with high strength concrete. This may need
to vary with strength, and be less than the current
factors, eg., 0.6 in AS3600.
(b) Determining an appropriate amount of ties that
would be required to provide comparable ductility
to that provided by the existing tie requirements for
50 MPa (7500 psi) concrete.” Webb (1993).
This is the approach followed in AS3600-2009. Where sufficient
sectional strength is provided, no additional detailing is required
and this is handled by adopting a threshold for where core
* This paper was accepted for publication following peer
review on 5/7/09. © Concrete Institute of Australia, 2009.
120
100
80
60
40
20
40 MPa
20 MPa
100 MPa
80 MPa
60 MPa
0
0 0.002 0.004 0.006
Strain, c
Figure 1. Typical stress versus strain curves for plain concrete.
confinement is required to be considered in detail by the designer.
Where the stresses in the member are sufficiently high, additional
detailing requirements are specified to ensure a similar level of
sectional ductility is achieved as that of historic experience.
Additional detailing requirements are also needed to ensure
that construction of HSC columns meets with the earthquake
requirements as specified in Appendix C of the Standard and
with AS1170.4-2007. Specifically, Appendix C of AS3600-2009
requires that:
“Concrete structures and members shall be designed and
detailed depending on the value adopted for the structural
ductility factor (μ) as follows:
(a) For μ ≤ 2 designed and detailed in accordance with
the main body of this Standard.
(b) For 2 < μ ≤ 3 designed and detailed in accordance
Concrete in Australia Vol 35 No 3 37

TECHNICAL PAPER
(b)
Effectively
confined
core
Cover
Poorly
confined
core
(c)
(a)
Figure 2. Effectively confined area in tied concrete columns; a) square and b) circular sections; c) 3D view of a square column.
with the main body of this Standard and this
Appendix, as appropriate.”
The standard meets the above demands through two provisions.
Firstly, a sufficient level of detailing in critical regions to ensure
that sufficient warning of distress is provided through excessive
deflections, cracking, etc; and, secondly, with a penalty for nonductile
elements through provisions in the strength reduction, φ,
factors (for example φ = 0.8 for beams and φ = 0.6 for columns).
While many definitions/measures for ductility exist, that adopted
in the development of the standard is the I 10
index, where I 10
is
calculated similar to that set out in ASTM C1018 (1992) for
the measurement of toughness. In the context of ductility, the
I 10
parameter is the area under the load versus strain curve at a
strain of 5.5 times the yield strain, relative to the area under the
curve for a strain equal to the yield strain and where the yield
strain is taken as 1.33 times the strain corresponding to a load on
the ascending curve of 0.75P u
(Foster & Attard, 1997). The area
under the load versus strain curve up to 5.5 times the yield strain is
chosen such that for a perfectly elasto-plastic material I 10
= 10 while
for a perfectly elastic-brittle material I 10
= 1. In moving towards
the use of higher strength concretes, the design philosophy is to
maintain a certain minimum level of ductility consistent with that
inferred by the minimum detailing provisions of previous standards
and this is taken as an I 10
value of 5.6, with I 10
= 5.6 being the
assessment of the ductility of a 50 MPa column with minimum
confinement as provided by the 2001 standard. To maintain this
limit, more effort is required in detailing of the lateral confining
reinforcement in the hinge regions in HSC column sections. For
the purposes of historical record, one of the compromises in the
final drafting of the 2009 standard was the requirement in the
draft code (DR05252-2005) for an effective confining pressure
on the core in critical regions of 0. 015 f c
¢ (equivalent to I 10
= 6.5)
be reduced to 0. 010 f c
¢ .
Ductility in columns is derived from confinement provided by
the tie reinforcement to the core and is a function of the yield
strength of the ties, the concrete strength, the volumetric ratio of
tie reinforcement and the arrangement of the ties. The effect of tie
arrangement on providing confinement to the column’s core and,
hence, on ductility of the section, is shown in Figure 2.
A number of authors (Martinez et al, 1984; Bjerkeli et al, 1990;
Sugano et al, 1990; Razvi & Saatcioglu, 1994) have indicated that
ductility is a function of the confinement parameter r s f sy. f f c ¢
where ρ s
is the lateral reinforcement volumetric ratio, f sy. f
is the
yield strength of the tie reinforcement and f c
¢ is the concrete
strength. Razvi & Saatcioglu (1996) suggested that this parameter
be multiplied by a second parameter representing the efficiency of
the tie reinforcement arrangement. For circular and rectangular
sections the efficiency of the confining steel is given by Eqs. 1
and 2, respectively.
For circular columns with tie or spiral reinforcement, assuming
a parabolic arch between the ties with a 45-degree tangent slope
(following the concept advanced by Sheikh & Uzumeri, 1982),
38 Concrete in Australia Vol 35 No 3

d
2
A
btie
. fitf
f
sy sy . f.
f
frf
r
d
s
s
(a)
24A
b.
tie fitff
sy sy.
. ff
frf
r
b
c
s
(b)
y
Y
A
f
b.fit sy.f
d c
fr.yy
b
c
x
Y
2 Ab. fit fsy.
f 1
sin
fr
bc
s
(c)
X
f
r.xx
X
A f
b.fit sy.f
(d)
Figure 3. Calculation of confining pressures for some common section types.
the confinement effectiveness factor is
k
e
2
*
Ê s ˆ
= Á 1 -
Ë 2 d
˜
¯
s
where s * is the clear spacing between the ties or spirals as used
by Mander et al (1988) and d s
is the diameter of the tie or spiral
reinforcement. In the design model s * in Eq. 1 is replaced by the
centre to centre spacing between ties, s.
For square or rectangular sections a modified form of the Sheikh &
Uzumeri (1982) model is used with the confinement effectiveness
parameter given by
k
e
Ê 1
= Á 1 -
Ë 6A
c
n
Â
i=
1
w
2
i
* *
ˆ s s
˜
¯
¥ Ê
Á
Ë
-
ˆ Ê ˆ
1
b
˜ 1 - 2
Á
¯ Ë 2 d
˜
¯
c
c
(1)
(2a)
where w i
is the ith clear distance between adjacent tied longitudinal
bars, b c
and d c
are the core dimensions to the centreline of the ties
across the width and depth of the section, A c
= b c
d c
and n is the
number of spaces between tied longitudinal bars (and equals the
number of tied bars).
In the adopted model, Eq. 2a is simplified to
k
e
Ê nw
= Á 1 -
Ë 6A
2
ˆ Ê s s
¯
˜ -
ˆ Ê
Á
Ë b ¯
˜ -
ˆ
1 Á 1 2 Ë 2 d
˜
¯
c c c
(2b)
where n = number of tied longitudinal bars and w = average clear
spacing between adjacent tied longitudinal bars.
The relationship between the ductility index and the effective
confinement parameter is given in Foster & Attard (2001) as
( )
I10 I = 1. 9ln 1000 k r f f¢
or k r f f¢ = 1.
7 1000 (3)
10 e s sy.
f c e s sy. f c
The confining pressure applied to a section is obtained by cutting
the section and applying statics across the section, as demonstrated
for some common cases in Figure 3.
For a rectangular column (Figure 3d) the confi ning pressure
applied to the section is
f
rxx .
n A f
ly b. fit sy.
f
= f
bs
c
ryy .
nA f
=
ds
c
lx b. fit sy.
f
where f r.xx
is the confining pressure applied to a cut on the x-x
plane (Figure 2d), f r.yy
is the confining pressure applied to a cut
on the y-y plane, n lx
and n ly
are the number of tie legs in the x
(4)
Concrete in Australia Vol 35 No 3 39

TECHNICAL PAPER
DESIGN AXIAL FORCE
N uo
N uo
Region where the design action
effects of combined axial force
and bending on a section require
confinement to the core
N u
0.3A g f c'
M u
M u
DESIGN MOMENT
M uo
Figure 4. Application of confinement AS3600-2009 Cl. 10.7.3 for high strength concrete.
Mu
M 1
*
1.2D
special confinement
region
D
Mu
M 2
*
1.2D
special confinement
region
Figure 5. Special confinement region for a HSC column in double curvature.
and y directions, respectively, and A b.fit
is the cross-sectional area
of a single tie leg.
For rectangular sections, the volumetric ratio of the ties is given by
( )
A n d + n b
b.
fit ly c lx c
r s
=
bds
c c
For symmetrically reinforced square columns and for rectangular
columns with f rx
= f = f , rearranging Eq. 4 and substituting
ry r
into Eq. 5 gives
f
= 05 . r f
(6)
.
r s sy f
It can be shown without difficulty that Eq. 6 is equally applicable
(5)
for the case of circular sections with circular ties or spiral
reinforcement. For sections where f rx
≠ f ry
the confining pressure
can conservatively be taken as f r
= min ( f f ).
r.xx, r.yy
By Eq. 6, the effective confining pressure applied by steel ties on
the core of a reinforced concrete column (at the point of yielding
of the ties) can be written in the form
kf= 05kr f
(7)
.
e r e s sy.
f
where for the purposes of Eq. 7 it is assumed that f r.xx
≈ f r.yy . Lastly,
substitution of Eq. 7 into Eq. 3 leads to
kf
e
r
I10
= 1. 7 f¢
2000
(8)
c
As noted above, AS3600-2001 has an implied level of ductility
40 Concrete in Australia Vol 35 No 3

A B C D E
8.0 m 8.0 m 8.0 m 8.0 m
1
2
3
4
5
6
8.0 m 8.0 m 8.0 m 8.0 m 8.0 m
Figure 6. Floor plan for design examples 3.1 and 3.2.
for columns derived from the detailing requirements of the ties.
An evaluation of the studies by Ghazi (2001) and Zaina (2005)
indicate a level I 10
= 5.6 for a 50 MPa column fabricated to the
minimum detailing requirements of the standard. Maintaining
a similar level of ductility for HSC columns dictates that more
stringent design rules are required for HSC columns than for
conventional strength columns.
Taking I 10
≥ 5.6 as a sufficient level of ductility in non-seismic
regions gives an effective confining pressure requirement of
kf
= 001 . f¢
(9)
e r c
Note that higher values are required for seismic regions where the
ductility index requirement as obtained from AS1170.4 is such
that μ > 3.
2 APPLICATION
Design for confinement to the core of columns is required in a
section that fails in a primary compression mode and is subjected
to high stress. That is in dominantly compression regions where
plastic hinges are required to form. Research by Mendis &
Kovacic (1999) has shown that where the axial force on a section
is less than 0. 3fA
c
¢ g
, no special provisions are needed to obtain a
sufficiently ductile section for non-seismic design over and above
those detailed for restraint of the longitudinal reinforcement. In
addition, no additional provision for tie or helix reinforcement
is required over and above that required for restraint of the
longitudinal reinforcement where the bending stress in the section
is less than 60% of the capacity of the section. The application of
AS3600-2009 clause 10.7.3 is summarised in the M-N interaction
plot shown in Figure 4. In the unhatched regions, the section
stresses, or confinement demands to ensure an adequate level of
ductility, are sufficiently low that no additional attention is needed
other than limits on the spacing of the tie reinforcement. This
limit is that the spacing of the ties or helix reinforcement shall
not exceed the lesser of 0.8 times the depth of the section in the
direction of the bending being considered and 300 mm. For design
action effects on a section that lie within the hatched region,
ties or helix reinforcement is provided such that the minimum
effective confinement pressures are provided on the section at the
strength limit state and with the maximum tie spacing the lesser
of s ≤ 0.6D and 300 mm, where D is measured with consideration
to the axis of bending being considered.
Additionally, to ensure that fitments are placed at a sufficient length
along the member from the centre of the expected plastic hinge, the
fitments are required to extend a minimum length measured each
side of the maximum moment bounded by the lesser of (Figure 5):
(i) 1.2 times the dimension of the cross-section measured
normal to the axis of bending being considered, and
(ii) the distance to the end of the member.
3 DESIGN EXAMPLES
3.1 Example 1: High axial load with low moment
In this first example, two columns from a 20 storey building having
the floor plan shown in Figure 6 are designed and detailed for a
case of gravity loading. The column considered is B2 at Level 1 of
the structure, which is subject to high axial load and low moment.
For the columns we shall take f c
¢ = 80 MPa, f sy. f
= 500 MPa and
Concrete in Australia Vol 35 No 3 41

TECHNICAL PAPER
700
576
25000
20000
Column B2-L1
700
576
Nu (kN)
15000
10000
Section-Core
Confinement
Region
5000
A b.fit fsy.f
f r
0
0 500 1000 1500 2000 2500
Mu (kN)
(a)
(b)
Figure 7. (a) Section for Column B2 Level 1 and (b) section interaction diagram.
a clear cover of 30 mm.
For the case of the Level 1 column, an analysis of the structure gives
the design axial load as N* = 16,700 kN and the design bending
moment to be governed by the minimum eccentricity requirements
such that M* = 0.05DN* = 585 kNm. After consideration of the
stress resultants, a 700 mm square section is selected with 12N40
longitudinal bars, as shown in Figure 7a. The φ-reduced interaction
diagram for the section is shown in Figure 7b.
Plotting of the stress resultant on Figure 7b shows that the member
response is dominated by the axial load, typical of base columns
in high rise structures where wind load is predominantly carried
by shear walls. In this case, the entire length of the member falls
within the definition of a “special confinement zone” and the stirrup
spacing is determined as follows:
Step 1: Calculate the confining pressure via cutting the section
as shown in Figure 6a and trying N12 fitments:
Step 2:
b
f
c
r
= d = 700 - 2( 30)- 12 = 628 mm
c
4 A f
b fit sy f
= ¥ . . 4
= ¥ 110 ¥ 500 350
= MPa
b s 628s s
c
Calculate the confinement effectiveness factor:
w = ÈÎ 700 -2( 30) -2( 12) -4( 40) 3 = 152 mm
A
= b d = 628 ¥ 628 = 394. 4 ¥ 10 3 mm 2
c c c
2
s
k = Ê
- 12 ¥ 152 ˆ Ê
e Á
Ë ¥ ¥ ¯
˜ Ë
Á - ˆ
1
1
3
6 394.
4 10 2 ¥ 628 ¯
˜
2 2
Ê s ˆ
= 0.
883 1 -
Ë
Á 1256 ¯
˜
Step 3: Calculate fitment spacing for kf= 001 . f¢ = 08 . MPa:
e r c
2
Ê s ˆ 350
0. 8 = 0. 883 1 -
...... 24
Ë
Á 1256 ¯
˜ ¥ gives s
s
£ 9mm
maximum spacing limitation of 0.6D and 300 mm ...
gives s ≤ 300 mm.
For the detailing of the fitments, we shall adopt N12 ties, arranged
as shown in Figure 7a, at a spacing of 240 mm through the length
of the column. Note that the solution to the confinement to the
core is that of a quadratic with solutions is provided in Appendix
A for common sections.
3.2 Example 2: Significant axial load
and significant moment
In this second example we design column B2 at Level 15 of
the framed structure of Example 1 and again we shall take
f c
¢ = 80 MPa, f sy. f
= 500 MPa and a clear cover of 30 mm. The
length of the column between the lower slab surface and the
upper slab soffit is 3200 mm.
For the case of the Level 15 column, an analysis of the structure
gives the design axial loads and bending moments shown in
Figure 8. After consideration of the stress resultants, a 350 mm
square section is selected with 8N20 longitudinal bars and with
only the four corner bars tied to the cross section, as shown in
Figure 9a. The φ-reduced interaction diagram for the section is
shown in Figure 9b.
For the detailing of the section, we shall try 2 legged N10 fitments
as shown and, thus, while the total number of bars N = 8, the
number of tied bars in Eq. 2b is n = 4. The calculation procedure
is similar to that of the previous example and for an effective
confining pressure kf= 001 . f¢ = 08 . MPa, we find that b
e r c
c
= d c
42 Concrete in Australia Vol 35 No 3

N* = 2770 kN
M = 225 kNm
2 *
0.19L
139 kNm
N10@120
N10@280
fitment
spacing
AFD
139 kNm
M 1
*
BMD
N10@120
Figure 8. Axial force and bending moment diagrams for column B2 level 15.
350
250
6000
Column B2-L15
5000
4000
Section-Core
Confinement
Region
350
250
Nu (kN)
3000
2000
1000
A b.fit fsy.f
f r
0
0 50 100 150 200 250
Mu (kN)
(a)
(b)
Figure 9. (a) Section for Column B2 Level 15 and (b) section interaction diagram.
= 280mm, w = 230 mm, f r
= 286/s, k e
= 0.55 0 (1–s/560) 2 ) and
s ≤ 120mm (also s ≤ 0.6D = 210mm).
For detailing of the ties for the axial load of 2770 kN, the
maximum design bending moment is equal to φM u
= 231kNm
(Figure 9b). Given that f03 . A f¢ £ N* < f075
. N , confinement
g c uo
reinforcement is required in the region of the member where the
*
section moment, M s*
, is such that M s
0.
6 ¥ 231 = 139 kNm.
This represents a length of column below the upper slab soffit of
the greater of:
Ê M
Á
Ë
*
2
- 06 . fM
ˆ
u
L 225 139 320
*
M ¯
˜ ¥ 2
= Ê - ˆ
Ë
Á
225 ¯
˜ ¥ 0
2
2
= 0. 19L = 610 mm and
1.2D = 420mm.
A similar calculation is undertaken to determine the “special
confinement region” for the column above the lower slab surface
(with M 2*
replaced with M 1*
). Between the confinement regions
the fitment spacings are increased to the limits of 0.8D = 280 mm
(see Figure 8) and 300 mm (clause 10.7.3.1 of the standard) and
15d b
= 15×20=300mm (clause 10.7.4.3 of the standard).
3.3 Example 3: Reinforced concrete
pile in single curvature
In this final example, we consider a circular pile with the
following properties:
1. 720 mm diameter,
2. 100 mm cover,
3. reinforced with 5N24 bars longitudinally,
4. helically reinforced with N12 reinforcement and
5. concrete strength of 70 MPa.
and subjected to the axial force and moment distributions shown
in Figure 10. The piling code (AS2159) requires that where a
bending moment exists, the pile be designed in accordance with the
Concrete in Australia Vol 35 No 3 43

Axial Force (kN)
TECHNICAL PAPER
10000
800
special confinement
region
Bending Moment (kNm)
8000
6000
4000
600
400
580 kNm
2000
0
0 2 4 6 8 10 12 14 16 18 20
Depth (m)
(a)
200
2.3 m
0
0 1 2 3 4 5 6 7 8
Depth (m)
(b)
Figure 10. Axial force and bending moment diagrams for RC pile example.
principles of AS3600. Below the level where the bending moments
become zero, the pile may be designed as an unreinforced section.
The interaction diagram for the circular section is shown in Figure
11. From the interaction plot, it is seen that for the maximum design
axial force of N* = 9100 kN, confinement reinforcement is to be
designed in the sections where M* ≥ 580 kNm. For the circular
section, the confining pressure on the section is calculated as shown
in Figure 3a and the maximum pitch determined as follows:
Step 1: Calculation of the confining pressure via cutting the
section as shown in Figure 3a and for N12 fitments:
d s
= 720 - 2( 100)- 12 = 508 mm
2 A f
b fit sy f
f = ¥ . . 2
= ¥ 110 ¥ 500 217
= MPa
r
d s 508s s
s
Step 2: Calculate the confinement effectiveness factor:
k
e
Ê s ˆ s
= Á -
Ë d ¯
˜ = Ê
Ë
Á - ˆ
1 1 2 1016˜
¯
s
2 2
Step 3: Calculate fitment spacing for k f
2
= 001 . f¢ = 07 . MPa:
e r c
Ê s ˆ 217
07 . = 1-
...... 200
Ë
Á 1016 ¯
˜ ¥ gives s
s
£ mm
maximum spacing limitation of 0.6D and 300 mm ...
gives s ≤ 300 mm.
The special confinement region is determined from the maximum of:
1. where the bending moment on the section is less than
0.6φM u
= 580 kNm and is at a depth of 2.3 metres (Figure
10b); and
2. a distance of 1.2D = 860 mm each side of the section corresponding
to the maximum moment. In this example the maximum moment
is 670 kNm and occurs at depth of 1.22 metres and, thus, the
confinement reinforcement must extend beyond the depth of 2.08
metres and, thus, requirement 1. governs.
Thus, we shall adopt a N12 helix at a pitch of 200 mm to a
depth of 2.3 metres. From a depth of 2.3 metres until the limit of
the reinforcement, the pitch maybe increased to the lesser of the
limit of 0.8D and 300 mm (clause 10.7.3.1 of the standard) and
15d b
= 15×24=360mm (clause 10.7.4.3 of the standard).
4 CONCLUDING REMARKS
This paper presents the background to the development of the
confinement to the core provisions as presented in clause 10.7.3 of
AS3600-2009, together with some design examples. Some changes
were made post the Public Review Draft of the standard released
in 2005 to address some issues raised and to clarify the regions of
members where the additional detailing rules are to be applied.
The technical principles behind the rules development is that a
similar level of ductility be maintained in columns and structures
fabricated from HSC to that in columns fabricated from conventional
strength concretes that we know to perform satisfactorily from our
long experience. The reasons for this are two-fold:
1. Ductility of structures is an important aspect of design and as there
is limited experience in the behaviour of structures constructed
with HSC and member ductility should not be reduced beyond
our experience.
2. In the earthquake standard of the time of the drafting of the core
confinement provisions (AS1170.4-2003), seismic design did
not need to be considered for Category A structures provided
that they be “ductile” as defined in that standard. The rules were
drafted to satisfy this condition. Under the current earthquake
code, AS1170.4-2007, similar provisions are needed in AS3600 so
that the structural ductility factor (μ) is not less than 2 for ordinary
moment resisting frames (OMRFs). In this case, the additional
attention to detailing of the critical sections of HSC columns is
required to ensure that this minimum condition is met.
It will not go unnoticed that additional detailing is required for the
44 Concrete in Australia Vol 35 No 3

16000
14000
12000
Phi reduced
720 dia. Circ.
f'c = 70 MPa
5N24
cover = 100 mm
N12 ties
Nu (kN)
10000
8000
6000
4000
No confinement
needed for sections
in this region
9100 kN
confinement
region bounds
2000
0
0 200 400 600 800 1000 1200
Mu (kNm)
Figure 11. φ-reduced M-N interaction diagram for reinforced concrete pile example.
case of 65 MPa concrete columns over and above those of the 2001
standard. It is important here to recognise that the test data used to
justify the provisions of the previous editions of the standard were
largely adopted from ACI-318 and that these rules were established
from the tests of Hognestad (1951) where the concrete strength did
not exceed 40 MPa. The extension to 50 MPa was already beyond
the test data from which the rules were established and, thus,
the confinement provisions are extended to the case of columns
constructed of 65 MPa concrete in the 2009 revision.
Lastly, this paper has only dealt with the design for fitments for
the provision of confinement to the core in HSC columns. The
designer must also pay due consideration to other design provisions
in the standard that require dimensioning of fitments such as, for
example, the design for shear and for restraint of longitudinal bars
against buckling. In some circumstances these other design conditions
may require closer spacing, or greater areas of reinforcement or
variations of the detailing of the fitments than that of Clause 10.7.3
of AS3600-2009 relating to confinement of the core.
5 APPENDIX
For a rectangular section with a width of core b c
and depth of core
d c
, the solution to the spacing of fitments equation may be solved
as follows (Beletich, 2008):
2
s= ( b + d + R)- ( b + d + R) - 4 b d
(A1)
where
c c c c c c
f b d
c c c
R = ¢
PQ
(A2a)
2
nw
P = 1 -
6A c
(A2b)
È nA f n A f
lx b. fit sy. f ly b. fit sy.
f
Q = min Í ,
ÎÍ
b d
c
c
(A2c)
where n lx
is the number of ties cutting a section taken through
the width of the section and n ly
is the number of ties cutting a
section taken through the depth of the section. For the case of a
symmetrically reinforced square section, Eq. A1 becomes
( ) -
2
2
c c c
s= 2b + R- 2b + R 4b
(A3)
For the case of a diamond tie arrangement (Figure 3c), the values of
n lx
and n ly
in Eq. A2c are replaced with the equivalent component
acting normal to the direction of the cutting plane. Lastly, for a
circular section take P = 1 in Eq. A2b and replace b c
with d s
in
Eqs. A2 and A3.
REFERENCES
AS3600, (2009). “Concrete Structures Code”, Standards Association
of Australia.
AS1170.4 (2007). “Structural design actions – Earthquake actions in
Australia”, Standards Australia, 45 pp.
AS2159 (1995). “Piling – Design and installation”, Standards
Australia, 56 pp.
ASTM C1018, (1992). “Standard Test for Flexural Toughness and
First-Crack Strength of Fibre-Reinforced Concrete (Using Beam with
Third-Point Loading)”, pp. 514-520.
Beletich, A. (2008). Private communications.
Bjerkeli, I., Tomaszewicz, A. and Jensen, J.J., (1990). “Deformation
Properties and Ductility of Very High Strength Concrete”, Utilization
of High Strength Concrete – Second International Symposium, SP-
121, American Concrete Institute, Detroit, pp. 215-238.
DR05252 (2005). “Concrete Structures”, Draft for Public Comment
Australian Standard, Standards Australia, 200 pp.
Concrete in Australia Vol 35 No 3 45

TECHNICAL PAPER
Foster, S.J. and Attard, M.M., (1997). “Experimental tests on
eccentrically loaded high strength concrete columns”, ACI, Structural
Journal, 94(3): 2295-2303.
Foster S.J. and Attard M.M. (2001). “Strength and Ductility of Fibre
Reinforced High Strength Concrete Columns”, ASCE Journal of
Structural Engineering, Vol. 127, No. 1, January, pp. 28-34.
Ghazi, M., (2001). “Behaviour of eccentrically loaded concrete
columns under confinement”, Phd Thesis, The School of Civil and
Environmental Engineering, The University of New South Wales.
Hognestad, E. (1951). “A Study of Combined Bending and Axial
Load in Reinforced Concrete Members”, Bulletin No. 399, University
of Illinois Engineering Experiment Station, 1951, 128 pp.
Mander J.B., Priestley M.J.N., and Park R., (1988). “Theoretical
stress-strain model for confined concrete”, ASCE, Journal of Structural
Engineering, 114(8), 1804-1825.
Martinez, S., Nilson A.H., and Slate, F.O., (1984). “Spirally
Reinforced High-Strength Concrete Columns”, ACI Journal,
Proceedings Vol. 81, No. 5, pp. 431-442.
Mendis, P., and Kovacic, D.A., (1999). “Lateral reinforcement spacing
for high-strength concrete columns in ordinary moment resisting
frames”, Australian Journal of Structural Engineering, Institution of
Engineers, Australia, Vol. 2, No. 2, pp. 95-104.
Razvi, S.R., and Saatcioglu, M., (1994). “Strength and Deformability
of Confined High-Strength Concrete Columns”, ACI Structural
Journal, Vol. 91, No. 6, pp. 678-687.
Razvi, S.R. and Saatcioglu, M., (1996). Tests of high strength concrete
columns under concentric loading. Dept. Of Civil Eng., University
of Ottawa, Report OCEERC 96-03: 147 pp.
Sheikh, S.A. and Uzumeri, S.M., (1982). “Analytical model for
concrete confinement in tied columns”, J. of Struct. Engrg., ASCE,
108(12), 2703-2722.
Sugano, S., Nagashima, T., Kimura, H., Tamura, A. and Ichikawa, A.,
(1990). “Experimental Studies on Seismic Behaviour of Reinforced
Concrete Members of High Strength Concrete,” Utilization of High
Strength Concrete – Second International Symposium, SP-121,
American Concrete Institute, Detroit, pp. 61-87.
Webb, J. (1993). “High Strength Concrete: Economics, Design and
Ductility”, Concrete International, American Concrete institute, Vol.
15, No. 1, January, pp 27-32.
Zaina, M. (2005). “Strength and ductility of fibre reinforced high
strength concrete columns”, PhD Thesis, , The School of Civil and
Environmental Engineering, The University of New South Wales.
Reinforcement Detailing Handbook
A complete revision of the original first published
in 1975.
The 2007 edition takes into account changes
to relevant standards, design practice and
developments in the choice of available reinforcement
types. Available via the Institute’s
web site or through Standards Australia/SAI
Global.
The basic requirements of good reinforced
concrete detailing are clarity and conciseness.
Unfortunately, there has been a steady deterioration
in the quality and quantity of drawings
supplied for reinforced concrete over the last
twenty years. The net result of poor quality
drawings is increased costs in the material
supply and construction sectors and unacceptable
levels of dispute.
The aim of this manual is to guide designers,
draftsmen and other professionals toward a
uniform method of communicating the design
intention to the construction team so that confusion
cannot arise from the misinterpretation
of the drawings.
46 Concrete in Australia Vol 35 No 3

NATIONAL
NUMBER 53 • AUGUST 2009
PRECASTER
ACN 051 987 181 • ISSN 1037-9908
www.nationalprecast.com.au
Jane Foss Russell Building
University of Sydney
A City within a City
President’s Column
The newly named “Jane Foss Russell Building” is a key component
of Sydney University’s Building for the Future Program. Already
a major University and city landmark, this 12,850 square metre,
seven-storey building provides centralised accommodation for
a wide range of student administrative services together with
commercial and retail spaces. Not only does the development
service the needs of students living on and around the campus but
it also engagingly services the residents of the surrounding areas.
The building was the subject of an international design competition conducted
by Sydney University in 2003. The competition winner, John Wardle Architects,
was formally awarded the commission for the design of the building in
December 2003. The construction contract, the largest infrastructure contract in
the University’s 158 year history, was awarded to Abigroup Contractors.
As John Wardle explains: “The overarching theme of the building is linkage.
Sydney Central is positioned at the intersection of the Darlington and
Camperdown campuses and forms a link between the landscaping currently
underway on both campuses. In addition, it will form a link between the
different student groups at the University and the community with its large and
vibrant plaza area.”
Visually appealing from every angle, the building vision of a ‘city within a city’
for students, staff and visitors features a large outdoor plaza with tiered seating,
function space and cafes, interesting architectural themes and dynamic use of
…story continued on page 2
We welcome the iniative of the Federal Governent with respect to
the school and infrastructure projects that are now commencing and
this will provide a necessary stimulus to the construction industry. It
is important that with this building construction stimulus we do not
overlook the environmental obligations that we all need to target with
this capital expenditure.
By using exposed precast concrete internally in buildings for walls
and floors, the thermal mass benefit of concrete can be maximized.
Concrete has an inherent ability to slowly absorb and release heat and
can also provide a cooling effect for a structure and its occupants.
This allows for constant internal temperatures to be maintained
whilst reducing energy costs and thereby leading to a reduction in
greenhouse gas emissions.
The thermal mass of concrete in buildings:
• Reduces heating energy consumption.
• Smoothes out fluctuations in internal temperatures.
• Delays peak temperatures in offices until the occupants have left.
• Reduces peak temperatures and can make air conditioning
unnecessary.
• Can be used with night time ventilation to eliminate the need for
daytime cooling.
• Can reduce the energy costs of buildings, thereby cutting Carbon
Dioxide emissions.
• When combined with air conditioning results in significant
energy savings.
In this current issue of National Precaster we highlight a number of
projects demonstrating the efficient use of precast concrete to provide
both energy and cost savings.
We trust these project profiles are of interest and invite our readers
to forward information of other projects to further showcase efficient
precast construction.
Peter Healy
President
National Precast... making precast first choice

NATIONAL PRECASTER
NUMBER 53 • AUGUST 2009
… Jane Foss story continued from cover
building materials. External balconies, terraced areas extending between
floors, bleachers and an assortment of sitting areas are incorporated into
the building’s design. These allow all users of the building to enjoy as
much of the natural light and the spectacular views as possible.
Precast concrete manufactured by Hanson Precast features in a multitude
of surprising places, creating an attraction of forms and finishes:
• 82 polished white precast concrete panels made with feldspar
aggregate and imported white cement. Nine of these were curved
– both convex and concave.
• Unusual shaped flat and facetted façade precast panels, following the
soaring façade facets of the building. Some of the precast elements
have up to five polished surfaces at different angles.
• 79 expressive grey precast concrete vaulted external ceiling coffers as
structure to the floors above.
• 25 patterned precast concrete panels cast using Reckli synthetic
rubber form liners. These are displayed externally on two walls. The
concrete for the textured wall panels uses off-white cement.
• The geometry of the buildings provides a vast array of panel shapes
that are seldom seen on other architectural projects – demonstrating
the design versatility of precast.
• A major consideration in the selection of precast concrete was
concern over the possibility of vandalism and grafitti to this 24-hour
open street-front facility. Polished precast is the perfect answer for
such concerns.
• Steps and rooftop elements are in precast.
Jane Foss Russell Building – University of Sydney
Location: City Road, Darlington
Client: The University of Sydney
Project manager: Capital Insight
Architect: John Wardle Architects + GHD + Wilson Architects
Cost consultants: Davis Langdon Australia
Structural engineer: GHD
Façade engineer: Arup Facades
Builder: Abigroup Contractors
Precast manufacturer: Hanson Precast
A major objective was a 5-star green energy rating through
environmentally sustainable design. All buildings constructed
during the Campus 2010 program will be built according to the
University’s ESD Guidelines, utilising new technologies designed
to minimise energy and water usage, and maximising recovery
of waste materials. The building includes the use of low energy
mechanical services. Chilled beams were also used to provide a
passive air conditioning system and solar panels were installed
on the roof.
Precast Concrete Handbook - Edition 2
is to be published this month - Now in Hard Cover!
On sale soon from SAI Global
This much respected publication has been revised and
updated to reflect recent changes to the Building Code of
Australia, relevant Australian Standards and technical data.
Buy the hard cover book OR disk for $187 GST incl*
Buy the hard cover book AND disk for $297 GST incl*
Student edition also available (disk only) for $77 GST incl
* Discounts available for members of National Precast
and the Concrete Institute of Australia.
Register at www.nationalprecast.com.au
to be notified of availability.
PAGE 2
concrete solutions 09
17 – 19 September 2009
Luna Park, Sydney
Don’t miss out on the major
concrete event of the year!
www.concrete09.com.au

NATIONAL PRECASTER NUMBER 53 • AUGUST 2009
Cimitiere House - 5 Star Green Building Stars Precast
Cimitiere House is Tasmania’s first Green
Building design and represents a fantastic
opportunity for Launceston’s business
community. Committed to achieving a 5
Green Star rating design, this building is
situated in the CBD, offers large tenancies
and good parking, and is a wonderful
environment for business owners and
employees to work. The development
provides four levels or around 4600m2 of
office space, with the ground floor housing
a café, retail tenancies and a car park.
Cimitiere House will set the standard for future
commercial premises in Tasmania. An integral
part of achieving this outstanding result is the
inclusion of a precast concrete structure by
project architects Glenn Smith Associates and
project engineers Pitt & Sherry to incorporate
numerous passive and low energy mechanical
systems to produce a green building.
The smart design and fast construction features
of the building permitted savings that can be
allocated to more important areas such as
sustainability and energy saving performance.
Developer, Enmore Enterprises, say that tenants
combining the energy saving potential with
strategic energy management practices can
theoretically save up to 70% on their power bills.
Victorian precast concrete manufacturer Hollow
Core Concrete supplied 4,600 square metres of
hollowcore precast flooring planks to the 5-storey
building. Apart from the ground floor being in
in-situ concrete, all remaining floors were in
hollowcore to eliminate the need for expensive
and time-consuming formwork.
Energy efficient, low cost heating and
cooling
The selection of hollowcore precast flooring
allowed the design team to incorporate an
ingenious energy efficient heating, cooling and
ventilation system that uses the high thermal
mass of hollowcore flooring. The system works
by distributing warmed or cooled fresh air
through the hollow cores at low speeds, allowing
prolonged contact between the air and the slabs.
This enables the concrete to behave as passive
heat exchange elements that release heat to, or
absorb heat from, the air in the slabs. External
temperature variations are not reproduced inside
the building because the maximum heat level
reached during the day is delayed by the thermal
mass of the building until counterbalanced by the
cool of the night.
In the case of Cimitiere House, cool air from the
South side of the building is channelled through
the voids in the hollowcore planks. The cool air is
circulated through the hollowcore and is ducted
into office spaces. During the day, heat generated
within the building is absorbed directly into the
exposed concrete slab. During the cooler months,
solar heated external air ducts on the North side
of the building provide partially warmed air that is
passed over ceiling mounted hydronic radiators
which are fixed to the exposed hollowcore
soffits, providing warm air without drafts, thereby
reducing energy costs.
Precast walls add to thermal mass benefit
The precast flooring in effect becomes an
active component of a sophisticated energy
management system aided by the additional
thermal mass of the precast wall panels. As well
as the precast flooring absorbing the internal
daytime heat, the precast walls provide added
benefit, also absorbing heat during the day. At
absolutely no cost, they release the heat in a
thermal delay cycle during the cooler night,
providing comfortable conditions for the morning
arrival of staff.
A total of 199 precast loadbearing wall panels,
columns and façade panels were supplied to
the project by Tasmanian precast concrete
manufacturer Duggans. Loadbearing wall panels
comprised the West and South elevations, while
the attractive façade panels facing the street
comprised the East and North elevations. Façade
treatment and external finishes to the precast
ranged from off-form, exposed aggregate, to
polished architectural panels. The finishes to the
precast were achieved with exposed structural
aggregate, or polished where high quality
architectural finishes were required.
Wall panels incorporated 20% slag aggregate
from BHP’s Temco plant at Bell Bay Tasmania to
enhance the environmental aspect of recycling
waste material.
Wall panels of size approximately 3200mm x
2800mm ranged in thickness – with 100mm,
150mm and 200mm (with corbel) being typical.
The vertical joint detail incorporated grout keys
at 600mm centres. Loadbearing panel fixing at
floors use cast-in inserts with a topping slab cast
into rebates. The panels were cast in Duggans’
factory on steel tables, and achieved an initial
concrete strength at lifting of 25-32 MPa.
The end result is well summed up by the State
Premier David Bartlett who said at the opening:
“Developments like this one will help to reduce
Tasmania’s greenhouse gas emissions from the
built environment. Buildings which consider
environmentally sustainable design are also
usually healthier homes and healthier workplaces
with increased productivity.”
Cimitiere House Project, Cimitiere Street
Location: Launceston, Tasmania
Project developer: Enmore Enterprises
Architect: Glenn Smith & Associates
Project engineers: Pitt & Sherry (also Green
Star rating accredited professional)
Head contractor: Fairbrother
Precast flooring: Hollow Core Concrete
Precast walling: Duggans
Note - Engineering Solutions Tasmania provided
advice on energy efficiency measures for the
development.
… story continues on page 4

NATIONAL PRECASTER NUMBER 53 • AUGUST 2009
… story continued from page 3
Environmental features that make for
an outstanding building
• Cimitiere House has been designed to be
a healthy building with clean, fresh air,
helping staff stay happy, alert and more
effective at work, increasing productivity
and reducing sick days and staff turnover.
• The development has been registered as a
Five Star Green Star development under the
Green Building Council of Australia’s Green
Star rating tool (Office Design).
• The Green Star assessment process
evaluates building projects or existing
buildings against eight environmental
impact categories (management, indoor
environment quality, energy, transport,
water, building materials, land use and
ecology, emissions). The assessment
process also takes innovation into
consideration.
• The atrium and a series of outdoor spaces
are available to share and mingle with
clients and adjacent businesses.
• The building uses natural light, recycled
water, solar-generated heating and
Tasmanian recyclable building materials.
• There is a low level of power usage and
reduced air emissions, making use of
natural cross-flow ventilation. No airconditioning
is needed.
Glenn Smith, the architect behind Cimitiere
House, found that building green office
space can be more economical than building
conventional office spaces.
“
Although Cimitiere House wasn’t the first
environmentally aware building we have
designed, it is the first opportunity we have
had to design a building specifically aimed
at Green Star registration and to meet all the
criteria. By working with local consultants
and contractors, we were able to meet the
Green Star criteria at a cost equal to or better
than conventional office construction here in
Launceston. At around $1600 a square metre
it proves that it is affordable to build green and
attract a larger number of quality tenants,
Mr Smith said.
”
…Using Precast for Sustainable Construction story continued from page 5
Recycling of concrete waste
The Australian Greenhouse Office encourages
and rewards builders and designers to give
due attention to the use of a significant
recycled content in building construction
or refurbishment. Concrete waste can be
processed to produce roadbase/fill material,
recycled concrete aggregate and recycled
concrete fines. Extensive research has been
undertaken to increase the use of recycled
concrete worldwide. The primary use of
recycled concrete in Australia is for roadbase
material, which not only reduces the need for
natural fill but is also commercially viable.
Use of supplementary cementitious
materials
The quality and properties of concrete can
be improved by replacing a portion of the
cement with industrial by-products known as
supplementary cementitious materials (SCM)
such as fly ash, blast furnace slag and silica
fume. Use of these materials also reduces both
mining of natural resources and greenhouse
emissions associated with cement production
while disposing of a waste material previously
destined for landfill. Fly ash is commonly
used to replace between 20–25% of portland
cement in a blended cement, although
higher percentages are possible and could
be adopted where appropriate for a greater
impact.
Increase the use of recycled water in
concrete
Recycled water has been successfully used in
concrete for many years. Its use, quality and
limits are assessed under AS 1379. In addition,
finishing processes such as polishing and
honing can use recycled water.
Improving building design and
specifications
This involves:
1. Developing low-energy, long-lasting yet
flexible buildings and structures;
2. Exploiting the thermal mass of concrete in
a structure to reduce energy demand;
3. Considering innovative or alternative
design that incorporates de-materialisation
such as using materials that have
undergone an energy-saving process or
action during manufacture or sourcing
such as a filler component in cement
manufacture.
Specific examples of where sustainable
design using precast construction, can
make a considerable environmental
impact can be found in the second
edition of the Precast Concrete
Handbook, on sale soon from SAI
Global – register at
www.nationalprecast.com.au to be
notified of availability.
Precast’s sustainability benefits
come from every angle…
• Lean manufacture, superior
vibration and curing, steel casting
beds, special mixes and recycling
of waste means a higher quality
product with minimal production
waste.
• Moulds are often used repeatedly.
• Local materials are used,
transportation is minimised.
• Recycled materials (eg fly ash, slag,
silica fume, recycled aggregates,
grey water) can be incorporated.
• Precast construction creates less
air pollution, noise and waste (exact
elements are delivered to site).
• Precast can be left exposed,
maximising thermal mass benefits.
• Precast has a long life expectancy
and maintenance and operating
costs are low.
• Precast structures can be retained
and refitted internally.

NATIONAL PRECASTER NUMBER 53 • AUGUST 2009
Using precast
for sustainable
construction
Sustainability is defined as development
that meets the needs of the present
without compromising the ability of
future generations to meet their own
needs. It encourages the protection
of the environment and prudent use
of natural resources. Sustainable
development challenges the design and
construction industry to create buildings
and structures that acknowledge the life
cycle of the structure.
With buildings, recognising that operating a
building over time is far more energy intensive
than developing it, demand for durability and
energy performance is growing. Greenhouse
gas emissions in buildings are due to both
embodied energy and operating energy.
The importance of material choice
Choosing the right materials is a key
consideration in sustainable construction.
When compared with other construction
materials, precast concrete is a responsible
choice for sustainable development. The
underlying properties of precast make a strong
contribution to sustainability. Architects,
engineers and builders are choosing precast
for its durability, reduced maintenance and
energy performance; properties not found
in other construction materials like steel or
timber. Benefits of using precast come from
every angle… efficient manufacture, on site
(during construction) and for the life of the
building.
Design and manufacture
Because AS3600 recognises the high quality
of precast concrete, it rewards the user of
precast concrete with reduced concrete cover to
reinforcement and the physical size of precast
elements can be reduced by up to 15% when
compared with in-situ concrete. In addition,
most precast concrete flooring systems
offer savings of up to 50% in concrete and
reinforcing steel due to the structural efficiency
of their voided or ribbed cross-sections. These
dematerialisation advantages offered by precast
are indeed a benefit to our environment which
can be easily overlooked.
Precast concrete is manufactured in a
controlled environment allowing more efficient
use of materials with very little waste compared
with in-situ concrete.
The advantage of controlled manufacture
becomes apparent as each part of the process
can be easily monitored and controlled due to
the operations being repetitive. Employment
of lean production methods and sophisticated
quality systems in the factory, as well as
superior vibration and curing techniques, steel
casting beds, repeated use of moulds and
specially designed mixes mean a higher quality
product with minimal production waste. The
minimal waste which is generated in the factory
is more readily recycled because production is
in one location.
To reduce the use of virgin materials and
the overall environmental burden, recycled
materials such as fly ash, slag, silica fume,
recycled aggregates and water can be
incorporated into precast concrete. Use of such
products diverts them away from otherwise
being added to the growing landfill mass.
During construction
On site, precast construction creates less air
pollution, noise and debris. Local materials are
often used and transportation is minimised.
Formwork is reduced or eliminated and
buildings can be erected quickly. As well,
site waste is significantly reduced as exact
elements (in both size and quantity) are
delivered to the construction site.
ABOVE LEFT: Off form precast manufactured by
Westkon Precast has been left exposed for minimal
maintenance in the Caroline Springs Library and
Community Centre. Whilst a painted finish was
specified, the architect was so impressed with the
off-form finish that the specification was changed.
ABOVE RIGHT: Precast concrete is manufactured
in a controlled environment allowing more efficient
use of materials with very little waste.
LEFT: ANU’s Hedley Bull Centre - repeated use of
moulds and specially designed mixes mean a higher
quality product with minimal production waste.
Post construction
What happens after construction can also make
a solid contribution to sustainable building
strategies.
Precast’s high quality means that it can be left
exposed in order to maximise the benefits of
its inherent high thermal mass. Because of its
high density, precast has the ability to absorb
and store large quantities of heat. This in itself
may improve heating and cooling efficiency by
as much as 30% compared to other building
alternatives.
Further, the high quality and integrity of precast
means that maintenance and operating costs
are low. For minimal on-going maintenance,
precast can be left exposed (with finishes such
as off-form, sandblasted, water-washed, honed,
polished, coloured with oxides or stained). More
durable than other materials, precast provides
long service for high use applications and can
easily have a life expectancy of 100 years.
When the time does come to reuse or renovate
a precast structure, its durability means that
the main portion of the structure is very often
left in place. This helps the environment by
conserving resources as a result of reduced
waste (which otherwise goes to landfill) and
avoiding the environmental impacts of new
construction.
Increasing the sustainability of precast
Although concrete has a high level of
embodied energy, designers and builders
can adopt the following options to reduce
embodied energy and make it more
sustainable.
…story continued on page 4

NUMBER 53 • AUGUST 2009
NATIONAL PRECAST
CONCRETE ASSOCIATION AUSTRALIA
Profile: An Engineer shares his
thoughts on using precast
Engineer Andre Vreugdenburg at PT
Design in Adelaide shares his thoughts on
using precast concrete walls and floors,
particularly in his own new offices:
Q: How did you get started using precast
A: In the early nineties, we started designing
precast structures, winning three awards in
1994, so we’ve stuck to a winning formula. The
economics and construction speed of precast
mean that designing precast wall panels is now a
daily activity – probably the principal activity in
our office, PT Design.
Q: Why do you like precast and also why did you
choose to use precast for your new offices
A: Precast is a structural system that is
considered during the preliminary engineering
design phase alongside other conventional steel
and in-situ concrete systems.
In our new office building, a real benefit of precast
flooring is the long-spanning ability to eliminate
conventional concrete beams and therefore the
need for formwork during construction. And post
construction, column-free space is a real plus
allowing flexibility for future use… something
which is a major asset in terms of attractive
lettable space. The Ultrafloor was able to clear
span 11 metres and also was able to satisfy the
fire rating requirements. This system provided the
thinnest overall structural solution. The available
space between the beams was used to advantage
for hydraulic pipework to minimise ceiling space.
Q: Can you describe other structural aspects of
your new offices
A: The design of the entire structure was a simple
exercise by PT Design – basically using precast
walls and floors virtually as a ‘kit-of-parts’.
In order to complete a building, conventional
construction methods require an enormous
number of individual components and trades,
all needing handling, placing and scheduling,
and that adds to the complexity. With precast the
process is so simple.
The structure includes one polished entry panel
and 17 grit blasted façade panels using Brighton
Lite cement. 81 off form grey loadbearing panels
of 150mm thickness were manufactured by Hicrete
Precast for the internal structure, Southern and
Eastern elevations. The cast in support angles
allowed the flooring to be placed as soon as the
walls were erected and plumbed. The flooring was
installed in one long day, approximately 10 hours
per floor. In all there were 2,500 square metres
of precast flooring over 4.5 levels. The basic
structure was completed in approx 4 months.
We estimate that cost savings of 10% of the
structure costs were achieved by using precast
walling and flooring. This cost saving does not
include the cost benefits of having tenancies
occupied at least six weeks earlier than in-situ
concrete would have permitted.
Q: What about aesthetics
A: We love the look! On floors with exposed
soffits we used the metal pans in the precast floors
for reflectivity and appearance. We were very
pleased with the finishes we achieved – shiny
metallic handrails, ducts, lighting, etc for a theme
which was already set by the shiny metal pans in
the precast floors. All services were exposed.
Q: Having selected this precast flooring system
for your offices, would you use it again
A: Yes, most definitely! We were a little worried
about acoustics but these were good when the
furniture was installed. Once fitted out there are no
acoustic issues apparent. We were very pleased
with aesthetics, buildability, cost and performance
absolutely. One of the most pleasing outcomes
was the floor vibration performance.
Q: What has been your most interesting/
challenging project using precast concrete
flooring
A: Apart from long span applications, generally
more than 9m, we have used this particular
precast flooring system in tight spaces as a
vertical basement retention system, which we
believe has not been used in that application
elsewhere.
Q: Where do you see the future of precast
engineering heading
A: Over the years, precast has become more
common place in Adelaide, as costs and
construction/buildability issues indicate that
precast has considerable advantages over
conventional systems.
Precast flooring systems are renowned
for their long spanning ability – up to 18
metres in some instances. Refer Table
2.2.1.1 Comparative Spans for Floor
Systems in the second edition of the
Precast Concrete Handbook – available
soon from SAI Global – register at www.
nationalprecast.com.au to be notified of
availability.
CORPORATE MEMBERS
Asurco Contracting ■ [08] 8240 0999
Bianco Precast ■ [08] 8359 0666
Delta Corporation ■ [08] 9296 5000 (WA)
Duggans Concrete ■ [03] 6266 3204
Girotto Precast ■ [03] 9794 5185 (VIC) or [02] 9608 5100 (NSW)
[07] 3265 1999 (QLD)
Hanson Precast ■ [02] 9627 2666
Hicrete Precast ■ [08] 8260 1577
Hollow Core Concrete ■ [03] 9369 4944
Humes Australia ■ 1300 361601
Paragon Precast Industries ■ [08] 9454 9300
Precast Concrete Products ■ [07] 3271 2766
Reinforced Earth ■ [02] 9910 9910
SA Precast ■ [08] 8346 1771
Sasso Precast Concrete ■ [02] 9604 9444
Structural Concrete Industries ■ [02] 9411 7764
The Precasters ■ [03] 6267 9261
Ultrafloor (Aust) ■ [02] 4015 2222 or [03] 9614 1787
Waeger Precast ■ [02] 4932 4900
Westkon Precast Concrete ■ [03] 9312 3688
ASSOCIATE MEMBERS
Actech International ■ [03] 9357 3366
Architectural Polymers ■ [02] 9604 8813
Australian Urethane & Styrene ■ [02] 9678 9833
Award Magazine ■ [03] 9600 4286
Barossa Quarries ■ [08] 8564 2227
Baseline Constructions ■ [02] 9080 2222
BASF Construction Chemicals Australia ■ [02] 8811 4200
Bentley Systems ■ [03] 9699 8699
Blue Circle Southern Cement ■ [02] 9033 4000
Building Products News ■ [02] 9422 2929
Cement Australia ■ [03] 9688 1943
Composite Global Solutions ■ [03] 9824 8211
CSR Topcat Safety Rail ■ [02] 9896 5250
Fuchs Lubricants (Australasia) ■ [03] 9300 6400
Grace Construction Products ■ [07] 3276 3809
Hallweld Bennett ■ [08] 8347 0800
Hilti (Aust) ■ 13 12 92
Nawkaw Australia ■ 1300 629 529
OneSteel Reinforcing ■ [02] 8424 9802
Plasticoat ■ [03] 9391 4011
Reckli Form-Liners & Moulds ■ 0418 17 6044
Reid Construction Systems ■ 1300 780 250
RJB Industries ■ [03] 9794 0802
Sanwa ■ [02] 9362 4088
Sika Aust ■ [02] 9725 1145
Stahl Trading ■ 0417 206 890
Sunstate Cement ■ [07] 3895 1199
Unicon Systems ■ [02] 4646 1066
Xypex Australia ■ [02] 6040 2444
PROFESSIONAL ASSOCIATE MEMBERS
Aurecon Australia ■ [02] 9465 5751
BDO Kendalls ■ [02] 9286 5850
Detail 3g ■ [08] 8942 2922
Moray & Agnew ■ [02] 4911 5400
Robert Bird Group ■ [02] 8246 3200
Strine Design ■ [02] 6282 4877
OVERSEAS MEMBERS
British Precast ■ +44 (0) 116 253 6161
Golik Precast Ltd (Hong Kong) ■ 852-2634 1818
Halfen GmbH ■ [03] 9727 7700
OCV Reinforcements ■ [66 2] 745 6960
Redland Precast Concrete Products ■ 852-2590-0328
The information provided in this publication is of a general nature and
should not be regarded as specific advice. Readers are cautioned to
seek appropriate professional advice pertinent to the specific nature
of their interest.
Published by
National Precast Concrete
Association Australia
6/186 Main Road Blackwood SA 5051
Tel [08] 8178 0255 Fax [08] 8178 0355
Email: info@npcaa.com.au
Executive Officer – Sarah Bachmann
www.nationalprecast.com.au

Concrete Pipe
Association of
Australasia
• The structural strength of the pipeline is delivered to site (i.e the
pipe is the strength)
• Concrete pipe does not rely on the soil surrounding it for it’s
strength like other materials
• Steel reinforced concrete pipe has a proven 100 year design life
in Australasia
robuStneSS
• Concrete pipes are tough and can survive mis-handling during
transportation, on site, during installation and after placement .
• The robust nature of concrete pipes means the joints can withstand
shear action during placement.
ConCrete PiPe –
Why ChooSe
Anything elSe
Strong concrete pipe – able to withstand all loads
In the current economic climate asset owners, asset managers,
engineers and contractors are all facing budgetery challenges.
Balancing cost restraints with appropriate choice of materials
for infrastructure is very difficult but extrenely important. If cost
becomes the major focus, then stakeholders can lose sight of project
life, serviceability expectations, and the overall objective of the
infrastructure.
Taking a risk in the design and installation of infrastructure because
of cost issues is fraught with danger. Any failure is unacceptable
and can affect the health, safety and well being of the community.
More often than not these failures can be avoided by choosing
the right materials to be used under the correct design criteria, and
installed using the appropriate methods. This is vitally important for
underground structures such as drainage pipe.
DurAbility
• Concrete pipes are made using raw materials in accordance to
Australian and New Zealand Standards, ensuring manufacturers
make quality pipes.
• Concrete pipes can be tailored for use if neccessary in aggressive
conditions.
• AS/NZS4058 outlines the specific requirements manufacturers
must meet at achieve durable pipe.
• In accordance with AS/NZS4058 “Precast Concrete Pipes”,
steel reinforced concrete pipes can be designed for 100 years in
accordance with the performance based standard.
Why is this so important A number of recent pipeline failures, locally
and around the world, have occurred due to materials being chosen
for conditions they were not appropriate for, or had not been designed
and/or installed in accordance within their specific guidelines.
Circumstances like flood and fire should not be considered unforseen
as design for infrastructure should be in accordance with the worst
case scenario. Steel reinforced concrete pipe has the ability to meet
the most difficult conditions.
So why choose anything else The objective shold be to manufacture,
design and install a pipeline system that will last 100 years. Reinforced
concrete pipe relieves the risk on ALL stormwater drainage projects
without compromise because of it’s Strength, robuStneSS
and DurAbility.
To avoid these risks designers and specifiers should not lose focus on
the important crietria that a pipeline should exhibit. Structural strength,
robustness and long term durability provide security to the community
that any pipeline is found in. Steel reinforced concrete pipe has been
produced in Australia since the early 1900’s and has proven itself
over and over again that it should be the pipe material of choice to
ensure security. How Let’s take a look at the reasons -
Strength
• The inherent nature of concrete is that it is strong.
• Concrete pipe exhibits compressive strengths up to and greater
than 60 MPa
• Concrete pipe can be designed for any site conditions
Left: Robust concrete pipe – no on site handling problems
Right: Durable concrete pipe – exhumed in excellent condition after 50yrs
Concrete Pipe Association
of Australasia
Locked bag 2011 St Leonards NSW 1590
Ph: +61 2 9903 7780 Fax: +61 2 9437 9478
Email: info@concpipe.asn.au
Web: www.concpipe.asn.au

NEWSLETTER No 3 – 2009
The Building Education Revolution (BER) is a Rudd Government
initiative to provide a $14.7 billion boost to schools over the next
three years. All of Australia’s 9,540 schools will benefit from
major and minor infrastructure projects. These projects are in
design phase with construction of the first school in Minto NSW
recently commenced by Hansen Yuncken. Although this rollout
has limited opportunity for post-tensioning, these projects have
been a timely boost to many of our Consultant and Supplier
Associate Members
Following from our comments last month, significant
infrastructure projects are being rolled out nationally. This work
will bring significant opportunities to all our members in QLD, VIC
and NSW.
At the recent RTA briefing held in June, details were provided on
the following:
• F3 to Branxton Freeway – Hunter Expressway- The project
is 40km of dual carriageway with 56 bridges, and is due to
commence in 2010 with completion in 2013. The contribution
from Infrastructure Australia is $1.451 billion.
• Kempsey Bypass – The project is 14.5km of highway upgrade
with major bridge crossings over Macleay River and floodplain.
Both of these projects will be let as a combination of an Alliance
and Design and Construct contracts.
Our DVD presentation entitled “Stress Safe, Work Safe” is now
complete and is available to the construction industry. The
DVD forms a part of our ongoing training and re-certification of
stressing operatives and we are encouraging all Contractors to
use this DVD as part of their site inductions.
To purchase your copy, please email us at: info@ptia.org.au
Best wishes,
DAVID PASH | President
Concrete in Australia Vol 35 No 3 55

PROJECT REPORT
Catagunya Dam is located in central Tasmania, and is owned
and operated by Hydro Tasmania. This dam, completed in
the early 1960’s, is one of a series of eight hydro-electric
power stations on the Derwent River. The dam has significant
engineering heritage as it was the first prestressed dam
constructed in Australia and only the second in the world.
Catagunya Dam, has a width of 365m and is 48 metres high.
The central spillway is 126m wide and 42 metres high. The
two electricity generating turbines can pass 120,000 litres of
water per second.
The anchors installed when the dam was originally
constructed are believed to be suffering corrosion, and have
reached the end of their service life. As these anchors are
inaccessible and cannot be monitored, Hydro Tasmania has
decided to install new, replacement anchors to remove any
uncertainty about the original anchors’ performance.
Structural Systems, with their extensive experience in
large capacity permanent ground anchors, was engaged
to fabricate, install, grout and stress the 90 new anchors
required.
Each of the new permanent anchors, consists of 91 No.
15.7mm strands individually greased and sheathed over
the free length allowing the strand to extend unrestrained
when stressed. The lowest 11m of the anchor is bare
strand allowing load transfer from the anchor to the rock
when grouted to provide the bond zone. The entire anchor
assembly is protected from corrosion by a corrugated and
smooth sheath system utilizing HDPE. The anchors are up to
78m in length with a mass of some 10 Tonnes each and are
embedded up to 30m into the rock substrate beneath the dam.
The vertical anchors will be installed in both abutments and
some 8.5m below the spillway on the 56 degree slope.
The anchors are fabricated on site in the original quarry area
and transported to the dam on specially designed trolleys.
Installation of the anchors is achieved with the use of a
custom installation frame that elevates and bends the anchor
over a series of rollers into a vertical position to be lowered
into its hole. Lowering of the anchor into the hole is controlled
with a braking winch. The critical grouting process which
follows is completed in three stages using Class G Oilwell
cement to the bond length and GP cement to the free length.
To date, four of the anchors have been installed and stressed
using a 2,200 Tonne hydraulic jack purposely built for the
project. These completed anchors now hold the world record
for permanent ground anchors with the largest minimum
breaking load of 25,389kN (2,589 Tonnes), largest lock off
load of 17,772kN (1,812 Tonnes) and largest test load of
19,415kN (1,980 Tonnes).
All of the new replacement anchors are able to be monitored
and restressed throughout their 100 plus year design life.
Whilst anchoring works on the project are still in their early
stage, the Structural Systems team is confident that the works
will be successfully completed on time and within budget.
56 Concrete in Australia Vol 35 No 3

The development of pre‐stressing and in particular posttensioning
techniques has enabled a spectacular extension of
the physical capabilities now achievable in structures. Long span
bridges and the towering highrises of our cities are typical of
“megastructures” that have benefitted from the applications of
post-tensioning techniques.
With ever improving materials (for example higher tensile lower
relaxation steels, carbon fibres etc) prestressing enables the
effective utilisation of lower cost materials (e.g. concrete) to be
used both in compression and tensile elements. As a result, we
can now design and construct elements that are of a low cost,
high structural effectiveness, water tight, in a durable and fire
resistant material.
Post-tensioning gives two additional enormous benefits
particularly relevant to infrastructure: that is the ability to
profile tendons and to provide a means to secure and extend
full continuity of forces through precast elements. Because
we can design and profile tendons, the prestress is located
exactly where it provides the most structural and or in service
benefits. The resulting structure is more efficiently and effectively
pre‐stressed to maximise performance.
Safety, quality and time are typical drivers in modern
infrastructure construction. Post-tensioning enables the safe
and rapid assembly and connection of structural pre‐cast or
prefabricate elements. Elements can be pre‐made off site, in
controlled factory like conditions, off the critical path. Through
post-tensioning, these elements can be assembled, stressed and
incorporated into the permanent structure. The end result is the
ability to create an almost infinite array of efficient, cost effective,
durable and aesthetically pleasing structures.
As in all pre‐stressing applications, post-tensioning needs to
be designed, detailed, installed, stressed and grouted with the
appropriate materials and systems, by suitably trained and
skilled operatives.
Arup has joined the Post-Tensioning Institute of Australia (PTIA)
as an associate member, demonstrating the firm’s commitment
to working with the Institute to improve standards of design and
construction in the post-tensioning industry. As a member, Arup
will collaborate with the PTIA to offer design services for posttension
projects.
Arup's multidisciplinary design and consultancy team has been
involved in a number of significant projects in Queensland
featuring post-tensioning design, including the Macintosh
Island Pedestrian Bridge on the Gold Coast, the Parrerra Canal
Pedestrian Bridge, and the Kurilpa Bridge in Brisbane – the
world’s first tensegrity pedestrian bridge.
The Kurilpa Bridge will provide a much needed pedestrian and
cycle crossing of the Brisbane River. On the northern side it will
soar over the CBD expressway, linking pedestrians to Roma
Street Parklands and Brisbane’s justice precinct.
The north approach spans utilise post-tensioned concrete
beams. Post-tensioned beams were selected as the optimal
solution which allowed the depth of deck below the walkway to
be minimised. Being precast and post-tensioned off site, they
also had the advantage of minimising on site erection time,
reducing the duration and number of night closures required. The
post-tensioned beams used coloured concrete and a custom
section was developed to meet the highly architectural design
requirements.
Arup is a professional services firm providing engineering, design,
planning, project management and consulting services across all
aspects of the built environment. Globally, they are 10,000 strong,
operating out of 92 offices in more than 37 countries.
Concrete in Australia Vol 35 No 3 57

PTIA sponsored Prestressed Concrete Design workshops are presented
by Cement and Concrete Services (CCS). For consulting engineering
firms who are Associate Members of the PTIA, there are significant
subsidies on the fees for these workshops – details are available from
CCS at www.cementandconcrete.com. Registrations for workshops are
to be made through CCS.
These two day workshops are developed for engineers who are familiar
with reinforced concrete but who have little experience with prestressed
concrete and who wish to gain an understanding of the principles of
analysing and designing statically determinate prestressed beams. An
optional third day workshop on computer aided design for prestressed
concrete is also available.
Haggie Reid Pty Ltd
PTIA will not be conducting a seminar series with Concrete Institute in
2009 but hopes to have a number of papers accepted for presentation at
in Sydney from 17-19 September.
Some PTIA seminars may be held in regional locations and details will be
announced in future newsletters and on the PTIA website.
PTIA offers Corporate Member companies a comprehensive Skills
Training course which is presented by a dedicated and fully accredited
training manager. The courses are offered in all states of Australia,
subject to sufficient numbers. The course offers five modules, with
modules 1 & 2 (General Safety & Installation) as a one day course, and
modules 3 & 4 (Stressing & Grouting) as a second day, advanced course.
A new module 5 (Multi-strand) has now been added to the training
program.
On successful completion, course attendees are provided with a
Skill Training Course card which is current for 12 months. Annual
reassessment is required after that.
• Arup
For details about course dates and locations, or to book a course for your
workforce, contact the PTIA Training Manager, Brad Parkinson on 03 9296
8100 or mobile 0437 439 573, or by email to bradp@structural.com.au.
• Khin Tandar Soe (ADFA, UNSW)
• Kerstan Nolan (QUT)
Please visit the PTIA web site
for details about
membership, membership benefits
and membership application
forms. If you have questions about
membership, please contact PTIA
through this web site and our office
will contact you to discuss your
questions.
58 Concrete in Australia Vol 35 No 3

One Steel’s Whyalla steelworks. Concrete remediation work was recently carried out in the plant’s salt water pumphouse.
Salt water pump-house concrete remediation
Remediation works were recently required to be performed
in the salt water pump house within the OneSteel Whyalla
steelworks site.
The problems arose from salt water ingress through the walls.
The remedial works included:
• breakout of structurally unsound concrete
• removal and replacement of unserviceable steel
reinforcement
• concrete reinstatement.
SikaTop –110 EpoCem was selected for use as a bonding
agent and anti-corrosion coating due to the product quality
and ease of application. The product was applied by brush as
working the product into the surface promotes adhesion.
Spray application of SikaCrete Gunite-103 using an Aliva
PHOTO: BOB JACKSON
gunite pump was the chosen method of concrete reinstatement
by DSE Civil. A spray applied product was decided on due to
its increased speed of application. The very confined conditions,
due to the presence of scaffolding and a staircase, made spraying
a challenging exercise. However, it proved to be very effective in
providing a quality final repair outcome. The final surface was
smoothed out with a trowel.
Information for this article was provided by Sika Australia, a
member of the Australian Concrete Repair Association (ACRA).
Sika is proud of its quality products and service to the concrete
repair industry.
ACRA is keen to attract new members who operate in the
field of concrete repair as a core activity, and can demonstrate
the required expertise and commitment to quality.
Concrete in Australia Vol 35 No 3 59

PROJECT REVIEW
The Very Cosmopolitan Metropolitan
Overlooking Lake Burley Griffin, spanning an
entire city block and with easy access to nearby city
offices, the cosmopolitan 343-unit Metropolitan
Apartment complex in Civic Square is quickly
becoming the residence of choice for busy people
wanting a convenient, yet relaxing lifestyle in the
nation’s capital.
The Metropolitan offers a luxurious, low maintenance,
leisurely environment in a green urban setting with
tree-lined boulevards, landscaped gardens and attractive
pedestrian walkways. Worth more than $80 million, this
multi-level building has much to offer potential residents and
is already developing its own community spirit.
Both single and two-storey apartments are available, many
with double frontages. All have at least one balcony providing
sweeping views of either the lake, the surrounding mountains
or a private landscaped space, while the interiors have been
tastefully designed and have ensuite, intercom, air-conditioning
and spacious, light-filled kitchens and bathrooms.
Construction Manager David Colbertaldo of Hindmarsh says,
“Each of the buildings has its own unique character and we
wanted different aesthetics for each. To achieve this we used
a range of colours and textures from the Boral masonry range
which suited our needs perfectly and were very cost-effective.”
The project required almost 150,000 masonry blocks in both
Split Face and Smooth Face in a range of colours including
Charcoal, Sandune, Alabaster, Midway, Wilderness and Pearl
Grey. The complex supply schedule was undertaken over 18
months and was completed in four stages to fit in with the
timetable of constructing the eight individual buildings.
“We tried to ensure that all operations ranging from design to
construction were carried out in an efficient and cost-effective
manner and we have produced a residential development that is
truly outstanding in every sense of the word,” says David.
Architect/Designer: Bligh Voller Nield
Builder: Hindmarsh
Developer: Amalgamated Property Group
Product: Boral Masonry – Designer Block
60 Concrete in Australia Vol 35 No 3

Concrete Masonry Association of Australia Limited
The Concrete Masonry Association of Australia
publishes technical manuals and bulletins,
maintains a web site, conducts conferences and
courses and provides a technical advisory service
which is available to the construction industry and
other users of concrete masonry products.
CMAA publications are generally available free
online as PDF documents, some are also for sale in
printed form or on CD. Publications and software
are found in the Technical Information section
of the CMAA website. The following walling
documents are available in this area:
MA45 Concrete Masonry Handbook
MA46 Manufacture of Concrete Masonry
MA54 Single-Leaf Masonry – Design Manual
MA55 Design and Construction of Concrete
Masonry Buildings (on CD-ROM)
DS1 National Metric Coding System
DS3 Concrete Masonry Lintels
DS4 Compressive Load Capacity of
Concrete Masonry
DS5 Concrete Masonry Fences
MA45
There is also an extensive range of manuals, data sheets and technical papers
covering concrete segmental paving and retaining walls. The paving software
package, LOCKPAVE-PERMPAVE ® is available for the structural design of
interlocking concrete segmental pavements and permeable pavements.
MA55
Concrete Flag Pavements
Design and Construction Guide
Concrete MasonryWalling
Manufacture of Concrete Masonry
Concrete Masonry Association of Australia
Concrete MasonryWalling
Single-Leaf Masonry
Design Manual
1
MA46
MA54

Member driven solutions to today’s reinforced concrete needs
The Steel Reinforcement Institute of Australia
(SRIA) is a national non-profit organisation
providing a high quality technical support and
information service to the Australian building
industry. SRIA is funded and supported by the
manufacturers and processor suppliers of steel
reinforcing and associated hardware products
used in Australian construction.
Our corporate vision is to develop a respected
and influential organisation to ensure that
reinforced concrete remains the preeminent
building material in Australia.
Membership
The membership of the SRIA consists of
corporate and associate members.
Corporate members are required to be
either members of the Australian Certification
Authority for Reinforcing Steels (ACRS), or obtain
ISO 9000 certification plus multiple product
approvals set by the SRIA Board.
The corporate membership is composed of
Australian steel producers, and steel processors
who may process either Australian or imported
material.
The Australian steel producers are OneSteel
Market Mills and TASCO – The Australian Steel
Company Operations.
As producers they are responsible for producing
reinforcing steel in bar (straight length) or coil
form from a hot rolling process.
They produce bar in nominal diameters ranging
from 10mm to 40mm diameter, and up to
50mm on request.
The coil is typically produced in 12mm and
16mm diameters.
The steel processors are responsible for the
subsequent processing of reinforcing steel,
locally produced or imported, which is supplied
by a steel producer. They may be importers
of both bar and coil, use Australian produced
materials, or a combination of both.
The processor members are Active Steel, AKZ
Reinforcing, ARC – The Australian Reinforcing
Co., Ausreo, Best Bar, Bianco Reinforcing, Mesh &
Bar, NatSteel Australia, Neumann Steel, OneSteel
Reinforcing, Vicmesh and Wire Industries.
Processors are able to change the shape of bar
supplied by the mills, to the specifications of the
design engineer.
The processing may include cold-rolling,
cold-drawing, decoiling and straightening, or
automatic, electrical-resistance welding to
form mesh.
The Processors are also able to bend mesh when
required, and they may also cold process the coil
supplied by the mills.
All steel reinforcement materials must be
supplied to meet the minimum requirements
specified in AS/NZS 4671- 2001.
Associate members consist of companies
that manufacture and/or distribute and market
products used with steel reinforced concrete
construction.
Our current associate members are Action
Products, Ancon – Division of Tyco Building
Products, aSa – Applied Systems Associates,
Connolly Key Joint, Danley Construction
Products, Erico Products Australia, Modfix Div of
ITW Construction Products, Monkey Steel and
Reid Coctruction Systems.
These companies bring a wealth of specialist
knowledge to the support we offer to design
engineers, builders and contractors.
Their extensive range of products and services
cover expert knowledge in the use of:
ß Couplers (threaded, bolted, taper threaded,
anchors that replace the need for cogged or
hooked bar ends)
ß bar chairs
ß products (and the methods) to maintain
continuity of reinforcement at construction
joints in concrete
ß shear connectors, (for slabs, punching shear
etc)
ß formwork tie systems and splice units.
Some design software packages as well pdf
instruction sheets to use with some of the
products listed are offered on their respective
websites.
Full contact details for all SRIA Corporate and
Associate Members are listed on the SRIA
website, www.sria.com.au, together with direct
web links to their websites.
The SRIA website enables the user to quickly
access data on products produced and supplied
by our corporate and associate members.
www.sria.com.au

LIBRARY
LATEST TITLES
Concrete Institute members are welcome to use the Cement Concrete and Aggregates Australia’s library services. The library
is located at the CCAA’s Sydney office on Level 6, 504 Pacific Highway, St Leonards, NSW. The databases can be accessed
electronically via www.concrete.net.au. The postal address is Locked Bag 2010, St Leonards, NSW 1590. Phone (02) 9903
7721, fax (02) 9437 9473, email: info@ccaa.com.au
BRIDGES; STRUCTURAL DESIGN; STANDARDS
Designers’ guide to EN 1992-2
Hendy C R, Smith D A
Accession number: 08A04223
Eurocode 2 : design of concrete structures Part 2 :
Concrete bridges, 2007
The principal aim of this book is to provide the user with
guidance on the interpretation and use of EN 1992-2 and
to present worked examples. It covers topics that will be
encountered in typical concrete bridge designs and explains the
relationship between EN 1992-2 and the other Eurocodes.
CONCRETE PROPERTIES; STANDARDS; CONCRETE
TESTING; SWITZERLAND
Information-based formulation for Bayesian updating
of the Eurocode 2 creep model
Raphael W, Faddoul R et al
Journal of the fib Vol 10, no 2 pp 55 – 62, June 2009
Accession number: 20090655
The disparity between theoretical and experimental results
reveals that the creep of concrete is often underestimated by
most, if not all, codes of design. This is particularly true in
the case of Eurocode 2. Thus it is necessary to calibrate the
present code models. Bayesian-type inferences turn out to be
an especially suitable tool for the work needed in revising and
updating design codes. This is by virtue of their capability in
incorporating additional information resulting from current
practice and research aimed at improving existing models. In
this paper corrective coefficients are proposed for the Eurocode
model, allowing better estimation of the long-term creep
of concrete. To achieve this aim the authors rely on a large
database of experimental results, compiled by collecting data
from several research institutions in Europe. Two descriptive
statistical methods are applied in order to compare the
experimental results from the above-mentioned database with
results calculated using the Eurocode 2 model for the same
input parameters.
ROADS; AGGREGATES
The equivalent heavy vehicle concept in Australian
sprayed seal design
Neaylon K, Spies K, Spies R, Alderson A
Accession number: 08A04228
Proceedings of sprayed sealing conference 2008
The foremost challenge facing Australian spray seal designers is
the performance of sprayed seals under the increasing numbers
of large heavy vehicles on major transportation routes
connecting capital cities and in rural areas of NSW, Queensland
and WA. It is expected that the Australian freight task will
increase by 25% between 2000 and 2010, with most of this
increase already occurring. Based on data collected in rural
areas, the traffic adjustment for heavy vehicles was amended in
the 2006 update of the Austroads sprayed seal design method.
This paper discusses the investigation currently being conducted
into the effect of these large heavy vehicles on sprayed seals,
and the concept and development of Equivalent Heavy Vehicles
introduced in the Australian design method in 2006. This paper
describes the next steps in rationalising this concept.
CONCRETE STRENGTH; COLUMNS; TESTING
Unified strength model for square and circular concrete
columns confined by external jacket
Wu Y F, Wang L M
Accession number: 200903253
ASCE Journal of Structural Engineering, Vol 135, no 3, pp
253-261, March 2009
It is logical that a confined concrete strength model for columns
with a corner radius should degenerate into a model for circular
and sharp cornered square columns. However, this is not the
case in any of the existing models, except for an early one by
Mirmiran et al in 1998. Extensive experimental testing on
fiber-reinforced polymer (FRP)-confined concrete columns that
have a continuous variation of from 0 to 1 has been undertaken
by the writers. Based on the experimental findings, a rational
procedure is proposed for developing a unified strength model
for FRP-confined concrete columns with an arbitrary corner
radius. A comprehensive database has been established by
collecting all of the available experimental results from the open
literature for evaluation of the unified model. The proposed
procedure is applicable to concrete columns confined not only
by FRP materials but also other materials such as steel plates.
ARCHITECTURE; CONCRETE CONSTRUCTION
Concrete architecture around the globe
Glaesle J, April 2009
Accession number: 20090485
Hardly any other building material is in such demand at the
moment by architects and is more diverse in use than concrete.
Concrete technical innovations and developments pave the
way for a new exciting future. Self-compacting and ultrahigh
performance concretes promise sculptural and filigree
constructions and an architecture that could not be built in
the past. Glass-fibre and textile-reinforced or even translucent
concrete open up the range of possibilities that concrete
architecture offers the planners today.
US CEMENT INDUSTRY
2009 IEEE cement industry technical conference
Accession number: 08A04234
The Institute of Electrical and Electronic Engineers Inc
The most current technical information, the latest technical
developments and the most vital issues in the Portland cement
industry today.
Concrete in Australia Vol 35 No 3 63

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64 Concrete in Australia Vol 35 No 3

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Concrete in Australia Vol 35 No 3 65

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