alhosn university journal of engineering & applied sciences

ALHOSN UNIVERSITY JOURNALOF ENGINEERING AND APPLIED SCIENCESADVISORY BOARD(in alphabetical order)Prof. Ghassan AouadSalford University, UKProf. Goodarz AhmadiClarkson University, USAProf. Hisham ElkadiUniversity of Ulster, UKProf. Jamal A. AbdallaAmerican University of Sharjah, UAEDr. Khaled El-SawyUnited Arab Emirates University, UAEDr. Mohamed LachemiRyerson University, CanadaProf. Mufid Abdul Wahab SamaraiSharjah University, UAEProf. Nizar Al-HolouUniversity of Detroit Mercy, USAProf. Riadh Al-MahaidiMonash University, AustrialiaProf. Sadik DostUniversity of Victoria, CanadaProf. Ziad SaghirRyerson University, Canada2

DIGITAL DIVIDE : A PROBLEM OF ACCESS OR USE OF ICT: THE CASE OF ACADEMIC INSTITUTIONS IN TUNISIAKomis [5] and Makrakis [9] based their studies on an analysis of school practices of variousdeveloped countries and proposals made by committees of experts and arrived at three modelswhich were related to the introduction and integration of ICT into education systems. The firstmodel considers ICT as a teaching subject. It suggests imparting computer knowledge byconsidering IT as a separate discipline and promoting a process computer. The second model isthe antithesis of the first and considers IT as a tool for teaching and learning in all disciplinesand a means to an interdisciplinary approach and integral learning processes. The third modelwhich encompasses the others is a result of the inability of a short-term application of theintegrated approach, and the need to have a certain level of literacy, at least currently,concerning the use of the computer.More recently, Lebrun [7] specified three different applications of ICT in education, whichwere the reactive, proactive and interactive mode respectively. The reactive mode regards ICTas resources for learning and therefore the emphasis is on information extracted from theenvironment (culture, knowledge etc) that has teachers or sources of knowledge such as media,database, encyclopedias, etc. to impart this information. The related teaching methods here arecourses, presentations, lectures and exercise sessions.. The proactive mode specifies theobjective from the use of ICT as manipulating the world and its representations. The emphasisis on the cognitive skills (analysis, synthesis, evaluation, critical thinking) that the learner willhave to deploy into the environment. It is for the learner to reconstruct, to rediscover throughthe use of simulations (analysis) and modeling (synthesis) to solve problems and createprojects.The main tools employed are programming software, simulation and modeling software,compact disks and websites. The teaching methods which are related to this mode adoptproblem solving approaches, project development, the real and virtual laboratories, etc. TheInteractive mode aims to use ICT for mutual knowledge sharing. In this mode, the focus ismore on interpersonal skills. This can be seen as the conjunction of the two previous modeswith different versions of relational interactivity: 1) Immersion in an environment (roleplaying, interaction with virtual partners) 2) Interaction between distant partners (mail, news,listings and educational uses) 3) Interaction with local partners.The digital pedagogy could be defined as the set of techniques, media and digital meanscurrently being used to optimize the teaching-learning process. This pedagogy as articulated byBloom [2] predicted that with sufficient time and resources, all students should be able toachieve all the objectives of a course. However, the percentage of failures might be relativelyhigh. All the difficulties mentioned above largely explain why a large proportion of faculty isstill very reluctant to integrate ICT in their daily teaching activities, and confined in far moretraditional approaches. This is mainly due to lack of supervisors support, professional andtechnical support for the creation of teaching materials adapted to this new paradigm. The gapalso widens due to the lack of studies based on Tunisia.39

HUSAM-ALDIN N. AL MALKAWI, ABIR BEN HAJ HAMIDA, REKHA PILLAI3. METHODOLOGYThe paper employed qualitative research design and descriptive statistics for the purpose ofcompleting the study. A questionnaire was developed after having been inspired by theresearch done within the research group on the interdisciplinary in teaching education at theUniversity of Shebrooke, Canada [6]. A pilot study was conducted by testing the questionnaireon a small number of instructors before conducting the main survey for testing errors instructure design and omissions, existence of ambiguity etc. It also helps to understand theextent of understandability of questions framed. Adequate Response categories were developedfor questions in order to facilitate the process of coding and analysis.This questionnaire was divided into four main parts. The first part was related to thedescription of the equipment in the institution and to the respondents' perception of thesefacilities. The second part addressed the ICT access in education. The third part dealt with thepractical use of these tools, both personal and on the teaching practices. The fourth partincluded 7 items with a response forming an agreement scale in relation to ICT 1 .The questionnaire was administered personally or by mail to the target sample of 100instructors from a population of 530 instructors in the year 2007. The instructors belonged toSFAX University, Tunisia. The University encompasses 4 colleges, each specializing indifferent disciplines namely Natural Science, Social Science, Computer Science and Business.The sample was chosen by quota sampling following Charfi [3] in her study about the attitudesof teachers and researchers towards internet.The data were processed according to the nature of the variables that determine them. Initially,we calculated the structures of frequencies and percentages for all items available for anoverview of the study sample and to find out more of its characteristics.Discriminant analysis was later used to determine which continuous variables discriminatebetween two or more naturally occurring groups. There are several tests of significance, but weonly present Wilks' lambda here. Wilks' lambda is used as a test of mean differences inDiscriminant Analysis, such that the smaller the lambda for an independent variable, the morethat variable contributes to the discriminant function. Lambda varies from 0 to 1. The F-test ofWilks' lambda shows which variables contributions are significant. The aim was to study therelationship between a qualitative variable and a set of quantitative variables and to find outthe most discriminating variables in order to investigate if they are related to the access or theuse of ICT.1 The questionnaire is available upon request.410

HUSAM-ALDIN N. AL MALKAWI, ABIR BEN HAJ HAMIDA, REKHA PILLAITable 7: Results Summary ofResponses from Teachers (Usageof ICT)I like to use the computer to prepare coursematerials.I found that using the Internet facilitates therealization of my lesson plans.When I am in class, the computer is part ofmy routine teaching tool.The computer is essentially a means ofcommunication (electronic mail).The computer is essentially a means ofdistractionThe computer is essentially an instrument ofwork outside the classroom context(information retrieval, preparation ofcourse).The use of ICT in education is justified ininstitutions in science or technology and notin other institutions.Stronglydisagree(%)Disagree(%)Agree(%)StronglyAgree(%)6.2 25.9 43.2 24.79.9 34.6 30.9 24.722.2 51.9 19.8 6.23.7 23.5 59.3 13.612.3 66.7 19.8 1.23.7 24.7 51.9 19.861.7 35.8 0 2.5The survey on the attitude to ICT in education attained positive responses.According to survey results, we note that 67.9% of teachers surveyed agreed on thepreparation of materials for teaching using the computer. However, only 55.6% said thatsurfing the Internet facilitated the preparation of the course. In addition 74.1% of teacherssurveyed said that IT did not occupy a part of their everyday teaching tool. The computer wasessentially a communication medium for 72.9% of subjects and did not pose as a means ofdistraction for 79% of teachers. It also served as an instrument of work outside the class for71.7% of respondents.Finally, almost all respondents admitted that the use of ICT cannot be justified only in sciencebasedinstitutions. These results arrived at the fact that ICT was only utilised for sendingemails which in turn reaffirmed its stand as a communication tool.The Wilks’ lambda test proved that the effect of gender, age, rank and experience of theteachers, were not related to the usage of ICT. The discriminating variables were "number ofInternet connections per week", "number of email use by week," "learning mode", "the use ofcommunications software" and "the use of common software". Thus we can conclude that thedifferences among instructors arise due to the differences in the method of using ICT.5. CONCLUSIONS AND RECOMMENDATIONSThe purpose of this research was to explain the causes of digital divide in the academicinstitutions in developing countries using Tunisia as a case study. Our main objective was toclarify if it is due to a problem of access or use of ICT. A survey was conducted among asample of 100 instructors from the Sfax University with a response rate of 81 percent.1016

DIGITAL DIVIDE : A PROBLEM OF ACCESS OR USE OF ICT: THE CASE OF ACADEMIC INSTITUTIONS IN TUNISIAIt follows from this survey that the majority of instructors have developed a minimum level ofskills to use computers. Regardless of academic rank, they meet the criteria defining thefunctional computer literacy, so they are able to use common office software (Word, Excel andPowerPoint) and to use the Internet (surfing and communicating). Moreover, the majority ofthese instructors were self trained or trained by colleagues and few received professionaltraining. Therefore, we can conclude that providing adequate training programs can upgradethe level of integration of ICT in education.The study showed that most respondents had a computer, both at home and at work and weremainly users of office software. They generally used multimedia technology (e-mail orInternet) for private purpose and for widening access to sources of information for theirrespective course.Regardless of the gender, age, rank and experience of the teachers, we found significantdifferences in relation with the use of ICT in teaching. The discriminating variables were"number of Internet connections per week", "number of email use by week," "learning mode","the use of communications software" and "the use of common software". Thus, we canconclude that the differences among instructors arise due to the differences in ICT usage.The Tunisian government provided sufficient infrastructure and an environment conducive forthe integration of ICT in education. However there is a strong trend towards the establishmentof E-education. Consequently, it is a question of willingness from the instructors tosuccessfully integrate these new technologies in the education process. The effectiveness ofthese technologies depended primarily on ability and willingness of stakeholders in theacademic field. In this sense, the emphasis here is on human capital. So we can conclude thatthese problems are with the use of ICT rather than access.Finally, we argue that emphasis should be provided on training the faculty for updating themwith the latest technology used in institutions. A strategic alliance with technological expertscan prove beneficial for the institutions as they can benefit from the expertise provided by thecompanies who are adept in latest technological developments. A new curriculumencompassing the imperativeness of the application of ICT in routine teaching can be framed.Policies can be implemented which necessitates the adoption of ICT by institutions in order toattain ministry recognition.Limitations arise in this study due to the limited time period and sample used in this research.Therefore suggestions for future research centres around the adoption of a longer time periodand larger sample.This paper which used Tunisia as a case study can be replicated in the educational environmentof other developing countries in order to examine the existence of digital gap and the majorfactors contributing to this gap in these countries and to see whether they face similar issuesconcerning ICT.1117

HUSAM-ALDIN N. AL MALKAWI, ABIR BEN HAJ HAMIDA, REKHA PILLAI6. REFERENCES[1] Baile, S. and Lefievre, V. (2003). "The successful use of email - a study of itsdeterminants within a production unit of aircraft maker", 8th conference of AIM, Grenoble.[2] Bloom, B S. (1968). Learning for mastery, Evaluation Comment. (UCLA-CSIEP), 1(2), 1-12.[3] Charfi, A. (2004). "Attitudes of teachers’ vis-à-vis ICT", Working Paper, FSEG Sfax-TUNISIA.[4] Gurova, E. (2001). "The Digital Divide - A Research perspective.” Seville, IPTS.[5] Komis, V. (2001). "The information technology and communications in the Greekeducational system: the difficult path of integration," Journal of Education and PublicInformation, No. 101.[6] Larose, F. (1999). "The information technology and communication in university teachingand training teachers: Myths and Realities," Journal of Science Education:Perspectives of Future Education, Volume 27, No. 1[7] Lebrun, M. (2002). "Theories and methods for teaching and learning: Which place for ICTin Education", De Boeck, Bruxelles-Paris.[8] Looker, D. & Thiessen, V. (2003). "The digital divide in Canadian schools: factors thataffect access to information technologies and their use by students", Working Paper, No.81-597 -XIE.[9] Makrakis, V. (1988). Computers in Education, Studies in International and ComparativeEducation, Stockholm International Education.[10] Reddick, A., Boucher and C., Groseilliers, M. (2000). "The Dual Digital Divide: TheInformation Highway in Canada", Public Interest Advocacy Center, Ottawa.[11] Renaud, P and Torres, A. (1996). "lnternet, a chance for the South", Diplomatic World,p 6.1218

AHU J. of Engineering & Applied Sciences 3 (2) : 19-26 (2011)© 2010 ALHOSN UniversityA COMPARISON OF GENERAL DESIGN AND LOADREQUIREMENTS IN BUILDING CODES INCANADA AND SYRIASamer Al-Martini *College of Engineering and Computer Science,Department of Civil Engineering, Abu Dhabi University, Abu Dhabi, UAEABSTRACT: This paper aims at comparing the Syrian and Canadian codes used for design and execution ofreinforced concrete building structures. Primarily, the Arabic Syrian Code for Design and Execution ofReinforced Building Structures, 2004 (ASC, 04) has been studied and compared with both the National BuildingCode of Canada (NBCC) for loads specification and the Canadian Standard Association Code (CSA A23.3) forreinforced concrete specification. The study revealed that the Syrian code has increased the “factor of safety” byrecommending higher values of load factors where, the factored dead load and the live load are almost 20% less inCanadian code than that in Syrian code due the difference in the dead and the live loads magnification factors.KEYWORDS: building codes, load factors, factored resistance, live load demand, nominal resistance1. INTRODUCTIONThe Arabic Syrian Code for Design and Execution of Reinforced Building Structures (ASC)[1] is adopted in Syria for designing a building. In Canada, the National Building Code ofCanada (NBCC A23.3-04) [2] for loads specification and the Canadian Standard AssociationCode (CSA A23.3) [3] for reinforced concrete specification are used for designing buildings.The Syrian and Canadian codes share the basic rationale, and have many common features.They contain general requirements for safety, serviceability, and structural integrity.It may be worth presenting a brief historical review of both codes and how they weredeveloped and modified over years. The constitution in Canada gives each province theresponsibility for setting its own building construction regulation. In a few cases the provinceshave given the municipalities the historic right of writing their own building codes. As such, inthe early years, regulating building construction in Canada was done by patch working ofbuilding codes across Canada.The National Building Code in Canada was first published in 1941 by the federal government.This code was later adopted by the various provinces and municipalities in Canada during thenext 20 years. Since 1960, The National Building Code of Canada has been revised aboutevery five years up to 1995. However, the 2000 edition of the building code was takenconsiderably longer time than what was expected and the next edition of the National BuildingCode of Canada was published in 2005. The available 2005 edition of the National BuildingCode of Canada (NBC) has over 800 technical changes. The 2010 National Building of CanadaCodes was published on November 29, 2010._____________________________* Corresponding Author.E-mail : samer.almartini@adu.ac.ae119

SAMER AL-MARTINIThe Syrian code has been modified over time as well. The second edition of the Syrian codewas issued in 1995 and then was followed up with three appendices in 1996, 1997, and 2000;these appendices provided specifications for building design against earthquake. The secondedition along with its appendices has provided the Syrian civil engineers with the necessaryaids required for designing anti-seismic structures. However, during implementing the secondedition of the code, it was realized that the code needs to be modified in order to account forthe rapid advancement in computer technology and the continuous development of structuralsoftware. Moreover, it has become necessary that the code covers steel structures as well.Therefore, the third edition of the code was published in 2004 along with 14 appendices toaccount for the abovementioned aspects.2. COMPARISON BETWEEN THE SYRIAN AND CANADIAN CODES2.1 Structural Load SpecificationsDead LoadsThis term includes the weight of the member itself, and the weight of all members permanentlysupported on this member such as partitions and appliances. Partition loads used in the designshall be shown on the drawings. The calculation of the dead load in both codes follow similarconcepts taking into consideration the type of material used in each case with its unit weight.The basic difference between the two codes is in the magnification factor used for the deadloads. In the ACS the dead load is multiplied by a factor of 1.5 while it is multiplied by 1.25 inthe NBCC.Live LoadsThe live loads on an area of floor or roof depend on the intended use of the particular structure.Table 1 shows a comparison between the uniformly distributed load patterns taken from Table5.2 and Table 4.1.5.3 in Syrian and Canadian Codes [1,2], respectively.Table 1- Live loads specification in ASC and NBCC codesCodes bedrooms (KPa) Stairs (KPa) Roofs (KPa) LL Reduction FactorsASC 2 3 1 1.8NBCC 1.9 1.9 1 1.5220

A COMPARISON OF GENERAL DESIGN AND LOAD REQUIREMENTS IN BUILDING CODES IN CANADA AND SYRIASnow LoadsIn the ASC the snow load is taken considering the elevation from the sea level [1]. The ASCwould require that snow load on a roof of an ordinary building in Damascus region to be takenas 1 KPa [1]. In NBCC the snow load on a roof is determined considering the product of aground snow load (determined from a map) over 30 years and a ground to-roof conversionfactor [2]. The NBBC would require that the roof of an ordinary building to be designed for asnow load of 2 KPa. The difference between the two values is a logical reflection of thedifference in weather conditions between the two regions.Wind LoadsIn the ASC the pressure exerted by the wind on an ordinary building with low height⎛ height ⎞⎜ < 4⎟is taken only as a static horizontal uniformly distributed load according to the⎝ width ⎠following equation:P = CpCeksq(KPa) (1)Where,C p is the sum of the pressure coefficients related to the surface roughness and number and itsvalues is taken from Table 5.5 from the ASC [1].C e is a coefficient related to building height from the ground surface. This factor accounts forthe increase in the wind velocity with height. It is calculated according to the following42equation: C e= 1 −(2)h + 60k s is a coefficient related to the location of the building in terms of its exposure to wind and itis taken from Table 5.6 in the code.q is the reference velocity pressure in KPa, and it is defined as the pressure due to windexcreted on a flat plate suspended at 10 m above the ground surface. It is calculated accordingto the following equation:2q = V /1630(3)Where, V is average wind velocity (m/s)In the NBCC the wind load is calculated according to the following equation:p = qCeCgCp(4)Where,q is calculated according to the following equation:2q = 0.5ρV(5)Where, ρ is the air density during the windy period of the year and its values are tabulated inAppendix C 2-12 of NBBC [2], V is hourly average wind velocity.321

SAMER AL-MARTINIC e is the exposure facto and it is. It is calculated according to the following equation:0.2⎛ hi10 ⎟ ⎞Ce= ⎜(6)⎝ ⎠C g is the gust factor; it accounts that when gusts blow they may have velocity greater than thatof wind. In the simplified method, this term is taken as 2 for the design of building as whole. Itshould be noted that this term is not considered in the ASC for the calculation of loads due towind.C p is the external pressure coefficient. This factor is given in Commentary B 2-17 of the NBCCfor various shaped building [2].Load and General Design Requirements for Canadian and Syrian CodesThe load requirements in both codes are similar in their rationale but different in their specifics.The load combination in the ASC is calculated according to the following equation:U = 1.5DL+ 1.8LL (7)In the NBCC the ultimate load is calculated according to the following equation:U = 1.25DL + 1.5LL (8)Where, DL refers dead loads and LL refers to live loads.2.2 Structural design specificationsFlexural Design of a beamBoth codes i.e, ASC and CSA A23.3, follow the ultimate limit state philosophy for designingflexural members. In the ASC code the maximum strain of concrete (έ cu ) in stress block (Fig.1) is 0.003 , while it is taken equal to 0.0035 in the CSA A23.3. Moreover, the stress in stressblock is taken as 0.85f’ c in the ASC and it is taken as α 1 f’ c in the CSA A23.3. In the ASC the stressblock depth (a) is:a=0.85C (9)In the CSA A23.3 the depth of stress block is calculated using the following equation:a=ß 1 C (10)Where,C is the depth of neutral axisß 1 = 0.97-0.0025f’ c ≥ 0.67 (11)έ cu0.85f’ cCaHdAxis of zero strainAs f ybε s ≥ ε yFigure 1- Stress block for a beam422

A COMPARISON OF GENERAL DESIGN AND LOAD REQUIREMENTS IN BUILDING CODES IN CANADA AND SYRIAIn the ASC the strength reduction factor Ω is used to account for the possible variations indimensions of concrete section and placement of reinforcement and other miscellaneousworkmanship items and it is equal to 0.9, 0.7, and 0.85 for bending, axial compression, andshear and torsion, respectively. Thus, the reduced nominal flexural strength (M r ) is calculatedaccording to the following equation:⎛ a ⎞Mr= ΩAsfy⎜d− ⎟ , (Ω = 0.9) (12)⎝ 2 ⎠In the CSA A23.3, the factored concrete compressive strength used in checking ultimate stateshall be taken as φcf 'c(ø c = 0.65) and the factored strength of steel reinforcement is ø s = 0.85.⎛ a ⎞Mr= φsAsfy ⎜d− ⎟ , ( Φ s = 0.85) (13)⎝ 2 ⎠⎛ a ⎞Where, Mn= Asfy⎜d− ⎟ (14)⎝ 2 ⎠Shear design of a beamThe shear due to the applied loads on a beam is usually calculated at a distance d from theinner face of the support in both codes CSA A23.3 and ASC. A simplified approach, in whichthe angle of shear cracks is considered to have a 45 o with the horizontal line, is used in theASC. In CSA A23.3 there are two methods namely the Simplified Method and the GeneralMethod. The Simplified Method is used for flexural members without significant axial tension.The basic design equation for shear capacity of slender concrete beams in both codes is:V ≥ (15)rV fWhere, V f is the shear force due to the factored loads and V r is the factored shear resistancegiven by:V r =V c +V s (16)Where, V c is the shear carried by concrete and V s is the shear carried by the stirrups. The shearcarried by concrete (V c ) is calculated according to the following equations:In the ASC:⎛Vfd ⎞Vc= ⎜0.16f 'c+ 18ρ ⎟wbwd≤ 0.3M⎝f ⎠f 'c(MPa) (17)S =AvfydV − V )(18)(f cIn the CSA A23.3:⎛VfdVcfcwbwdM ⎟ ⎞= ⎜0 .158 ' + 17.2ρ(MPa) (19)⎝f ⎠523

SAMER AL-MARTINIWhere, ρ w is longitudinal steel reinforcement ratio, b w is width of web of member and Mf isapplied moment at a section due to factored loads.AvfydS = φs(20)V −V)(f cWhere, S is stirrup spacing (mm), A v is area (mm 2 ) of stirrup reinforcement within a distance s,and ø s =0.85 is the resistance factor for reinforcing steel.Design of ColumnsThe figure below shows a given strain distribution for a loaded column adopting the ASC .A’ s0.003ε' si0.85 f’ cA’ s f’ s0.85A’ c f’ cA sε sjA s f sFigure 2- Stress block for a column in ASCIn ASC, the strength of a column under truly axially loading is calculated as:P = Ω 0 .85 f ' A − A + f A(21)r o[ ( ) ]cgstystΩ = 0.7 (axial load)A g = gross area of the section (concrete + steel)f y = yield strength of reinforcementA st = total area of reinforcement in the cross sectionTo account for the un-expected moment, the code specify that the maximum load in columnmust not exceed:Pr , max= 0. 8P rofor tied column.Pr , max= 0. 85P rofor spiral column.The figure below shows a given strain distribution for a loaded column according toCSA A23.3:0.0035α 1 f’ cA’ s f’ sA’ sε' α si1 A’ c f’ cA sε sjFigure 3- Stress block for a column in CSA A23.3A s f s624

A COMPARISON OF GENERAL DESIGN AND LOAD REQUIREMENTS IN BUILDING CODES IN CANADA AND SYRIAThe strength of a column under truly axially loading is [4]:Pr= [ φcαf 'c( Ag− Ast) + φsfyAst]o 1(22)α 1 f’ c = maximum concrete stressesφc, φs= material strength reduction factorsTo account for the un-expected moment, the code specifies that the maximum load in columnmust not exceed:Pr , max= 0. 8P rofor tied column.Pr , max= 0. 85P rofor spiral column.Thus, it can be observed that the differences between the two codes are in taking the maximumconcrete stresses (stresses block) and in the material reduction strength.Design of slabsThe thickness in ASC of a slab can be calculated from a table based on the type of a slab (oneway or two ways) and its dimensions. For a regular building having LL ≤ 5KN/m 2, the momentdistribution on each slab can be calculated using one of the following methods:The Moment Distribution Factors Method, where the distribution factors on each slab spans areobtained from tables considering the location of each slab.2M = α Awa(23)aWhere, M a is the moment on short span of slab, a A is moment distribution factor, w is factoredload, and a is the short side dimension. The same equation is applied for the other span of theslab (long span) with different moment distribution factors and span dimension.The Strip Method considering interior or exterior support for negative and positive moment.The factored static moment of a rectangular slab can be calculated:2M o 2= μ2wL2(short span (L 2 )) (24)Mo1 = μ1Mo2(long span (L 1 )) (25)L2Where, µ 1, µ 2 are factors obtained from a table considering μ = .L1Negative moment and exterior support: M L1 = 0.3M o1 , and M L2 =0.3M o2 .Negative moment and interior support: M L1 = 0.6M o1 , and M L2 =0.6M o2 .Positive moment: M L1 = 0.75M o1 , and M L2 =0.75M o2 .Reinforcement is designed for the moment considering the section is rectangular.The thickness of a slab in CSA A23.3 is calculated using equations specified in the code fordifferent cases. The Direct Design Method can be applied if the following conditions aresatisfied [4]:long spanMax ≤ 2 (measured centre to centre of supports) .short spanThe column offsets are less than 20% of the span.725

SAMER AL-MARTINIThere is a minimum of spans in each direction is three.The factored live load must not exceed two times the factored dead load.The total static moment for each slab is calculated using the following equation:2wfl2alnMo= (26)8Where, w f is factored load per unit area; l n is clear span between columns; and l 2a is transversewidth of strip.This moment is distributed on the beams and slab spans using factors given in a table providedby the code (CSA A23.3).It should be noted that reinforcement in both codes is designed for the moment considering thesection as a rectangular beam.3. SUMMARY AND CONCLUSIONSThe paper attempted to investigate the differences in general design and load requirements inBuilding Codes in Canada and Syria used for the Design and Execution of Reinforced ConcreteBuilding Structures. The Arabic Syrian Code for Design and Execution of Reinforced BuildingStructures (ASC) is used in Syria to design a building while, in Canada, the National BuildingCode of Canada (NBCC) for loads specification and the Canadian Standard Association Code(CSA A23.3) for reinforced concrete specification are used for designing a building. The papershowed that the Syrian code has increased the factor of safety by adopting higher values ofload factors. Also, the live loads for rooms and stairs in the ASC are higher than that specifiedin NBCC. It can be argued that the ASC is more conservative than the NBCC which is likelydue to the fact that Syria lies on an active seismic zone.4. REFERENCES[1] ASC, Arabic Syrian Code for Design and Execution of Reinforced BuildingStructures. (2004)[2] NBCC, National Building Code of Canada. (2007)[3] CSA A23.3, Canadian Standard Association Code. (2003)[4] MacGregor, G. J., and Bartlett, F. M., Reinforced Concrete Mechanics and Design,1 st ed, Prentice Hall Canada Inc. (2000)826

AHU J. of Engineering & Applied Sciences 3 (2) : 27-50 (2011)© 2010 ALHOSN UniversityANALYSIS OF SOIL MEDIA CONTAINING CAVITIES ORTUNNELS BY THE BOUNDARY ELEMENT METHODOmar al-Farouk S. al – Damluji 1, Mohammed Y. Fattah *2Rana A. J. al-Adthami 31. Former Professor, Civil Eng. Dept., College of Eng., University of Baghdad, Iraq.2. Assistant Professor, Building and Construction Engineering Department, University of Technology,Baghdad, Iraq.3. Former graduate student, Civil Eng. Dept., College of Eng., University of Baghdad, IraqABSTRACT: In the design of tunnels to be constructed in urban areas, it is necessary to estimate the magnitudeand distribution of the stresses and settlements that are likely to occur due to a particular design and constructiontechnique. The main factors that greatly affect the stresses and deformations around tunnels and undergroundexcavations are the shape, dimensions, depth of opening below the ground surface, distance between the openingsand the kind of supports.In this paper, a study of the effect of different parameters was conducted by considering a cavity of 4meters diameter under a constant surcharge load of 50 kN/m 2 . These parameters are:1. depth below the ground surface Z o ,2. eccentricity of a cavity locations from the centerline of surface loading, and,3. distance between cavities K.A computer program for analysis by the boundary element method is used for the determination of thestress and deformation fields around two cavities with the above mentioned parameters. The soil is assumed to behomogeneous, isotropic and a linearly elastic medium containing two openings.It was found that a marked increase of stresses takes place as the cavity approaches the ground surfaceand the stress distribution is very sensitive to the depth variation compared with the case of no-cavity condition.The maximum stresses occur at the haunches of the tunnel rather than at the crown.The vertical displacement of the soil medium increases by decreasing the distance between the adjacentopenings. In general, small values of K/D ratios (where K is the distance between two cavities and D is thediameter of one cavity) should be avoided to hinder rapid increases in the stress concentration.KEYWORDS: Boundary element, Soil, Cavity, Tunnel. C1. INTRODUCTIONThe boundary element method (BEM) has become one of the most powerful tools for thenumerical study of different engineering problems. The comparison of the main features of thismethod with those of the finite element method (FEM) has occupied many pages in thespecialist literature sine the initial development of BEM.An important feature of the BEM is that the functions that represent essential andnatural boundary conditions (potential and flux in potential theory and displacements andstresses in elasticity theory) which are the basis of the method, consequently beingapproximated in an independent form, their coordinates remaining as independent variables ofthe formulation.In spite of non-symmetric and fully populated character of the matrices associated toBEM, it must be pointed out that the size of the system of equations, defined by the stiffnessmatrix K, is always smaller than in the finite element method (FEM) approach, for a similar__________________________* Corresponding Author.E-mail : myf_1968@yahoo.com27

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIdegree of dicretization. The ratio between the sizes of the matrices in the two methods willdepend on the geometry under consideration, and in particular on the proportion of theboundary (area in 3D and length in 2D problems) to the domain (volume in 3D and area in 2Dproblems). The smaller this proportion (the greater the domain covered by a certain boundary),the greater the ratio between the size of the matrices of FEM and BEM (the more favourablethe use of BEM), [4].2. ANALYSIS USING THE BOUNDARY ELEMENT METHODAlthough the finite element techniques have been used in so many practical problems, theboundary formulations appear as an alternative technique that, in many cases, can providemore reliable or economical analysis. Even with automatic mesh generation techniques, thefinite element method has not found widespread application to tunneling problems because ofthe data preparation problems and considerable computer time requirements.The input data requirements of the boundary element method are considerably less thanthese of the finite element method since only the boundary need to be discretized. Unlike theFEM, the BEM can model the boundaries at infinity without truncating the outer boundary atsome arbitrary distance from the region of interest.After the numerical treatment of the integral equations, we end up with a system ofequations. In contrast to the FEM, the coefficient matrix is fully populated and unsymmetrical.Standard Gauss elimination can be used but, for large systems, the storage requirement and thecomputation times may be reduced considerably by iterative solvers, such as conjugategradient methods. Here we also find that the method is “embarrassingly parallelisable” i.e. thatexcellent speed up rates can be achieved with special hardware. The primary results obtainedfrom the analysis are values of displacement or traction at the boundary depending on theboundary condition specified. In contrast to the FEM, primary results do not include values inthe interior of the domain but these are computed by post-processing, [2].2.1 Boundary Element EquationsIsotropic field problems have a governing equation. From the mathematical analysis, thecorresponding boundary integral equation with respect to a source point (x i , y i ), can be writtenas follows (Brebbia, 1978):**C iui+ ∫ q udΓ = ∫ u qdΓ + bi(1)ΓΓwhere: C i is a constant depending on the location of the point within the domain Ω,u i = u(x i , y i )*and bi = b(xi, y i ) = ∫∫ φ(x,y)u (x − xi, y − y i ) dxdy (2)ΩIf the piecewise-discretization concept, which is usually used in finite element analysis,is applied here, then the boundary Γ may be divided into a number n e of sub-boundaries,connected by boundary points, as shown in Figure (1).28

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODYΓ..Γ e. . ..Ω .. . . .NodesElementFigure (1) – Boundary discretization.XIf f (x, y) is a continuous function defined over Γ, then it can be deduced that:ne⎡∫ ∑ ∫Γ = Γ ⎥ ⎥ ⎤f dΓ = ⎢ f dΓ(3)e 1⎢⎣e ⎦Applying the boundary-discretization concept, then equation (1) can be rewritten in thefollowing form:ne⎡⎤ n*e ⎡⎤*Ciui+ ∑ ⎢ ∫ q (x − xi,y − yi)u( Γe)dΓ⎥= ∑ ⎢ ∫ u (x − xi,y − yi)q( Γe)dΓ⎥+ bi(4)e= 1⎢⎣Γe⎥⎦e= 1⎢⎣Γe⎥⎦where u (Γ e ) and q (Γ e ) may be approximated by means of interpolation expressions in terms oftheir values at source boundary nodes.Using such a discretization technique, it is possible to represent a boundary integralequation by means of a simple algebraic equation in terms of the boundary nodal values offield function parameters.Full description of the boundary element formulation is found in El-Zafarany [4], Parisand Canas [5] and Al-Adthami, [1]. All explicit expressions for the fundamental solutionparameters given here are found in Al-Adthami, [1].2.2 Computer ProgramA computer program based upon the theory of the two-dimensional solid continuum mechanicsproblems of the boundary element method with constant elements is coded in FORTRAN 77and introduced herein. The program can deal with plane stress and plane strain problems withsurface and domain loadings.3. CASE OF TWO CAVITIESFigure (2) shows a schematic representation of the problem to be studied for four values ofdepth/diameter ratios (Z o /D = 1, 1.5, 2 and ∞). The origin of coordinates (X and Y) isconsidered at the center of the ground surface.29

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIFigures (3) and (4) show the distribution of vertical and horizontal stresses along thecenterline of the surface loading (line I-I in Figure 2). The stresses in these figures arenormalized by dividing each stress by the initial overburden stress (P).It is obvious from these figures that the vertical stress distribution decreases with theincrease of Z o /D ratio and the maximum value of horizontal stress decreases as Z o /D increases.It is also noticed that the values of (σ y /P) and (σ x /P) become constant at a depth of (Y/D = 5).Therefore, the depth in the figures is restricted to five diameters only.Figures (5) and (6) show the horizontal and vertical stress distributions along ahorizontal line 1.0 m below the ground surface (line II-II in Figure 2). These figures indicatethat there is a big disturbance in the stress distribution when Zo/D≤ 2 as the cavities approachthe ground surface. It is also evident from these curves that the heave effect starts to appear at adistance equals to the tunnel diameter D away from the centerline of the surface loading.Figures (7) and (8) show the distribution of horizontal and vertical stresses along a line7.0-meter away from the centerline of the load width, (line III-III in Figure 2). It is noticed thatdisturbance in the stress distribution extends to a depth of about (Y/D = 3). Below this depth,the stress distribution tends to be uniform.Figures (9) and (10) show the contour lines for four values of Depth/Diameter ratios(namely, Zo/D = 1.0, 1.5, 2.0 and ∞). The contours are drawn for vertical displacement andvertical stress distributions, respectively. These figures reveal that the highest values ofdisplacements and stresses concentrate in the space between the cavities.4. INFLUENCE OF ECCENTRIC LOCATIONS OF CAVITIESFigure (11) shows a schematic representation of the problem to be studied for five values ofeccentricity/diameter ratios (e/D = 0, 1, 2, 3 and ∞).Figure (12) shows the vertical displacement (Uy) distribution along the ground surface.It can be noticed from this figure that the effect of the cavity on the surface settlement must betaken into consideration if e/D < 3 and neglected otherwise. This figure also provides designerswith some guidance regarding the influence of the cavity location on the settlement of theground surface.Figure (13) shows the vertical stress distribution over a line 3 meters below the groundsurface (line IV - IV in Figure 11). From this figure, it is noticed that when the cavity is about4.0 m away horizontally from the centerline of the surface loading (e/D = 1), σ y on this lineincreases by about 5% from the case of no-cavity under the center of the surface loading.While for other values of e/D ratio, σ y decreases. Also, heave stresses appear on the area abovethe cavity on this line.Figures (14) and (15) illustrate the variation of σ y and σ x on the centerline of thesurface loading. The effect of the cavity can be neglected in computing the stress values on thisline when e/D

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODFigure (16) shows the variation of vertical displacement over a line 1 m below theground surface (line II-II in Figure 11). It is evident from this figure that the concentriclocation (e/D = 0.0) of the cavity is the critical location which results the largest displacementon this line. Also, with the increase of e/D ratio, the settlement decreases.III.IIFigure (2)-Schematic views of surface load-soil-cavities system.24 mP= 50 kN/m 2B= 4 m6 m 4 mII8 mD = 4 m K= 4 m D = 4 m7 m24 m 24 mIII1 mII31

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIσ y /P0 0.2 0.4 0.6 0.8 1 1.20.00σ x /p-0.2 -0.1 0 0.1 0.2 0.3 0.40.00.500.51.001.01.501.5Y/D2.002.50Y/D2.02.53.003.03.503.54.004.505.00Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D=∞4.04.55.0Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D= ∞Figure (3) -Vertical stress distributions alongline I-I.-0.10.00.1Figure (4) - Horizontal stress distribution alongline I-I.X/D0 1 2 3 4 5σx/p0.20.30.40.5Z o /D = 1 .0Z o /D = 1 .5Z o /D = 2 .0Z o /D = ∞Figure (5)-Variation of horizontal stresses along line (II-II).32

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODX/D-0.250 1 2 3 40σy/P0.250.50.751Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D= ∞Figure (6)-Variation of vertical stresses along line II-II.Y/D0.00.51.01.52.02.53.03.54.04.55.0σ x /P-0.1 -0.05 0 0.05 0.1 0.15 0.2Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D=Figure (7)-Horizontal stress distribution alongline (III-III).∞Y/Dσ Y /P0 0.05 0.1 0.15 0.2 0.250.00.51.01.52.02.53.03.54.04.55.0Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D=Figure (8)-Vertical stress distribution along line(III-III).∞33

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIElevation (m)Elevation (m)24211815129632421181512Elevation(m)Elevation (m)9630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6Distance (m)8 10 12 14 16 18 20 22 24(a)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2Distance (m)4 6 8 10 12 14 16 18 20 22 24(b)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4Distance (m)6 8 10 12 14 16 18 20 22 24(c)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(d)34

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODElevation (m)Elevation (m)242118151296324211815120-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24963Distance (m)(a)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(b)Elevation (m)2421181512Elevation (m)9630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4Distance (m)6 8 10 12 14 16 18 20 22 24(c)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(d)35

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIThe vertical stress distributions over a horizontal line passing through the centers of thecavities (line III-III in Figure 11) are illustrated in Figure (17). Over these lines, there is a rapidincrease of the vertical stress at the points adjacent to the cavity. Also, σ y is higher when thecavity is centered directly under the surface loading. However, it can be noticed from thisfigure that the variation of e/D ratio has a little effect on the state of stress over this line, exceptfor the region adjacent to the cavity.IIIVIII24 mIP= 50 kN/m 24 mZo =8 me = 4 me = 8 me = 12 m24 m 24 mIFigure (11)-Schematic views of surface load – soil – cavity systemhorizontaleccentricity from load centerline.1 mII3 mIVIII36

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODUy (m)X/D-5 -4 -3 -2 -1 0 1 2 3 4 50.00000.00020.00040.00060.00080.00100.00120.0014e/D=0e/D=10.0016e/D=20.0018e/D=3e/D= ∞0.0020Figure (12)-Vertical displacements on the surface.σy/PX/D-5 -4 -3 -2 -1 0 1 2 3 4 50.000.050.100.150.200.250.300.35e/D=0e/D=10.40e/D=2e/D=30.45e/D= ∞0.50Figure (13)-Variation of vertical stresses along line IV-IV.Figures (18) and (19) show the contour lines for four values of eccentricity/Diameterratios (namely, e/D = 0.0, 1.0, 2.0 and ∞). The contours are drawn for vertical displacementand vertical stress distributions, respectively. It can be noticed that when (e/D ≥ 2), the effectof eccentricity of cavity vanishes.37

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMI5. INFLUENCE OF DISTANCE BETWEEN CAVITIES “K”Figure (20) shows a schematic representation of the problem to be studied for five differentvalues of K/D ratios (K/D= 0.5, 1, 2, 3 and ∞), where K is the distance between two cavities.The settlement curves of the ground surface loading–soil-cavities system are shown inFigure (21). From this figure, it is evident that the surface disturbances due to cavity presencecan be neglected at a distance exceeding 3D away from the centerline of the surface loading.Also, it can be noticed that as the distance K increases, the surface settlement decreases. For K≥ 3D, the effect of the two cavities on the surface settlement can be neglected. The horizontaldisplacement on the ground surface is shown in Figure (22).σ y /Pσ x /PY/D0 0.2 0.4 0.6 0.8 10.00.51.01.52.02.53.03.54.04.55.0∞e/D = 0e/D = 1e/D = 2e/D = 3e/D = ∞Y/D0.00.51.01.52.02.53.03.54.04.55.0-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5e/D=0e/D=1e/D=2e/D=3 ∞e/D= ∞Figure (14)-Variation of vertical stresses alongline I-I.Figure (15)-Variation of horizontal stressesalong line I-I.38

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODUy (m)X (m)-25 -20 -15 -10 -5 0 5 10 15 20 250.00000.00020.00040.00060.00080.00100.00120.0014e/D=0e/D=1e/D=20.0016e/D=3e/D= ∞0.0018Figure (16) – Variation of vertical displacements along line II-II.X/Dσy/P0.00.10.10.20.20.30.30.40.40.50.5-5 -4 -3 -2 -1 0 1 2 3 4 5e/D=0e/D=1e/D=2e/D=3e/D= ∞Figure (17)-Vertical stress distribution along the horizontal axis of cavities.Figures (23) and (24) show the horizontal and vertical stress distributions along thecenterline of the surface loading (line I-I in Figure 24). It can be noticed from these figures thatdecreasing the distance K results in an increase in both σ x and σ y along this line.39

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIFigure (25) shows the vertical stress distribution along a line passing through thehorizontal centerline of the cavities (line II-II in Figure 20). It is evident from this figure thatthe vertical stress increases by decreasing the distance between the adjacent cavities. Also, it isnoticed that the stress concentration at the region between cavities centers decreases byincreasing the distance “K”.Figure (26) shows the horizontal stresses distribution along a line passing through thehorizontal centerline of the cavities (line II-II in Figure 20). It is noticed from this figure thatthe horizontal stress decreases by increasing the distance between cavities.Figure (27) shows the vertical stress distribution over a line 5.0 m below the groundsurface (line III-III in Figure 20). It can be noticed that by decreasing the distance “K”, a bigdisturbance in the vertical stress occurs.Figure (28) shows the horizontal stress distribution over a line 5 meters below theground surface (line III-III in Figure 20). It can be noticed that by increasing the distancebetween cavities, there is a little disturbance in σ x .Figures (29) and (30) show the contour lines for four values of distance/diameter ratios(namely, K/D = 0.5, 1.0, 2.0, and ∞ ). The contours are drawn for vertical displacement andvertical stress distributions, respectively.It can be noticed that when (K/D = 1.0), the maximum displacements and stresses takeplace along the centerline of the problem.Elevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(a)Elevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(b)40

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODElevation (m)Elevation (m)Elevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 2424211815129632421181512963Distance (m)(c)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 2424211815Elevation(m)12963Distance (m)(d)Figure (18) -Variation of vertical displacements in (mm) for:(a) e/D = 0, (b) e/D = 1, (c) e/D = 2 and (d) e/D = ∞.0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(a)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(b)41

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIElevation (m)Elevation (m)242118151224211815129639630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(c)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(d)Figure (19) -Variation of vertical stresses in (kN/m 2 ×10) for:(a) e/D = 0, (b) e/D = 1, (c) e/D = 2 and (d) e/D = ∞.42

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODIIIII24 mIP= 50 kN/m 26 mZo= 8B= 4 m24 m812 m24 m 24 mFigure (20) – Schematic views of surface loading – soil – cavities system.IIIII6. CONCLUSIONSFrom the previous work, the following conclusions have been reached:1. A marked increase of stresses is found as the cavity approaches the ground surface and thestress distribution is very sensitive to the depth variation compared with the case of nocavityconditions.43

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMI2. The maximum stresses occur at the haunches of the tunnel rather than at the crown.3. For the circular cavity that is considered in this work, with increasing the depth below theground surface (Z o /D > 3), the surface settlements do not exceed 6 % from those obtainedfor the case of no-cavity condition.4. The vertical displacement of the soil medium increases by decreasing the distance betweenthe adjacent openings.5. In general, small values of K/D ratios (where K is the distance between two cavities and Dis the diameter of one cavity) should be avoided to hinder rapid increases in the stressconcentration.6. The region between the two adjacent cavities is more influenced by the distance “K”variation than the outer regions.Uy (m)0.00000.00020.00040.00060.00080.00100.00120.00140.00160.00180.0020X (m)0 5 10 15 20Figure (21)-Vertical displacements on the ground surface.X (m)K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞0.000000 5 10 15 20Ux (m)0.000050.000100.000150.000200.000250.000300.00035K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞Figure (22)- Horizontal displacements on the ground surface.44

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHOD7. REFERENCES:[1] Al-Adthami, R. A. J., (2003). “Applications of the Boundary Element Method toSoil Media Containing Cavities”, M.Sc. thesis, University of Baghdad.[2] Beer, G., Smith, I. and Duencer, C., (2008). "The Boundary Element Method withProgramming", Springer-Verlag Wien New York.[3] Brebbia, C. A., (1978). "The Boundary Element Method for Engineers", PentechPress, London.[4] El-Zafrany, A., (1992), “Techniques of the Boundary Element Method”, EllisHorwood, New York.[5] Paris, F. and Canas, J., (1997). (Boundary Element Method-Fundamentals andApplications), Oxford University Press.APPENDIX I0.00.51.01.5σ x /Pσ x /P-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5σ y /P0.0 0.2 0.4 0.6 0.8 1.00.00.51.01.5Y/D2.02.53.0Y/D2.02.53.03.53.54.04.55.0K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞Figure (23)-Horizontal stress distributionalong line I-I.4.04.55.0K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞Figure (24)-Vertical stress distributionalong line I-I.45

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMI0.70.60.50.4K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞σy/P0.30.20.10.00.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5X/DFigure (25)-Vertical stress distribution along line II-II.0.150.100.050.00σx/PK/D=0.5-0.05K/D=1.0-0.10K/D=2.0-0.15K/D=3.0K/D= ∞-0.200.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5X/DFigure (26)-Horizontal stress distribution along line II-II.46

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHOD0.60.50.4K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞σy/P0.30.20.10.00.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5X/DFigure (27) – Vertical stress distribution along line III-III.0.200.150.10K /D =0.5K /D =1.0K /D =2.0K /D =3.0K /D = ∞σx/P0.050.00-0.05-0.100.0 1.0 2.0 3.0 4.0X/DFigure (28) – Horizontal stress distribution along line III-III.Etlevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4Distance (m)6 8 10 12 14 16 18 20 22 24(a)47

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMIElevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(b)Elevation (m)Elevation (m)24211815129630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 242421181512963Distance (m)(c)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(d)Figure (29)-Variation of vertical displacements in (mm) for:(a) K/D = 0.5, (b) K/D = 1, (c) K/D = 2 and (d) K/D = ∞.48

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHODElevation(m)Elevation (m)Elevation (m)242118151224211815129639630-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(a)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 242421181512963Distance (m)(b)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 2424211815Elevation(m)12963Distance (m)(c)0-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance (m)(d)Figure (30)-Variation of vertical stresses in (kN/m 2 ×10) for:(a) K/D = 0.5, (b) K/D = 1, (c) K/D = 2 and (d) K/D = ∞.49

AHU J. of Engineering & Applied Sciences 3 (2) : 51-72 (2011)© 2010 ALHOSN UniversityGUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITYTOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSWITH PRACTICAL AND INDUSTRIAL CASE STUDIESM. El-Gammal (Sr.) 1 , H. El Naggar 2* , M. M. El- Gammal (Jr.) 11 Department of Naval Architecture and Marine Engineering, Faculty of Engineering, University of Alexandria,Egypt.2 Civil Engineering Department, ALHOSN University, P.O. Box: 38722, Abu Dhabi, UAE.ABSTRACT: In a progressive environmentally conscious world gearing towards sustainability, pipelinedesigners, builders, and operators are faced with an escalating number of complex limitations and restrictions; allfocused on increasing safety standards and reducing the risk of any potential pollution.The main objective of the current paper is to propose a new technique for risk estimation aiming at reducingbursting, explosions, fires, and corrosion of pipelines. Also, to demonstrate the new estimated risk concept byintroducing analysis of various cases of pipeline accidents. So, the paper serves clearly in pipeline safety measuresand pipelines integrity management. It is important to realize the meaning of pipeline integrity by managing safetyas well as carrying out risk analysis through implementing the Asset Integrity Management (AIM) concepts. Thepipeline problems could be definitely reduced as well as serving without non-expected or non-predicted hazardsagainst loss in property, loss in lives, or loss of the pipeline itself.This paper defines risk as applied to pipeline integrity by estimating the consequences which is being based onroot cause analysis. The latter is found to depend on several surrounding and environmental factors. Practicalexamples from real industrial life problems have been investigated and demonstrated in views that the applicationof the root cause analysis, RCA, together with a scheme of AIM will reduce the recurrence of those accidents oncethe real cause has been known and properly maintained.Keywords: pipeline, sustainability, Asset Integrity Management (AIM), Root Cause Analysis (RCA)1. INTRODUCTIONOver the last few decades, the oil and gas industry has witnessed an unprecedented extensivedevelopment. Billions of dollars have been spent on construction of pipelines and infrastructureprojects. Thus, quantifying the risk of potential problems associated with the operation of theseinfrastructures is of paramount importance for all stakeholders.Traditionally, academicians used to teach their students only strength governed designs andfacts of how to avoid catastrophic pipelines accidents. Nevertheless, in real practice due to thewrong practical treatment of the pipeline or by applying the wrong alternative solution offeredand assumed within a design philosophy based on similar problems that may be far differentfrom what safety seniors say [1-3]. Anyway one of the best advises the well experiencedseniors in fields of pipelines, whom, used to recommend to their juniors that: “do not play withthe pipeline, especially if it were containing flammable materials, such as gas and oil.” Butinstead juniors must be aware in prompt of how to deal with practical implementations ofsolutions. This is to be formulated through real gaining of practice as well as the well flow ofinformation granted and collected from expert seniors of some of the vast remarkabletheoretical and practical experience [4].____________________________________________* Corresponding Author.Tel.: +971 2 4070529, E-mail : h.elnaggar@alhosnu.ae51

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)Recent pipeline accidents [5-10] show that there will be too much work needed to safeguardimminently our pipelines against fire, bursting and explosion hazards that will produce panicand thus the loss of property as well as resulting in the more expensive tragedy the loss oflives.The intent of the present paper is to highlight reasons and causes of pipeline failures due tocorrosion hazards. Furthermore to define the Root Cause Analysis “RCA” that must be basedin turn on risk. The probabilistic approach that implies the calculations of consequences formcontingent plans of safety through implementing the types of maintenance necessary to becarried out right in time. Deploring the monitoring and implying the quality auditing topromote reduction in downtime and to improve pipeline integrity as well as will deploying thelifetime at large will aim to reduce the leak before break and thus will reduce the risk ofcatastrophic explosion.Definitely there will be no one unique solution to the problem of pipeline integrity and safetyhazard prevention. But instead the designer ought to cover as much as he could frominformation from similar trouble shooting cases and then he could tailor the solution thatdefinitely will reduce the risk. Yet this reliable solution again needs vast experience that somemay be lacking. Thus the best solution and the better utilization of handling pipelines integrityproblem shall be implemented and tabulated for any project while it is still in the paper stage.Alternative solutions must also be offered ready to be applied without trial and error butmathematically modeled and virtually implemented. The trial and error depends on luck morethan engineering matters and technical assessments and thus, it will be waste of time as well aswaste of money, waste of efforts and waste of property to apply that concept. So, it would bemore reliable to rely on RCA applied in pipeline integrity, if the material, the environment, aswell as the operators are all the same or nearly so.2. DOES THE ASSET INTEGRITY OFFER THE BEST PIPELINE SOLUTION?2.1 Definition and measures of integrityDefinition of the word “Asset” means evaluation, while the word “Integrity“ means unbrokencompleteness or totality [11]. That means in simple terms that Asset Integrity means the unityof evaluation for the wholeness of completeness. It is considered as the tool for managementintegrated solution offering the best of the better of choosing from the best design, betterchoice of materials and the better available manufacturing processes as well as the bestassembly sequences and procedures for a pipeline. That is being assumed to be serving withinan extreme aggressive environment. Thus it is a toolkit for reducing trouble shooting withbetter care to develop successful means to better managing the surrounding environment andbetter control of utilization of all production aspects in pipelines projects. This includesimproving in the estimated lifecycle through better inspection intervals of monitoring. Thusthis toolkit can give the management an overview leading to efficient evaluation of the projectand reducing sudden catastrophic failures, by reducing the accidents in pipelines. AssetIntegrity is anything of a value that incorporates owns that is held in firm adherence to a code.52

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTS2.2 Benefits and objectives from application of asset pipeline integrity in oil and gasfields:In the oil, gas and power industries mitigating risk to Accidental Probablistic Risk Levels is notonly vital to ensure compliance with legal requirements, but also reducing significant everydaylosses:• Improving safety alerts and environmental integrity through extending pipeline lifecycle,• Optimizing maintenance intervals and lower maintenance costs as well as lessunplanned downtimes thus improving lifecycle and thus increrase productivity• Reducing ligament thickness - metal loss due to corrosion deterioration and degradationproblems,• Machining slits (parent metal, seam weld, heat affected zone) defects can all bemonitored and eliminated,• Reducing the probability of fatigue cracks thus can control the sudden hazard events,• Identify and reduce hazards due to dents,dent/slit combination and mechanical damagewill also be under control.2.3 How and why do Asset integrity being manipulated within the process of safetystandards?Asset Integrity is committed to prevent incidents that put people, neighbors, the environmentand the facilities at risk. Therefore, asset integrity is the safety process which gives thedecision maker the assurance that the facilities are well designed, safely operated and properlymaintained, [12]. What is meant by Asset Integrity Approach and how it could be more usefulin pipeline applications? Asset Integrity approach in pipelines integrity practical problems hasbeen proposed from two or more decades [13-15] and denoted in Figures 1-a and 1-b. Figure 1-a gives the triangle of management decision success applied within asset integrity in fields ofpipeline projects. It is based on root cause analysis which method can be applied to prevent therecurrence of the bad event in pipeline once again. Figure 1-b explains how the flow ofinformation in the building up of correct decision is based on asset integrity, while Figures 1-cgives the different uses and the main pipeline applications now in current use. From that figureone can note the importance of maintaining pipelines. The figure as seen describes at its top thedifferent types of pipelines currently applied. At the middle it demonstrates the different usesof pipelines in our wells, within different refineries’ departments, then to transportationfacilities and ships to transfer oil, gas and their products using ships. The store tanks at the endof the transportation must be fitted also with pipes of different sizes, varieties in materials. Allare to be serviced as terminal tanks for the end process of transportation. Then the feedingpipes to the industrial facilities are to be monitored to prevent environmental safety hazards.The last in the important cycle of pipelines harmony are those used to feed domestic uses inhouses for warming, cooking and all other very important uses in the house hold equipment.The lower portion of Figure 1-c shows the different categories of pipelines in various53

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)engineering fields of practice. Those figures are aimed at demonstrating the importance of riskbased criteria.Fig. 1-a: Asset integrity applied with RCA will lead to better utilization of pipeline [13-15]Fig. 1-b: Pyramid of asset integrity the top is Asset Integrity at the base Safety of publicinterests and in between the inspection which means close supervision and proper maintenanceof a pipeline project.54

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSFig. 1-c: Practical and industrial uses of pipelines [16-19]Figure 2 [23 & 24] shows the four steps for Risk Cost Identification and Assessment. From thatfigure that the first step in any model of pipeline risk assessment is being divided into severalstages. The first stage is how to identify the cause and to recognize the hazard reason. Thesecond stage is how to develop the risk assessment of that hazard if it were happened. The thirdstage in the model is how to devise a proper solution to control the hazard and itsconsequences. The fourth step is how to be able to estimate the cost of benefit associated withthe involved savings of lives and properties against the determined risk. The fifth and finalstage is how to demonstrate and to recommend a tailored decision for the management to take.Of course all steps are to be based on monitoring times, intervals and capabilities of theinspectors.55

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)Generally the basic decision making is liable to bench marking and thus the success can beassessed by the use of KPI “Key Performance Indicator”. In case if there is alternative differentsolutions to deal with the same hazard then the KPI must be assessed for each alternative andby then the right measured value can give guidance to the management to decide which is thebest alternative to be followed and thus which is being recommended.Figure 2: Steps followed in Risk Identification [23]3. RISK ANALYSIS IN PIPELINE INTEGRITYRisk assessment provides a structured basis for pipeline operators to identify hazards and toensure risks being ultimately reduced to appropriate levels in a cost-effective manner. Theregulations applying to offshore operations in the pipelines’ industry require operators toundertake risk assessment in order to identify appropriate measures, as far as is reasonablypracticable, to protect people against accidents. It may well be that the use of Quantitative RiskAssessment (QRA) for Temporary Refuges has given the impression that risk assessment issynonymous with QRA [22-24]. A risk assessment and management process that is focused onloss of containment of pressurized equipment in processing facilities, due to materialdeterioration is called by Risk Based Analysis [22]. These risks are managed primarily throughequipment inspection. Root Cause Analysis ‘RCA” has two important roles in pipelineintegrity management:1. Identify Operational problem and issues2. Identify consequences of a failure2.1. Includes criticality –if equipment goes down, what are the effects on the system2.2. Share consequences of past failures56

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSFigure 3-a [22], shows the 6x6 ISO Risk Matrixes. As seen in this figure the likelihood of abad event goes down starting at one for the lowest and goes to six at the utmost for the rareevent. The six categories of probabilities of the event are two for the occasional, three forseldom, four for unlikely and five for remote. The impact and the consequences of the sameevent are defined by one for Catastrophic event, two for the severe, three for the minor, fourthe minor, five for the moderate and finally six for the incidental. Each will be having differentvalues of weight factors as seen in the matrix. The weight starts with a value of unity for thelikelihood and the catastrophic consequences and goes up to the value of 10 for the rare eventand the incidental consequences. The ISO matrix as such is composed of 6 events x 6 impacts.Nevertheless, the ISO matrix can be reduced to be 5x5 matrix as shown in Figure 3-b.1 Likely2 Occasional3 Seldom4 Unlikely5 Remote6 RareDecreasing Likelihood6 5 4 3 2 17 6 5 4 3 28 7 6 5 4 39 8 7 6 5 410 9 8 7 6 510 10 9 8 7 6Consequence IndicesDecreasing Consequence/Impact6 5 4 3 2 1Incidental Minor Moderate Major Severe Catastrophic3-a: 6x6 ISO Risk Matrixes5 4 3 2 16 5 4 3 27 6 5 4 38 7 6 5 49 8 7 6 53-b: 5x5 ISO Risk MatrixesFigure 3: ISO Risk Assessment Matrix [22]57

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)4. STANDARD QUANTITAIVE RISK ASSET (SQRA)As has been explained earlier that the calculated risk should be compared with a constraintvalue, named here by “Standard Quantitative Risk (SQR)”, to know whether the event is anexpected, tolerated, predicted or a non-predicted one. Most of the Regulatory Bodies andClassification Societies have put forward risk motivation studies. In doing so, they havesuggested constraint values quoted here as standard risk values. Yet those standard values cangenerally be applied to any of the pipeline integrity problems.5. SUGGESTED TECHNIQUE FOR RISK ANALYSIS APPLIED WITHIN PIPELINESThe purpose of this work is to furnish a guidance of proposing a risk assessment method forpipelines through applying simpler techniques and methods leading to better end of riskassessment. The qualitative and semi-quantitative techniques have been applied to definestandard risk values in accordance to the concerned Classification Society. It explains riskassessment technology as it might apply to pipeline operations, emphasizing techniquesappropriate to pipeline hazards. Quality Risk Assessment “QRA” has a role in some pipelineapplications, since it demonstrates how the wider range of techniques can help operatorsperform a suitable and sufficient risk assessment, and demonstrate that risks are As Low asReasonably Practicable (ALARP) [22]. Figure 4 gives the flow diagram leading to theassessment of the integrated hazard in pipeline safety management.58

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSFigure 4: Assessment of Integrated Hazard Identification in Pipeline Safety DecisionsThe prediction criteria is such that if the estimated risk exceeds the standard value then theaccident shall be considered as to be expected, but if the estimated value is less, the accident issaid to be non-expected but happened.Equation (1) is based on the two risk dividends. The first is known to be the frequency or theprobability of the event. The second is known as the consequences and impacts from thatevent. Figure 5 highlights the sequence to be followed in the calculations of risk as shown byequation (1).59

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)Risk = P E * T C (1)Where,P E is the frequency probability of the event E,T C is the summation of consequences of the resulted impacts of that event as denoted by eq.(2).The total impact of the consequences of an event is thus that denoted by equation (2) and TableI.where,T C = LV + LP + S + E + Q + T + O + I (2)LV presents the panic due to the loss of lives,LP presents the panic due to the loss of properties,S presents the panic due to the Safety,E presents the panic resulted in the Environment,Q presents the panic in the Quality,T presents the panic due to the Throughput,O presents the panic due to loss of Operation,I presents is the catastrophic panic of Immobilization,The corresponding assumed weight “W” for which the probability Pw may follow equation (3).where,P w =1/10 10-w (3)w is a weight factor denoting the severity of the event as related to the frequency and theconsequences.If the accident is categorized as predicted then measures for reducing the impacts and toprevent the occurrence of that accident must be implemented. That is as indicated by equation(4).R EST > R CAL (4)where, R EST is the estimated total frequencies of an event multiplied by the severity ofconsequences, and R CAL is the tabulated standard value at the corresponding associated Risk,60

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTScalculated as shown in table II to be equal on average to 5. This value has been explained in thenext part and Table II and summarized in Figure 5.But if the accident is unpredicted to be non-expected, i.e., remote event, thus equation (5) shallbe applied in this case.R EST < R CAL (5)Fig. 5: Steps involved in the calculations of R CAL6. DISCUSSION AND APPLICATIONS:Table III summarizes some of the cases of the most recently experienced pipeline accidents.The utmost severe case as could be seen is that of Dalian. This accident has been in Dalian,Chinese port. The pipeline had experienced bursting explosion accident on 17 th July 2010, asindicated in Table III. This accident must be treated as if it were expected. That means that the61

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)pipeline integrity should be thoroughly implemented should this type of accident be avoidedwithin RCA implementation. Applying surveillance through good monitoring of the pipelinecan for sure be reflected in the accident prevention.It is to be noted here that applying the frequency per consequence and summing up thefrequencies will yield the probability of the event. Depending on the estimated risk value theseverity of the eventual accident either experienced or expected, or remotely and unexpected,implementing of RCA with advanced monitoring techniques will lead to better preventing therecurrence of the bad event. Thus the downtime and will be reduced enhancing better lifetimesof the concerned pipeline (s).Table I: Typical consequence as well as the associated weight and the probability per eventConsequencePer eventWeight Pw * Severity Probability“W” *of Occurrence1- Loss of lives “LV” 9 10 -1 High Frequent2- Loss of property “LP” 8 10 -2 High Frequent3- Safety “S” 7 10 -3 High Probable4- Environmental “E” 6 10 -4 Moderate Probable5- Quality “Q” 5 10 -5 Moderate Occasional6- Throughput “T” 4 10 -6 Low Occasional7- Operating “O” 3 10 -7 Low Remote8- Reputation “R” 2 10 -8 Low Remote9- Immobilization “I” 1 10 -9 Low Remote(*) W goes up while P goes down6.1 Derivation of Standard Estimated RiskTable II [24] gives the guidance of risk assessment in accordance with ISO 17776 standardsand regulations. The severity as denoted within the five matrix is A (rare), B (repetitive), C(operable), D (repetitive operative) and E (localized repetitive). The increase in probability ofan event to occur is ascending commencing at A, while the highest is at E. The severity of theconsequences can be seen by three grades of the resulted consequences, e.g., none serious,moderate and high damaging. Thus the assessed risk is being either intolerable for events C, Dand E if the severity is 3, 4 and 5 respectively. The second followed category is for reduced62

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSmeasure incorporated risk, e.g., for all events from A to E but the Severity is between 2 up to 5.The third category of the assessed risk is that for all probabilities from A through to E is at aseverity of consequences of poor, e.g., 0 and 1.Table II shows the estimated risk value for the extreme severity at weight parameter of 0.1, theaverage probability is set at 50% and the experienced Consequences are those shown in column“C” of table II. Values of “C” for pipelines have been quoted from references [24]. The totalCritical Estimated Risk as seen in this table is 5.Thus if the actual calculated risk is below this value then the accident is said to be unexpectednevertheless it happened. But if the actual calculated value is above 5, then the event is to beexpected and thus awareness and asset integrity management in pipeline field of practice mustbe thoroughly implemented to find a proper solution to the pipeline problem. Applications ofthe proposed risk assessment compared with those of the ISO 17776 are shown and summed upin Table III and Appendix I.EventTable II: Estimated Average Standard Risk value, R ESTC = Consequences,S = Severity,Causes and ReasonsP avg = AverageProbabilityEstimatedRisk (*)C S P avg [Column 6]C*S*PavgP (**)APoor Design, or wrong material, and /or 36 0.1 0.50 1.800 0.36misuse due to bad operationB Wrong specification 16 0.1 0.50 0.800 0.16C Poor planning 14 0.1 0.50 0.700 0.14D Human error 12 0.1 0.50 0.600 0.12E Bad inspection 10 0.1 0.50 0.500 0.10F Damage to Health 8 0.1 0.50 0.400 0. 08G Damage to Environment 4 0.1 0.50 0.200 0.04∑= 100* R EST = ∑C x ∑S x ∑P** P = [Column 6] /[∑Cx∑Sx∑P]5.0001.0063

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)Table III Applications of the proposed risk assessment as indicated in Figure 5 compared withthe ISO 17776 in major cases of pipelines hazard accidents, R CAL = P * C, Rest== 5.000,estimated at P w 0.1Fig. No. Cause and Reason Sum ofConsequencesCT CT/100P NN T -910 βC RCT*N/9CC R x P WR CAL[P*C]ISO 17776P S RiskFig. I.1 Heavy corrosion A+B+C+D+E 88 0.88 1.318 5 48.89 4.889 6.45 E 5 INFig. I.2 Leak due to corrosion A+B+C+D+E+F 960.96 1.096664.00 6.400 7.02 E 6 INFig. I.3 Bent erosion A+C+E+G 640.64 2.291428.442.8446.52 D 4 INFig. I.4 Poor material A+C+G 540.54 2.884318.001.800 5.19 C 3 INFig. I.5 Stress Corrosion Cracking A+B+C+D+E+G 920.92 1.2026 61.11 6.133 7.37 E 6 INFig. I.6 Crevice Corrosion A+C+E 600.60 2.4773 20.00 2.000 4.95 B 3 TFig. I.7 Leak due to wrong Design A+C+D+E+F+G 740.74 1.8206 49.00 4.933 9.00 E 6 INFig. I.8 Leak due to severe corrosion A+B+C+D+E+F+G 1001.00 1.0007 77.77 7.778 7.78 E 6 INFig. I.9 Miss Operation condition A+C+D+F+G 740.74 1.8205 41.11 4.111 7.84 C 5 ININ = IntolerableT = Tolerable7. CONCLUSIONSFrom the investigated work shown within the text of this paper the following main conclusionscould be drawn:1) Corrosion is the primary epidemic by which pipelines can be deteriorated and resulted indegradation of integrity. Most pipelines corrode on contact with water (and moisture in theair), acids, bases, salts, oils, aggressive metal polishes, and other solid and liquid chemicalscontained within the flow inside the pipeline. All will tend to increase the explosions,bursting and fires if the pipeline will contain flammable material, especially if the pipelinewill carry materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containinggases as the cases in petrochemical and fertilizing factories. Thus the risk for each pipelineshould be defined by RCA and the investigation of the consequences must be defined.2) The simple observation has a major impact in many aspects of accident prevention andcontrol, by applying new monitoring techniques to avoiding the most insidious or localizedforms of bursting within a pipeline. The national income and the economic plans of growthin any country, nevertheless, whether it is developed or still underdeveloped one, may befound to depend and drastically affected by the utility and the efficiency of the pipelineprojects. As the corrosion is known to be the main predominant source of annoyance to all,64

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSthus an International environmental contingency plan taking into consideration the impactsof corrosion rates within the global warming universal phenomenon must be enhanced.3) Root cause analysis shall be applied to investigate previous cases of pipeline accidents,while for new recent cases the approach shall be based on risk which is composed of thefrequency based calculations taken from root cause analysis multiplied by theconsequences of the pipeline accident. The value of the calculated risk then has to becompared by those limits stated by Codes. If it were very high then an alternative solutionmust be applied to reduce as well as to control the results from the pipeline accident. Thishas been furnished as seen in the derivation of risk of pipeline integrity.4) The devised formalized standard risk assessment can be used as a guidance to \\ devisingcounter measures to reduce the resulted hazard. The derived examples show that most ofthose pipeline accidents can be categorized as expected. Therefore the counter action of notrepeating the same accident again, i.e., RCA must be applied and thoroughly implemented.5) The specific tool of QRA (Quantitative Risk Assessment) is subjected to criticism, partlybecause the technique is too academic, and partly because there is insufficient agreementwithin the industry and the HSE on how to use the results of QRA. So, the suggestedguided standard risk assessment has taken all those handicaps into consideration. Theassessment is based on quantitative weight factors that if properly determined then theConsequences in values can be assessed. Also, implementing standard risk values will leadto better decisions and will enhance the implemented guidelines. All will lead to reductionin the recurrence of the event and its impact.6) The management of a pipeline project must be aware to ensure that the relevant statutoryprovisions will (in respect of matters within his control) be complied with in relation to theinstallation and any activity on or in connection with it; established adequate arrangementsfor audit and for the making of reports thereof; also, that all hazards with the potential tocause a major accident have been identified; and that the risks have been evaluated andmeasures have been, or will be, taken to reduce the risks to persons affected by thosehazards to the lowest level that is reasonably practicable in accordance with HSE Act 1992and 1998 Reg. 8.7) Modern risk management approaches applied in pipelines integrity make clear that riskassessment has an important role to play in many risk-related decisions, particularly fordecisions involving uncertainty, deviation from standard practice and risk trade-offs, forwhich pipeline regulations are less appropriate. The decision support framework provides asuitable basis for such decision-making. The HSE tolerability of risk framework showshow risk assessment can contribute to such decisions. As is noted from the nineapplications the proposed model is based on thorough assessments for the consequencesand the risk of the event. The assessments as shown are in matching and in good agreementwith those obtained applying the ISO 17776 model.65

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)8. REFERENCES[1] El-Gammal, M.M. (Sr.), El Naggar, H. H., El-GAMMAL M.M. Jr. (2010) “Life cycle integrity managementapproaches sighted for pipelines for desert use with practical designs and applications,” WORKSHOP “C”, 1 stAsset Integrity Management Egypt, IQPC June[2] EL-GAMMAL, M.M. (1995) “Fitness for Performance Reliability Approach towards Safety of PressureVessels,” AMPT'95, International Conference, Dublin City University, Ireland,[3] EL-GAMMAL, M.M. Sr. El Naggar, H. H., El-GAMMAL M.M. Jr. (2009) “Mitigation approaches tominimize corrosion accidents in pipelines with practical industrial case studies, 4th Annual Middle East PipelineIntegrity Management Summit, Le Meridian, Abu-Dhabi Hotel & Resort, Abu Dhabi, UAE[4] EL-GAMMAL, M.M. (1997) “Fitness for Performance Approach Applications to Welded Joints in Marine &Non-Marine Welded Structures,” 6 th . International Conference on Theoretical and Applied Mechanics, Academyof Science and Technology, Cairo, Egypt, March[5] EL-GAMMAL, M.M.:”Reasons and means of corrosion with proposed methods of protection in offshorestructures,” IQPC- Workshop C- Pipeline Planning and Integrity Management Summit, UAE, Abu-Dhabi, 24February – 27 February 2008[6] EL-GAMMAL, M.M. (2002) “Optimization Technique for Recycling of Engineering Structures Based onProbabilistic Fracture Mechanics and Risk Analysis,” SIAM Optimization Conference, Toronto, Canada,[7] EL-GAMMAL, M.M. (2003) "Fatigue Life Prediction in the Presence of Inherited Defects & Corrosion withMarine Applications," IMRASET Publications, Journal of Marine Design and Operations, Proceedings of MarineEngineering, Society and Technology, No. B3, PP. 3 – 8[8] EL-GAMMAL, M.M. (1975) “A New Method for Estimating the Fatigue Life of Ship Structures,“International Shipbuilding Progress, vol. 22, November, pp. 349-363[9] EL-GAMMAL, M.M. Co-author (1983) “Statistical Evaluation of Fatigue Life of Welded Joints. TheoreticalApproach, “Qualtest-2, Conference, October, Dallas, Texas, USA[10] EL-GAMMAL, M.M. (2007) “Principles and anatomy of reasons of corrosion in marine structures,” The 9 thArab International Conference on Materials Science, Alexandria, Egypt,[11] SMITH, R. (2005) “Asset_integrity, what_to_do_after_an_economic_crisis,” A culture of reliability,http://reliabilityweb.com/i2005,ndex.php/articles/asset_integrity_what_to_do_after_an_economic_crisis[12] EL-GAMMAL, M.M. (2001) "Relationship between Arc Welding Processes and the Evolution of Corrosionin Welded Joints: Reasons and Remedies," 7th International Conference on Production Engineering, Design andControl, Alexandria, Egypt, Vol. III, February, pp. 1847-1862[13] EL-GAMMAL, M.M. (1997) “Scheme of Coating and Surface Treatment for Improving CorrosionResistance with Application to Marine Structures,” Vol. III – Advances in Surface Engineering, EngineeringApplications The Royal Society of Chemistry, London, , ISBN-0-85404-757-3, Paper No. 3-6-2, pp.315- 32466

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTS[14] EL-GAMMAL, M.M. and MENISSI, A. (2010) “Review and study of quality management tools inshipbuilding industry,” Engineering Systems Management Graduate Program, the Second InternationalConference on Engineering Systems Management & Applications,“ Solutions for Regional and GlobalChallenges, American University of Sharjah, UAE. March 30–April 1, and also IEEE, 09 August 2010, ISBN978-1-4244-6520-0,http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5523174%2F5542651%2F05542673.pdf%3Farnumber%3D5542673&authDecision=-203[15] EL-GAMMAL, M.M. Sr. El-NAGGAR, H.H., EL-GAMMAL , M.M. Jr. (2009) “improving processes foreffective corrosion and cracking prevention by implementing advanced protection and repair solutions,”Workshop C, 5 th Annual Asset Integrity Management Summit, 25 th February 2009, LE Meridian, Abu Dhabi,UAE[16] El-GAMMAL,M.M. (2009) “Remedial Maintenance Approach towards Recycling lifetime Applied toMechanical Broken and Damaged Industrial Components, 8TH International Operations, MaintenanceConference, OMAINTEC, Beirut, Lebanon, 6-9- July[17] El-GAMMAL, M.M., SULIMAN, A.M. (2009) “Deep-water marine riser systems lifetime and fractureintegrity prediction and assurance, IMAM 09, Istanbul, Turkey, 12-15 October[18] El-GAMMAL, M.M. (2010) “Discussing surface coating pipeline procedure against corrosion for mechanicaland civil applications,” Workshop E, IQPC 24th February, Sheraton Abu Dhabi Hotel & Resort, UAE[19] El-GAMMAL, M.M. (2010) “Application and Remedial Maintenance Approach towards recycling lifetimeApplied to Mechanical Broken and Damaged Industrial Components.” Paper submitted to OMAINTEC & Hariri2009 Awards: 8 TH International Operations, Maintenance Conference, OMAINTEC, Beirut, Lebanon, 6-9- July[20] El-GAMMAL, M.M. (2010) “Techno-economical remedial maintenance approach towards recycling lifetimewith industrial applications,” Workshop 8, 9 TH International Operations, Maintenance Conference, OMAINTEC,Beirut, Lebanon, 7-10 June[21] EL-GAMMAL, M.M. (2010) “Enhancing the procedure and scheme of passive surface protection forpipelines against corrosion to extend life-cycle and reduce environmental hazards and pollution, “ PAPER, 5 THAnnual Asset Integrity Management Summit, 21 ST February, Sheraton Abu Dhabi Hotel & Resort, UAE[22]ALBERT VAN ROODSELAAR CHEVRON, “RBI of offshore platforms,”http://www.api.org/meetings/proceedings/upload/rbi_of_offshore_platforms_albert_van_roodselaar.pdf[23] DET NORSKE VERITAS (2002) “Marine risk assessment- HSE,” TECHNOLOGY REPORT 2001/063,LONDON CONSULTANCY PALACE HOUSE 3[24] JONES, D. (1999) “Corrosion risk assessment for oil and gas production facilities methodological approach,”CESCOR, http://www.cescor.it/pdf/CRA.pdf[25] NATIONAL SAFETY TRANSPORTATION BOARD (2008) “Explosion, release, and ignition of naturalgas,” Rancho Cordova, California, December, http://www.ntsb.gov/publictn/2010/PAB1001.htm[26]DALIAN PORT PIPELINE EXPLOSION AND FIRE ACCIDENT- 17 TH JULY 2010http://www.boston.com/bigpicture/2010/07/oil_spill_in_dalian_china.html[27]DEEPWATER HORIZON (2010) http://www.offshore-mag.com/index/articledisplay/4402542152/articles/offshore/deep water-horizon/update-on_deepwater2.html67

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)APPENDIX I: Pipeline Failure ExamplesMajor pipeline failures are mainly due to one or more of the following. Gas and oil pipelineshave established an impressive safety record over the years. Some of the causes of failures areidentified in this commentary, other causes are mainly due to one or more of being subjected tomechanical damage resulted from: fatigue cracks or material defects, or fabricated inheriteddefects, e.g., weld cracks, incomplete fusion, improper repair welds, incomplete penetration, orexternal or internal corrosion and or hydrogen blistering. Mechanical damage normally consistsof gouges and dents. They generally are created by excavation or handling equipment duringconstruction.1- Sudden catastrophic failures due to mechanical damage resulted from corrosion degradation,Figures I.1, shows typical deteriorated pipelines in petrochemical industrial factories. The totalestimated consequences is as follows: ∑ C = A+B+C+D+E = 88,Figures I.1: Typical corroded pipelines in petrochemical Factories, expect as disaster [20]2- Leak of flammable oil and gas lead to entire explosion of pipeline at HertfordshireDepot north of London in 2004, Figures I.2. Results from this accident were loss oflives as well as loss of property and can cause fire hazards, ∑ C=A+B+C+D+E+F = 96,Figures I.2: Pipelines carrying flammable materials are the main source of fires [25]68

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTS2- Heavy erosion in elbows and bent connections, may lead to dangerous hazards, FiguresI.3, the resulted consequences are estimated from: ∑ C = A+C+E+G = 64,Figures I.3: Heavy corrosion due to erosion in pipeline bents [21]3- Fatigue cracks in the presence of corrosive agression envieronment that have beenredulted from bad fabrication were the main source for dismantling of offshore pipeline,Figures I.4. The estimated consequences for the offshore pipeline and the exhaust pipe are asfollows: ∑ C = A+C+G = 54,Figures I.4: Dismantling due to fatigue cracks of undersea pipeline and fatiguecracked exhaust pipe [21]5- Stress Corrosion Cracking, is the main source of pipeline failures, Figures I.5, ∑ C =A+B+C+D+E+G= 92,Figures I.5: Wrinkled Pipeline Failed in Compression due to Stress Corrosion Cracking [25]69

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)6- Crevice Corrosion Cracks, is another source of corrosion as shown in, Figures I.6,The estimated consequences is as follows: ∑ C= A+B+C+E = 50,Figures I.6: Typical cases of crevice corrosion cracking in pipelines [21]7- Pipeline Explosions An explosion failure investigation involves determining the rootcause of the explosion. Oxygen and fuel (gasoline, liquefied propane, natural gas, etc.) must bepresent in the proper proportions for an explosion to occur. Also, there must be an event thatignites the oxygen/fuel mixture to create the explosion. RCA provides engineering support ofyour pipeline, b oiler, or petrochemical plant explosion, Figures I.7, [25], ∑ C =A+C+D+E+F+G=84Figures I.7 Left photo for the pipeline Right is some of the habitat resulted damages due to thepipeline explosion, [25]Dalian Port, China,On17 th July 2010, Pipeline accident: Dalian, China [26], two oil pipelines were exploded,sending flames hundreds of feet into the air and burning for over 15 hours, destroying severalstructures - the cause of the explosion is under investigation. The damaged pipes releasedthousands of gallons of oil, which flowed into the nearby harbour and the Yellow Sea. Thetotal amount of oil spilled is still not clear, though China Central Television earlier reported an70

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTSestimate of 1,500 tons (400,000 gallons), as compared to the estimated 94 – 184. Milliongallons in the BP oil spill off the Louisiana coast. The oil slick has now grown to at least 430square kilometers (165 sq. mi), forcing beaches and port facilities to close while governmentworkers and local fishermen work to contain and clean up the spill, Figures I.8, ∑ C=A+B+C+D+E+F+G = 100,Figures I.8.a: Left photo denotes the initial reason for the fire explosion accident and thehazard. Right photo defines panic consequences of the leak accident drowning of two firefighters in the oil slick lakeFigures I-8.b: Resulted Consequences of the fire explosion of Dalian Port, China, 17 th July2010Figures I.8: Part of the damaged pipelines after the fire off Yellow Sea after covering with theslick oil spill [26]9. DEEPWATER HORIZON [27]This tragedian case shall be dealt with in a separate paper due to the importance of applying theRCA into this case. The dilemma starts on 17 th February when all of a sudden the Deep-waterHorizon has been collapsed and foundered unto the water of the ocean. During the accident the71

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)dynamical resulted forces were in excess to the extent that the riser pipeline has been torn off,causing at first white smoke of CO to come out first and then the black oil has been flown offcausing a very large destruction to the echo0systems and badly affecting the environment tillreaching the coast of Florida. The BP has done its best to stop the oil spill but after a period ofalmost 90 days of fighting they have succeeded to kill the reservoir and to stop the oil fromcoming out applying the mud-cement mixture vacuum concept. If they have applied thisconcept from the beginning then there will be no bad resulted consequences either on neitherthe environment nor the exaggerated period of time taken during the trial and error solutions.Thus it was a case of wasting money, effort and great nuisance to all involved in this matterFigures I.9. ∑ C A+C+D+F+G =74,Figures I.9: Case of Deep-water Horizon- The right photo shows the mechanism of the disaster.The white cloud fog came first then followed by the black oil [27].72

AHU J. of Engineering & Applied Sciences 3 (2) : 73-90 (2011)© 2010 ALHOSN UniversityDURABILITY OF CONCRETE STRUCTURES IN THEARABIAN GULF: STATE OF THE ART AND IMPROVEDSCHEMEReem Sabouni ∗Civil Engineering Department, ALHOSN University, P. O. Box: 38722, Abu Dhabi, UAEABSTRACT: The Arabian Gulf region has witnessed an extensive urbanization development during the lastthree decades. Due to its many favorable characteristics concrete, has been the most widely used constructionmaterials associated with this development. Despite the many advantages of reinforced concrete as a constructionmaterial, the service life its structures was found to be significantly below averages standards in the Arabian Gulfregion compared to other parts of the world. Signs of concrete degradation and distress have been witnessed asearly as 5 years in its life time. This is mainly due to the harsh environment of the Arabian Gulf region and evenmore aggravated with the malpractice in the concrete construction which is witnessed in many projects in theregion. The common concrete deterioration mechanisms observed in the Arabian Gulf region are discussed in thispaper, followed by some prevailing durability related practices in the region. This paper concludes with proposinga scheme “Concrete Durability Up Front” that guides the engineer though several steps to reach to one of threeexpected levels of concrete durability depending on the type of durability measures implemented in the project.KEYWORDS: Concrete durability, additives, admixtures, Arabian Gulf, carbonation, chloride penetration,reinforcement, steel corrosion, sulfate attack.1. INTRODUCTIONIn the Arabian Gulf region it concrete deterioration was witnessed very early in thestructure’s life cycle. This is attributed to the harsh environment of the region where statisticaldata showed that temperatures may reach to above 45 o C in some parts and the humidity atcoastal areas may reach up to 100% [1]. What aggravate the durability conditions in theArabian Gulf region are the malpractices associated with the quick fix approaches resultingfrom the fast track construction trends in the region. This resulted in an increase tendency ofusing trial and error approaches among practicing engineers to fix the durability problem. Thislead to a rush in commercially motivated techniques and applications that are not fully testedor standardized, and claim that they give the cure for durability problems of reinforcedconcrete structures [2]. What aggravated the harm is that these techniques were applied withinadequate supervision and considered as alternatives to adhering to the strict standards ofgood practice and workmanship of concreting. Often, durability-enhancing materials andtechniques are applied in the building construction in the Arabian Gulf with inadequatesupervision, lack of quality assurance, and poor quality control leading to low efficiency inresults [3]. This calls for the need of studied schemes to link the durability practices with∗ Corresponding Author. Tel.: +971 4070715E-mail: r.arsabouni@alhosnu.ae___________________________________________* Corresponding Author.Tel.: +971 4070715, E-mail : r.arsabouni@alhosnu.ae173

REEM SABOUNIproper quality control measures. On the other hand, there is a promising rise in the concretedurability awareness in the Arabian Gulf region [4, 5].This paper will begin with discussing the main concrete degradation mechanisms in theArabian Gulf region such as sulfate attack, carbonation, chloride corrosion, and cracking due toenvironmental effects. This discussion will be followed by surveying the prevailing durabilityrelated practices in the region. The paper will be concluded by proposing a scheme to improvethe durability in the Arabian Gulf region.2. MAIN CONCRETE DEGRADATION MECHANISMS IN THE ARABIAN GULFREGIONThe American Concrete Institute defines the concrete durability as the weathering action,chemical attack, abrasion and other degradation processes [6]. Concrete is a synthetic rock thatwill end its life cycle as silica sand, clay and limestone. The more durable the concrete thelonger this process will be delayed [7]. Only the main concrete degradation mechanismsattributed to lack of adequate durability will be considered in this paper. They can becategorized into four classes: Sulfate attack, carbonation, chloride corrosion, and cracking dueto environmental effects. A brief description of each type is given in the following.2.1 Sulfate AttackSulfate attack is a common form of concrete deterioration that occurs when concrete comes incontact with alkali soils or water such as soils when arid conditions exist, in seawater, and inwastewater treatment plants. The most common types of sulfates are sodium, calcium andmagnesium sulfates (which are less common, but more destructive). Potentially all sulfates areharmful due to their chemical reaction, with the hydrated lime, hydrated calcium aluminatesand the cement paste, that produces solid products with larger volumes than the input product[8]. Figure 1 shows an illustrative diagram on the process of sulfate attack.274

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEMEFigure 1: An illustrative diagram on the process of sulfate attack [8].Principal factors that affect the rate and severity of sulfate attack are:1. C 3 A content.2. Permeability of the concrete.3. Ca(OH) 2 content.4. Concentration of sulfates in the waterborne solution.In the coastal areas of the Arabian Gulf, the capillary rise of moisture and frequent floodingfollowed by intense evaporation leaves a heavy crust of salt in the topsoil. When concretestructures are exposed to sulfate solutions, or are placed in sulfate-bearing soils or groundwaters they are subject to sulfate attack deterioration. One of the most common ways ofprotecting against sulfate attack is to reduce the alumina content by limiting the C 3 A inPortland cement. Historically, Type II Portland cement (with C 3 A between 5% and 8%) andType V Portland cement (with C 3 A less than 5%) have been specified for moderate and severesulfate environments, respectively. To minimize damage to concrete due to sulfate attack it is acommon practice in the Arabian Gulf to use Type V cement in the structures in contact with orbelow the ground. Sulfate resistance of the concrete is improved by a reduction in watercementratio and an adequate cement factor, with a low tricalcium aluminate and with properair entrainment. With proper proportioning, and strict quality control, silica fume (microsilica),fly ash and ground slag generally improve the resistance of concrete to sulfate attack, primarilyby reducing the amount of reactive elements (such as calcium) needed for expansive sulfatereactions [3].Studies conducted by Al-Amoudi and Maslehuddin [9] pertinent to sulfate attack in thepresence of chloride indicated some beneficial role of chloride ions on sulfate attack. The375

REEM SABOUNImechanisms are explained based on the contention that in the presence of chloride lesstrisulfate (ettringite) is formed. This reduction in trisulfate is attributed to the fact that itssolubility is increased by chloride ions and that a part of the triculcium aluminate which createsettringite formation is combined as calcium chloro-aluminate. Further, it is believed thattrisulfate crystallizes from the solution when chloride is present, because of the highersolubility of trisulfate in chloride-containing solutions and so it does not cause expansion.Another important finding of this study was the accelerated deterioration of silica fume andblast furnace slag in the magnesium sulfate environment, and the chloride beneficiation wasnot observed in these cements [10].2.2 CarbonationThe reaction between the products of cement hydration and the acidic gases in the atmosphereis namely the carbonation of concrete. The main acidic gas normally available in the air inrelatively low concentrations (0.03%) is (CO 2 ). This concentration is usually higher inindustrial atmospheres were the problem of concrete carbonation arises. Carbonation reducesthe alkalinity of the concrete to a pH value of about 10 and, accordingly, concrete protection ofthe reinforcing steel is lost, which leads to the corrosion of the reinforcing steel. The expansionof the metal reinforcing embedded in the concrete due to this corrosion causes severe damageto the reinforced concrete structure such as spalling and delaminat ion. Figure 2 shows anillustrative diagram on the process of carbonation of reinforced concrete. A good qualityconcrete sufficiently reduces the damage due carbonation because this process becomes veryslow. As well carbonation will not occur when concrete is constantly under water [8].Figure 2: An Illustrative diagram on the process of carbonation of reinforced concrete [8].476

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEMEThe hot and humid weather of the Arabian Gulf is conducive for carbonation of cement, that iswhy it is not uncommon to see sometimes carbonation of concrete to the rebar level. In-situinvestigations conducted by Hussain, et. al., 1994 [11] on a reinforced concrete structure in anindustrial area along the Arabian Gulf, indicated carbonation to a depth of 15 mm on theexterior components, whereas on the interior components it was 3 to 5 mm, after about sixyears. Carbonation of cements is accelerated by chloride and sulfate contamination. Otherstudies [12] reported a greater depth of carbonation in the contaminated cement mortarspecimens than in the corresponding uncontaminated specimens. The increased carbonation inthe contaminated cements is attributed to the changes in the pore structure of cement due to theinclusion of contaminants. This trend of increased carbonation in the contaminated specimenswas also observed in the blended cements. This is of concern, because blended cements usuallyinclude imported costly materials.2.3 Chloride CorrosionThe chloride-induced reinforcement corrosion is a major form of concrete deterioration in theArabian Gulf [13]. The concrete itself is not directly affected by the chloride ions but theycause severe damage to the reinforced concrete structures by the corrosion and expansion ofthe metal reinforcing embedded in the concrete. There are two main sources of chloride ions inthe concrete: penetrated chlorides from the service environment and cast-in chloridescontributed by the mix constituents. Figure 3 shows an illustrative diagram of the chloridepenetration and the associated reinforcing steel corrosion process for cracked and uncrackedreinforced concrete sections. Chlorides occur in either acid soluble or water soluble form. Themost damaging is the water soluble chlorides since they readily become free to attacksurrounding reinforcing steel. If care is not taken in picking the used concrete mix constituentschlorides can be found in reinforced concrete even before the structure is in service. Forinstance if beach sand is used as fine aggregates, having seawater for mixing or in the form ofnatural ingredients found in some aggregates [8]. Table 1, shows the ACI 201.2 R [6]suggested limits for chloride ion in concrete prior to placing concrete into service.Table 1: Limits for chloride ion in concrete prior to placing based on ACI 201.2R [6].Service Condition Chloride to weigh of cement %Prestressed concrete 0.06Conventionally reinforced concrete in a moist0.10environment and exposed to chlorideConventionally reinforced concrete in a moist0.15environment not exposed to chlorideAbove-ground building construction whereno limitconcrete will stay dry577

REEM SABOUNIabFigure 3: An illustrative diagram of the chloride penetration and the associated reinforcingsteel corrosion process: a) Cracked reinforced concrete, b) Uncracked reinforced concrete [8].In substructures, reinforcement corrosion is mostly attributed to the chlorides diffusing fromthe soil and/or ground water. In the superstructure, reinforcement corrosion in majority of thecases is attributed to chloride ions contributed by the mix constituents. Another importantfactor which has accelerated concrete deterioration due to chloride-induced reinforcementcorrosion is the conjoint presence of chloride and sulfate ions in the soil and ground water, orthe mix constituents. The presence of chloride in association with sulfate concentration,increases the corrosion rate, this is of concern for underground structures, where both chlorideand sulfate salts are normally present. For superstructures the effect of high temperatureaggravates the problem of chloride-induced corrosion [10].It is imperative that chloride and sulfate contamination contributed by the mix constituents isminimized. It is a common practice to wash the aggregates to achieve this goal. Other factorsaffecting chloride-induced reinforcement corrosion are the quality of concrete, and the concretecover. Poor quality of the hardened concrete, due to inadequate consolidation, curing,insufficient and non-uniform cover often lead to reinforcement corrosion, even though chloridecontamination is within acceptable limits. The strength, depth of cover and diffusivity of theconcrete all play a role in the prevention of chloride-initiated corrosion of reinforcement.Cracks and construction joints in concrete aggravate the chloride penetration. They allowcorrosive chemicals such as deicing salts to enter the concrete and access embeddedreinforcing steel [14].In the Arabian Gulf environment, Al-Amoudi and Maslehuddin [9] investigated reinforcementcorrosion in the cement paste specimens exposed to chloride, sulfate and chloride plus sulfateenvironments. The results of this study indicated that while the sulfate ions were hardly able to678

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEMEinduce reinforcement corrosion, considerable corrosion activity was observed in the specimensimmersed in the sodium chloride plus sodium sulfate solution. Reinforcement corrosion wasobserved to increase by almost two times when the sulfate concentration in the 15.7% chloridesolution was increased from 0.55 to 2.10%.2.4 Environmental CracksThere are several causes of cracking; but the cracking of concrete structures at early ages is thecause most related to durability. To support the high speed of modern construction trends,high-early strength concrete mixtures are used. Early age cracking is usually associated withthe use of these types of concrete mixes. These cracks may form, by allowing moisture andoxygen to the steel surface, focal points for the other forms of deterioration. Although thesecracks may develop at normal temperature but with hot weather conditions such as that in theArabian Gulf it is of a major concern.There are no clear guidelines in the ACI Manual of Construction Practice on the relationshipbetween crack width and durability of reinforced concrete structures exposed to differentenvironmental conditions. Although ACI 224R-01 [15] report suggests 0.15 and 0.18 mm asmaximum tolerable crack widths at the tensile face of reinforced concrete structures exposed todeicing chemicals or seawater, respectively (see Table 2), the report also contains a disclaimerthat the crack-width values are not a reliable indicator of the expected reinforcement corrosionand concrete deterioration [16].Table 2: Tolerable crack widths in reinforced concrete based on ACI 224R-01 [15].Exposure ConditionTolerable Crack Width (mm)Dry air, protective membrane 0.41Humidity, moist air, soil 0.30De-icing chemicals 0.18Seawater and seawater spray; wetting0.15and dryingWater-retaining structures 0.10For a designer to exercise engineering judgment on the extent of needed crack control, at leastsome understanding of the effect of cracks and microcracks (less than 0.1 mm) on thepermeability of concrete is necessary. A brief summary is presented herein. Generally, at theinterfacial transition zone between the cement mortar and coarse aggregate or reinforcing steel,a higher than average (w/cm) exists, which results in higher porosity, lower strength, and morevulnerability to cracking under stress. Thus, when a structure or a part of the structure issubject to extreme weathering and loading cycles, an extensive network of internalmicrocracks may develop. Under these conditions, the presence of even a few apparentlydisconnected surface cracks of narrow dimensions can pave the way for penetration of harmfulions and gases into the interior of concrete [16].779

REEM SABOUNITo the best of the author’s knowledge, there are no readily available standards that fit the localenvironmental and practice conditions in the Arabian Gulf. ACI Committee 305 guidelines forconcreting under hot weather conditions [17] may not be readily applicable to the Arabian Gulfregion environment. The ACI 305 chart for calculating the rate of evaporation (Figure 4) isbased on a formula that firstly, does not account for the possibility of shrinkage cracks andsecondly, this chart is not valid for ambient temperatures of more than 38 °C. Further, theevaporation rate formulas can be applied only when the surface is completely covered withwater [10].880

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEMEFigure 4: Effect of concrete and air temperatures, relative humidity, and wind speed on the rateof evaporation of surface moisture from concrete (Courtesy of Portland Concrete AssociationJournal 1957) [17].3. COMMONE CONCRETE DEGRADATION PREVENTIVE TECHNIQUES IN THEARABIAN GULF REGIONPreventing concrete degradation should be a main consideration when designing any concretemix or picking materials for reinforced concrete structures especially in the Arabian Gulf dueto its harsh environment. In the mid 80’s Somerville (1986) [18] has proposed the “4Cs ofConcrete Durability” which are:1. Constituents of the concrete mix;2. Cover to the reinforcing steel;3. Compaction; and4. Curing.Several durability enhancing mechanisms have been proposed and tested since then. In generalthe durability of concrete can be enhanced by: proper concrete mix design, providing betterprotection of the concrete and the steel reinforcement. These will be discussed in a conductrelevant to the Arabian Gulf.3.1 Preventive Techniques Related to the Concrete Mix DesignThe durability performance of concrete is mainly influenced by the following mix designparameters: water cementitious materials ratio, cement content and grading and size ofaggregates. Incorporating supplementary cementing materials may be further decreased theconcrete permeability. Some of the most common supplementary cementing materials are: flyash, blast furnace, slag and silicafume [19]. However, in the Arabian Gulf; the use ofsupplementary cementing materials should be considered with caution, due to two reasons.Firstly, the success of the use of the durability enhancing admixtures and additives requiresstrict control on mixing and curing condition, often not guaranteed in the climatic conditionsand the prevailing construction practice of the Arabian Gulf, and secondly, these materials areoften used purely for economic reasons rather than their technical merit.As in other parts of the world, fly ash, blast furnace slag, and silica fume cement have beenused in the Arabian Gulf to improve the denseness of concrete. While blast furnace slagcement has been used in a few structures, fly ash and silica fume, particularly the latter is nowwidely used in new structures and for repair of the old structures.3.2 Preventive Techniques Related to Enhancing the Concrete ProtectionTo improve the service life of reinforced concrete structures its surface can be treated withmaterials such as: penetrants, sealers or coatings. The main function of these treatments is toprevent aggressive species such as moisture and chlorides from reaching to the steelreinforcement. Swamy and Tanikawa [20] studied four different coatings used in the ArabianGulf area for their ability to control chloride penetration and protect the steel from corrosion.981

REEM SABOUNIThis study was carried out by conducting wet-dry or continuous salt spray tests. Based on thetest results a highly elastic acrylic rubber coating was further tested for long term stability. Forconcrete free from chlorides and concrete with up to 1% (of the mortar matrix) sodium chloridecontamination, it was found that the selected rubber coating was able to ensure long termdurability and protect embedded steel by prevent the penetration of air, water and chlorideions.3.3 Preventive Techniques Related to the Protection of Reinforcing Steel3.3.1 Assuring the Quality of Reinforcement Cover:One simple but very important way of maintaining the protection of the reinforcing steel istaking good care of the quality of the reinforcing cover. Meaning, having a cover free ofpockmarks and surface blemishes. A good quality cover is achieved by concentrated effortduring placing the concrete in the cover area, good compaction (without trapped air bubbles orbleed water), high-quality formwork (such as controlled permeability form work) and excellentcuring of the cover zone. Because of harsh climate conditions in the Arabian Gulf curing is ofgreater importance [21].3.3.2 The Use of Inhibitors:Inhibitors are chemical compounds added to the concrete mix to prevent embedded steelcorrosion and should not have adverse effect on the fresh or hardened properties of the concrete[22]. The main inhibitors commonly used in the Arabian Gulf are discussed in the followingparagraphs.3.3.3 Chemical Corrosion InhibitorsCalcium nitrite is the most commonly used chemical corrosion inhibitors. Nitrites are an inhibitorthat enhances corrosion durability by chemically reacting with the ferrous ions to produce a passiveferric oxide protective film that blocks active corrosion centers. The effectiveness of inhibitors inreducing reinforcement corrosion, in the presence of contaminants, such as chloride and sulfate,was evaluated by measuring corrosion potentials and corrosion current density. Most studies arebased on accelerated test rather than long term [10].The effectiveness of selected inhibitors in inhibiting reinforcement corrosion in concretecontaminated with chloride and sulfate salts was studied, and the effectiveness of inhibitors inreducing reinforcement corrosion, in the presence of contaminants, such as chloride andsulfate, was evaluated by measuring corrosion potentials and corrosion current density. Thedata developed in this study indicate that both calcium nitrite and calcium nitrate wereeffective in delaying the initiation of reinforcement corrosion in the concrete specimens madewith sea water, brackish water or unwashed aggregate [10].Mineral Corrosion InhibitorsThe most commonly used mineral corrosion inhibitors in the Arabian Gulf are: Fly ash, SilicaFume, and Ground Granulated Blast Furnace. A brief description of each material with itsadvantages, and disadvantages in the Arabian Gulf is provided in Table 3.1082

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEME3.3.4 Reducing the Vulnerability of the Reinforcing Metals:Besides improving the properties of the concrete to enhance the durability of the reinforcedconcrete structure, reducing the vulnerability of the reinforcing metals will have a favorableeffect on the durability. To achieve that stainless steel can be used as an alternative to ordinaryreinforcing steel [23]. On the other hand, the ordinary steel can be either galvanized or epoxycoated to improve its durability characteristics [21].Fusion bonded epoxy coated (FBEC) bars are used in the Arabian Gulf in concrete structuresexposed to chloride rich environments. They are usually specified for foundations and forreinforced concrete building components about one to two meters above the grade. There aretwo main concerns regarding these types of bars: the first is negative effect of surface damageand holidays on the steel corrosion and the second is the bond strength. Defect free bars shouldbe specified if chloride ions are present in addition to meeting [24] ASTM A 775 [25].Table 3: Mineral corrosion inhibitors commonly used in the Arabian Gulf.Material Advantages Disadvantages CautionsFresh concrete:Fresh concrete:• Improves cohesiveness• plastic shrinkage cracks,• less prone to segregationcare should be exercised to• reduces bleedingprevent early moister lossSilica Fumeor MicrosilicaGroundGranulatedBlastfurnaceSlag(GGBF Slag)Fly AshHardened concrete:• high strength concrete• low permeability, increases resistance tochemical attackFresh concrete:• more workability and placeability• increases time of setting, which isdesirable at higher tempHardened concrete:• improves long term corrosion resistanceof concrete by reducing permeability• improves sulfate resistance• reduces potential expansion ofconcrete due to alkali-silica reactionFresh concrete:• improves plasticity cohesiveness• Reduces bleeding• improves pumpability• improves sulfate resistance• increases time of setting, which isdesirable at higher temperaturesHardened concrete:• low permeability, increases resistance tochemical attack• improves bond of concrete to steel• improves sulfate resistance• increases concrete resistance to chloride• reduces expansion reaction reactivesilica aggregates by consuming alkalisof Portland cement pasteFresh concrete:• plastic shrinkage cracks athigh temperatures• for courser GGBFSbleeding increasesHardened concrete:• greater creep and shrinkagedue to greater volume ofpaste in concrete whencement is substituted byGGBFS on equal massbasisFresh concrete:• longer times of setting mayincrease chances of plasticshrinkage crackingHardened concrete:• in case addition of fly ashincreases the paste volumethe paste volume dryingshrinkage may increasedslightly if water contentremains constant• Ensure that silica fume used is specified tocomply with one of the internationally standards• Trial works must be done to ensure thecompatibility of the silica fume with all theconcrete components, and the proportioning• Proper curing procedures must be followed toobtain the full benefits of the silica fumeconcrete• due to some of the problems with placement ofsilica fume, additional care must be done whenspecifying SFC and the conditions under whichit will be placed• concrete with GGBFS is more susceptible topoor curing conditions• concrete with GGBFS must be kept in propermoisture and temperature conditions during itsearly stages to develop its strength and durabilitypotential• only fly ash with the right chemical compositionand glass content will react sufficiently toachieve the strength and the ongoing pozzolanicreaction to lower long term permeability• only few tested fly ashes would comply tointernational standards1183

REEM SABOUNI4. A PROPOSED SCHEME TO IMPROVE DURABILITY IN THE ARABIAN GULF4.1 The need for a special scheme to improve the concrete durability in the ArabianGulf:The previous parts of the paper concentrated on the factors affecting the concrete durabilitythat are associated with the Arabian Gulf region’s harsh weather. In fact, beside the harshweather the construction practices pursued in the region have a major influence on thedurability of the concrete structures [2]. The concrete industry has a unique situation in theArabian Gulf (that is believed to differ for the rest of the world) due to a combination offactors.The Fast Track Construction Trends: The Arabian Gulf region has witnessed a rapid increasein the construction demand in the last decades. This called for the fast track construction trendsthat are followed nowadays and the increase in the required concrete strength. With the harshweather in the Arabian Gulf these conditions are not usually favorable to durabilityrequirements. To overcome the problem often this is falsely remedied by leaning towards theuse of durability enhancing materials and admixtures [2].4.2 The Rising Sustainability Construction Trends:Several states of the Arabian Gulf region are employing more sustainable construction trendssuch as the Estidama [26] and the Plan Abu Dhabi 2030 [27] that are enforced in the capital ofthe UAE (Abu Dhabi). A number of other states in the region are following the same trends.Both the Estidama and Plan Abu Dhabi 2030 put great emphasis on environmental factors.Recently, the Estidama provisions have been applied as mandatory to the design permitapproval of any building project in Abu Dhabi including private villas. The Esidama ratesbuildings according to its environmental factors into 4 categories with 1,2,3, or 4 Pearls. Oneof the main goals of Plan Abu Dhabi 2030 is to largely reducing the carbon footprint in AbuDhabi City.4.3 Absence of Local Code Provisions: In spite of the ongoing attempts to develop a regionalor national code for the region, there is no national code of practice. A variety of internationalcodes are used for the design and construction of reinforced concrete structures. The choice ofthe code is base on the company’s preference. Some of the widely used international codes arethe US and British codes. Other codes are used –to a lesser extent- by some companies such asthe: Canadian, European, and regional and local Arabic Codes.4.4 Lack of Industrial Related Research: The durability of concrete in the Arabian Gulfresign is the focus of a good volume of research topics (some of which are referred to indifferent parts of this paper). The common shortage of these research topics is the absence of astrong link and coordination with the construction industry. Where, most of these researchesare conducted for academic purposes. It would be beneficial for the construction industry in theArabian Gulf to follow the common practice in North America and Europe of relying onindustrial guided research to help in solving specific arising industrial problems.1284

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEME4.5 No or Little Accountability and Construction Liability: one of the major facts thatinfluence the liability of the construction industry in the Arabian Gulf region is that theconstruction work is either performed by local companies that depend greatly on expatriates, orforeign companies that are allowed to get projects in the region due to the open marketstrategy. This tends to make engineers feel less liable if not committed to high engineeringpractice standards. Another liability issue is the vagueness in the insurance coverage of thedifferent stages of the construction project.4.6 The proposed scheme for concrete durability “Concrete Durability Up Front”:Enhancing concrete durability should Start at an early stage in the project and be part of thestructural design and specification of the project. However, this may be challenging for manyconstruction projects in the Arabian Gulf. Designers are rarely well informed about theproperties of various concrete mixes, and are unable to tell exactly what kind of concrete touse. In addition, sources of materials that the contractors may wish to use rarely adhere tostandard quality control measures. Furthermore structural prescriptive specification for mixesis rarely used.Herein, a scheme to improve the durability of concrete in the Arabian Gulf region is proposed(shown in Figure 5) and its rationale is explained. The scheme’s theme is “Concrete DurabilityUp Front”, where it guides the engineer though several steps to reach to one of three expectedlevels of concrete durability. If no durability measures are required by specifications (and noneare carried out) the scheme expects a concrete deteriorate leading to a high maintenance costfor the structure under consideration. On the other hand, if specifications are required and theminimum specification requirements are met the scheme expects either that the concrete meetsminimum durability standards or that the concrete is highly durable depending on the extradurability measures taken. If extra optional measures are shown to be feasible and will beimplemented, a third party should assure the quality control process. This will mostly lead tohighly durable concrete. The importance of the presence of the third party for quality control isdue to the fact that even if the right durability measures are specified such as adding anadmixture there is no guaranty that this admixture is applied properly with the absence of thisthird party. This is of great importance especially in the Arabian Gulf region where projectsmay not include reliable quality control for onsite concrete mixes or visits to mixing plants forready mix concrete.1385

REEM SABOUNIConcrete DurabilityUp FrontNoRequired byspecificationsYesMeet the minimumrequirements of specsFurther optionalmeasures areconsideredNoYesCost benefit analysisFeasibleNoYesThird Party QualityControlProvidedNoConcrete expected to deteriorateresulting in high maintenance costYesConcrete expected to behighly durableConcrete meets minimumdurability requirementsFigure 5: The proposed scheme to improve durability in the Arabian Gulf “Concrete Durability UpFront”.1486

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEME5. CONCLUSIONSThe durability of reinforced concrete structures is of great importance due to the wide useof this material in the construction projects in the Arabian Gulf region. To reach an acceptablelevel of durability this issue should be thought of in the early design stage of the project. Thispaper addresses the main four concrete degradation mechanisms in the Arabian Gulf region,then surveys the prevailing durability related practices in the region. Finally it concludes withthe proposed scheme to improve concrete durability that has the theme “Concrete DurabilityUp Front”. The proposed scheme guides the engineer though several steps to reach to one ofthree expected levels of durability depending on the type of durability measures taken. If nodurability measures are required by specifications and no special measures for durabilityimprovement are taken the expected level of durability is low and concrete degradation ismore likely to occur resulting in high maintenance cost. If the specifications require durabilitymeasures and those measures are taken, then a concrete meeting the minimum durabilityrequirements is expected. Only with extra durability measures implemented, tied to properquality control and third party involvement, a concrete with high durability and reducedmaintenance cost can be achieved.6. REFERENCES[1] El-Hacha, R., Green, M. F., Wight, G. R., (2010) “Effect of Severe EnvironmentalExposures on CFRP Wrapped Concrete Columns”, Journal of composites forconstruction, ASCE, Volume 14, No. 1, pp 83-93.[2] Sabouni, A. R., (2003), “Evaluation of Durability Enhancing Techniques forStructural Concrete in the UAE”, Proceeding of the 9 th Arab Structural EngineeringConf. (Emerging Technologies in Structural Engineering), Nov. 29-Dec. 1, AbuDhabi, UAE, pp 1217-1228.[3] Sabouni, A. R. Editor, (1999), “Durability Enhancing Materials in Concrete”,American Concrete Institute UAE Chapter, ACI-UAE SP 99-1, USA, October1999, pp 42.[4] Alizadeh, R., Ghods, P., Chini, M., Hoseini, M. and Shekarchi, M., (2006),“Durability Based Design of RC Structures in Persian Gulf Region usingDuraPGulf Model”, Concrete Repair, Rehabilitation and Retrofitting – Alexander(eds.), Taylor & Francis Group, London.[5] Shekarchi, M., Ghods, P., Alizadeh, R., Chini, M., Hoseini, M., (2008),“DuraPGulf, a Local Service Life Model for the Durability of Concrete Structuresin the South of Iran”, The Arabian Journal for Science and Engineering, Volume33, Number 1B, pp. 77-88.[6] ACI 201.2R (2001), “Guide to Durable Concrete”, American Concrete Institute,Farmington Hills, Michigan, USA.1587

REEM SABOUNI[7] Alshamsi, A. M., Sabouni, A. R., Alhosani, K. I., and Bushlaibi, A. H. Editors,(1994), “Reinforced Concrete Materials in Hot Climates”, Proceedings of the FirstInternational Conference on Reinforced Concrete Materials in Hot Climates, UAEUniversity and the American Concrete Institute (ACI), Al-Ain, UAE, April 1994,773 pp.[8] Emmons, P. H., (1993), “Concrete Repair and Maintenance Illustrated, ProblemAnalysis, Repair Strategy, Techniques”, R. S. Means Company, 294 p.[9] Al-Amoudi O. S. B., and Maslehuddin, M., (1993), “The Effect of Chloride andSulfate Ions on Reinforcement Corrosion", Cement and Concrete Research, pp139-146.[10] Maslehuddin, M., (1997), Concrete Durability – The Arabian Gulf Experience,Symposium on Civil Engineering and the Environment, 3 rd -5 th May 1997, KingFahd University, Saudia Arabia, pp 1-12.[11] Hussain, S. E., Paul, I. S. and Ruthaiyea, H. M., (1994), “Evaluation and RepairStrategies for Shallow Foundations”, Proc., 6 th Middle East Corrosion Conference,Bahrain, pp 613-628.[12] Maslehuddin, M.; Shirokoff, J., and Siddiqui, M. A. B., (1996), “Changes in thePhase Composition in OPC and Blended Cement Mortars Due to Carbonation”,Advances in Cement Research, October 1996, pp 167-174.[13] Sabouni, A. R., (1998), “Corrosion, the Prime Cause of Deterioration of ReinforcedConcrete Structures in the UAE” The Engineer Journal, No. 16, UAE University,Al-Ain, UAE, April 1998, pp 2-5.[14] Malhotra, V. M. Editor, (2000), Durability of Concrete, Proceedings of FifthInternational Conference, Barcelona, Spain, CANMET/ACI. 644 pp.[15] ACI 224R (2001), “Control of Cracking in Concrete Structures (ACI 224R-01)”,American Concrete Institute, Farmington Hills, Michigan, USA.[16] Mehta P. K., and Burrows R., (2001), “Building Durable Structures in the 21 stCentury”, Concrete International, American Concrete Institute, vol. 23, No.3,March 2001, pp 57-63.[17] ACI 305R (2001), “Hot Weather Concreting (ACI 305R-01)”, American ConcreteInstitute, Farmington Hills, Michigan, USA.[18] Somerville, G., (1986), “The Design Life of Concrete Structures”, The StructuralEngineer, vol. 64A, No2, February 1986, pp 60-71.[19] Gjorv, O. E., (2009), “Durability Design of Concrete Structures in SevereEnvironments”, Taylor & Francis Group, London, England.[20] Swamy, R. N., and Tanikawa, S., (1993), “An External Surface Coating to ProtectConcrete and Steel From aggressive Environments”, Materials and Structures,Volume 26, pp 465-478[21] Neville, A., (2000), “Good Reinforced Concrete in the Arabian Gulf”, Materialsand structures, Volume 33, pp 655-664.[22] Lafave J, et al., (2002), “Using Mineral and Chemical Durability EnhancingAdmixtures in Structural Concrete”, Concrete International, August 2002, pp 71-78.1688

DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED SCHEME[23] Yunovich, M., and Thomson, N. G., (2003), “Corrosion of Highway Bridges:Economic Impact and Control Methodologies”, Concrete International, AmericanConcrete Institute, vol. 25, No. 1, January 2003, pp 52-57.[24] Eid, O. A., and Marwan, A. D., (2006), “Concrete in Coastal Areas of Hot-AridClimate Zones, Extreme Conditions Accelerated Damage to Reinforced ConcreteStructures”, Concrete International, September 2006, pp 33-38.[25] ASTM A775, (2007), “Standard Specification for Epoxy-Coated Steel ReinforcingBars”, American Society for Testing and Materials, West Conshohocken,Pennsylvania, USA.[26] Abu Dhabi Urban Planning Council, (2008), “ESTIDAMA, Sustainable Buildingsand Communities and Buildings Program for the Emirate of Abu Dhabi”, AbuDhabi, UAE, 133 pp.[27] Abu Dhabi Urban Planning Council, (2010), “Plan Abu Dhabi 2030”, Abu Dhabi,UAE, 185 pp.1789

AHU J. of Engineering & Applied Sciences 3 (2) : 91-100 (2011)© 2010 ALHOSN UniversityCAD AND 3D VISUALIZATION SOFTWARE IN DESIGNEDUCATION:IS ONE PACKAGE ENOUGH?Seif Khiati *Faculty of Engineering and Applied Sciences, ALHOSN University, Po. Box 38772 Abu Dhabi UAEABSTRACT: The present study will discuss the experience of using CAD and 3D software in design programs.Can one or two software packages be sufficient to allow students to visualize and express their ideas or is a largerselection of these packages indispensable? This paper reflects a series of discussions among the faculty andstudents in the departments of architecture at UAE and ALHOSN University. Although the first program inarchitecture in the UAE has existed since 1981, the discussion here focuses only on the last three years of usingCAD and 3D software in the classroom.KEY WORDS: CAD, 3D visualization, education, computer, design.1. INTRODUCTIONSince the introduction of personal computers on campuses in the early Eighties, their role ineducational programs has become central [1]. Today’s computers are both affordable and morepowerful than their modest predecessors. Software has also matured and made things easierincluding in CAD and 3D programs [2]. As computer speed has improved, ease of use andpower of CAD and 3D software has also increased exponentially.Architecture schools are facing the question of how reliant their students should be oncomputer technology [3][4]. In addition, what is the right software to facilitate the students’artistic expression? Administrators and teachers have to make decisions based on the softwarelearning curve, price and power.This paper is not intended to advocate the use of digital technology versus the manual approachin architectural education. I believe that we are passed that type of discussion. It is also worthnoting here that in our department, most classes including design studios are using digitaltechnology with the exception of very few classes.Following the advent of computer technology and CAD in the early Eighties, a number ofarchitects resisted embracing AutoCAD because it was regarded either as a drafting tool or astoo complicated; i.e. an engineering software. Around that time, two packages for architecturecame to the market: ArchiCAD and later Architrion which were both on the Apple Macplatform. These packages presented two different approaches to architecture.ArchiCAD, developed by, and for architects, came to the rescue of those who resistedAutoCAD. Simply put, the program was easy to use, intuitive and built on a set of library_______________________________________1Architecture, Interior design and Urban Design* 2The Corresponding UAE University author: was created Email 1978 s.khiati@alhosnu.ae91

SEIF KHIATIblocks. It provided the tools of a CAD program and allowed the ability to work in a 2Denvironment and view the results in 3D. The user could also edit in 3D and see the changesreflected in plan and elevation. In addition, the cost of the project could be calculated at anytime.Architrion, however, relied on using 3D to generate 2D drawings. The process involvedmodeling the 3D design as far as possible and then extracting 2D information for use in CADdrawing programs.2. GENERAL BACKGROUNDThe Department of Architectural Engineering at the UAE University offers a five yearBachelor program. In the first two years, the students are required to take broad universitycourses (first year) and College of Engineering courses (second year). After this, the studentsspend three years in the Architecture Engineering program.During their first year the students are required to purchase a laptop computer that they will useduring their time at the university. At the moment the system is an Intel 4, running MicrosoftWindows XP. The University encourages active use of computer technology in the classroomand promotes laptop teaching through the use of the Blackboard system.Prior to joining the department, the students take two AutoCAD classes in addition toMicrosoft Office Suite (Word, Excel, PowerPoint, and Access). While in the Department ofArchitecture, the students can take up to two elective courses respectively on Form-Z, 3DStudio Max and/or ArchiCAD. In addition, during their five design studios, the students alsolearn and use at least one of the following: AutoCAD, ArchiCAD, Form-Z, SketchUp or 3DStudio Max.With the exception of AutoCAD, which is officially taught by the university, the rest of thesoftware is left to the faculty to select. Over the years this situation has led to many studentsbeing proficient in more than one software package. In the case where students rely on a singlepackage, this software is ArchiCAD.ALHOSN University offers four year programs in Urban Planning, Architecture, and InteriorDesign, which started five, four and three years ago respectively. In the first year of thebachelor programs above, the students are required to take broad university and College ofEngineering general courses. Afterwards the students spend three years in their respectiveprogram. In general, students take two required courses, one in AutoCAD and another in 3DStudio Max. In addition to the above packages, students also use SketchUp.Mastering software is not based on learning commands alone. Only through heavy use intrying to realize a complete project will the student realize the advantages and limitations of thesoftware he or she is using. A less tangible, but very important aspect is the intuitiveness orelegance of the user interface.92

CAD AND 3D VISUALIZATION SOFTWARE IN DESIGN EDUCATION: IS ONE PACKAGE ENOUGH?3. THE EMERGING STRATEGY: A FLEXIBLE WORKFLOWAllowing faculty to choose and teach software that they feel is appropriate for the task andstudent learning level has led to a positive situation. In many cases a de facto workflow hasevolved with the following characteristics:• SketchUp is ideal for conceptual modeling.• AutoCAD for 2D drafting,• ArchiCAD and/or Revit for 2D and 3D drafting and design development,• Form-Z or 3D Studio Max for advanced 3D modeling ∗ ,• 3D Studio Max for rendering and animation.3.1 Software OverviewThere is a tacit understanding among faculty that the major focus in the program is and shouldbe the architectural design process; i.e. the development from conceptual stage to presentation.Over the years SketchUp has emerged as the program to learn and use first. It is an easy andfast tool with which the student can begin his or her project, and at a later stage, choosebetween AutoCAD and / or ArchiCAD for final drawings and modeling (depending onarchitectural tasks and/or students’ needs).SketchUpSketchUp makes 3D visualization an easy endeavor. It provides the student with tools tocommunicate his/her thoughts in a direct manner. The program is also powerful and easy tolearn. It is the ideal package for First Year architectural students as it helps them understandthe design process. For others it is well suited for starting the design concept. Evenexperienced students use it to design and communicate their ideas quickly.SketchUp allows the student to learn quickly how to put together a 3D mass and to import theresult into a CAD program such as AutoCAD or ArchiCAD. In one of those programs thestudents quickly and easily turn the imported SketchUp sections and mass into plans,elevations and sections. In fact, no major transfer problems have been experienced, and theoverall results of using SketchUp have been very encouraging.AutoCADAutoCAD is a popular CAD program commonly used for engineering and architecturalapplications. For 2D work, the program is probably the best option available. Users like it forits flexibility, user base, customization, compatibility, and support network. The supportedformats of .dwg and .dxf are the standard for moving files between almost all 2D and 3Dapplications. In fact most architectural and construction firms use this software; and many 3rdparty plug-ins are available for it.∗ Or Rhinoceros 3D or Maya for 3D modeling and rendering and animation (for 3D and Maya)93

SEIF KHIATIIn the past, many architectural students felt that AutoCAD was sterile and mechanical; aproduct more tuned to engineers - with add-on packages for architects. Designing in 3D in thepresent version, AutoCAD 2009 has been made easier; but still it is not as smooth andpowerful as in other applications such as ArchiCAD.ArchiCADFor 2D and 3D combination, ArchiCAD is probably a good compromise solution. It is easy touse, and targets architects and other designers. Since its beginning, ArchiCAD has been "byarchitects, for architects" so the interface is more tuned to how architects think and work. Ituses a single building file and object technology concept known as Virtual Building. The userof ArchiCAD generates all required 2D and 3D output from a single file. Users work and editdirectly in both 3D and 2D.Until very recently (Version 11) ArchiCAD had two drawbacks. The first was the look of the2D drawings and the second was that printing was accomplished from a separate program; PlotMaker. Faculties have complained about the quality of ArchiCAD‘s printed 2D outputespecially elevations and sections. This particular point really depends on the student/drafterrather then the program. It is true however for novice students with the default settings that thequality is limited. ArchiCAD do however provide for control of line weights, fills, and textjust as in AutoCAD. The second problem associated with printing from an external providedprogram, a serious one provided extra headaches for the teaching staff. Graphisoft in their lastrelease has solved this issue.RevitAutodesk Revit, while relatively new to the architecture scene in its present incarnation, isactually an evolution of European Building Information software from the mid-nineties. Oneof its strengths is its excellent handling of the .dwg format. Revit is much more likeArchiCAD than AutoCAD, but some of the features are less mature while others are moreadvanced. Revit is relatively sterile windows typical interface. As a marketing strategyAutodesk is selling AutoCAD and Revit bundled together for the price of either of thesepurchased separately.Form-Z ∗Form-Z is the result of the efforts of a group of software developers associated with theArchitectural School at The Ohio State University. Form-Z is a general purpose solid andsurface modeler which has proved to be an effective tool for architects and urban designers.Form-Z is a powerful tool for visualizing any conceivable space or mass. The downside of thispower and flexibility is a cumbersome interface. Form-Z lacks rendering and animationcapabilities.∗ As of 2010, Ohio State University has dropped development of form-Z.94

CAD AND 3D VISUALIZATION SOFTWARE IN DESIGN EDUCATION: IS ONE PACKAGE ENOUGH?3D Studio Max3D Studio Max is a 3D modeler, render and animation program currently owned by AutoDesk.It is used by the film, television and computer game industries. Over the years 3D Max hasappealed widely to architectural visualizers and computer artists. Today a majority ofarchitectural firms world wide use this software for modeling and rendering.With 3D Max, the student has access to powerful tools. 3D Max is well qualified to satisfy allof the user’s needs as a modeler and renderer but it requires a substantial amount of time andeffort to master.In general, however, it would be more productive over time to limit CAD programs to 2D worksince these programs are far less developed and flexible than programs dedicated to 3Dmodeling. CAD programs are rigid due to their tie to its 2D aspect; therefore it becomes verytedious to work in. In fact, based on experience, the suggestion is to stick to 3D programs(SketchUP, 3D Studio Max, etc.) and simply export line drawings such as sections and plans toCAD programs for editing and finalizing.In terms of the workflow mentioned earlier, with the inclusion of Form-Z at one step and 3DStudio Max as another, a good suggestion is to stick with one strong, powerful 3D software asit will allow you to both model and create incredible renderings. Rendering capabilities inprograms such as Rhino and 3D Studio Max can be extended by using plug-ins such as V-ray,flamingo, etc. Workflow then becomes simpler and more fluid. SketchUp if you want quickinitial conceptual development, or immediately start with stronger 3D software to:1- Develop design in 3D,2- Extract sections/plans from model,3- Import into CAD to touch-up and adjust detail drawings,4- Use 3D software to render from a model that is already built,5- Export renderings to Photoshop if needed for further touch-ups,6- Take drawings, renderings and diagrams into your choice of software for presentationpreparation (InDesign, Illustrator, Photoshop).7- The last step is to finalize boards.Of course in the workflow just mentioned, initial stages of conceptual design are not limited to3D software. In fact we must/can include drawings, sketches, and physical sketch model.3.2Workflow Case StudiesThe following are two case studies which demonstrate work done using multiple softwareapplications. Since a picture is worth a thousand words, the captions underneath the followingpictures should be enough to convey some of the students’ ad hoc strategies.95

SEIF KHIATICase study 1Figure 1. AutoCAD drafting overlay ofscanned freehand concept sketch.Figure 4 SketchUp massing study from theimported AutoCAD .dxf file.Figure 2 Revised AutoCAD plan in response toSketchUp massing. Original Plan shown beneath andnew plan super imposed.Figure 5 Final AutoCAD single line site plan.Figure 3 The imported final AutoCAD plan made intodouble line in ArchiCAD. The final project next toexisting on the left.Figure 6 An initial 3D view of ground floorin ArchiCAD.96

CAD AND 3D VISUALIZATION SOFTWARE IN DESIGN EDUCATION: IS ONE PACKAGE ENOUGH?Figure 7 Complex 3D element modeled inForm-Z and brought into ArchiCAD as adxf fileFigure 8 Rendering in ArchiCAD showingthe element imported from Form-Z.Figure 9 Figure 10Figures 9 & 10 Further ArchiCAD perspective renderings.Figure 11 2D site plan graphics generated inArchiCAD.97

SEIF KHIATICase study 2Figure 12 Freehand concept sketch.Figure 13 Evolution of SketchUp massingmodels.Figure 14Figure 15Figures 14 & 15 Views of the ArchiCAD final projects.98

CAD AND 3D VISUALIZATION SOFTWARE IN DESIGN EDUCATION: IS ONE PACKAGE ENOUGH?4. CONCLUSIONS: WHICH IS BETTER, CHOCOLATE OR VANILLA?An individual’s choice of programs all depend on their requirements for use and the specificproject at hand. Learning several CAD and 3D software packages actually provides thestudents with more freedom to visualize and express their ideas. They use the tools that theyfeel more comfortable with. Some students like to experiment, and mastering several programstranslates into different possibilities to achieve a better project. For others, using very few,even only one program, such as ArchiCAD, is everything they need to be able to achieve goodresults.The faculties in architecture, like their counterparts in the professional field, are divided intomainly two groups. One group is quite happy with the use of one package and/or thecombination of two packages. The second group would put more emphasis on the studentslearning a more comprehensive spectrum of applications.Most of the faculty members use and encourage the use of computer technology in theclassroom. The difference is in the degree in which they encourage the student to rely on theuse of computers.Based on experience, no software does it all [5]. For the students, it is important to have accessto several choices; a practical approach would be to use a variety of packages at differentdesign phases. You may ask which software? For AutoCAD users an advance path would beto move to Revit – the function is similar to ArchiCAD. The drawback of Revit for students isa weak rendering capability and an orientation to large multi-user projects. Barring completelynew developments, ArchiCAD will remain the best combination of 2D, 3D and simplerendering capabilities for the student user. Form-Z is certainly the most advanced modeleroriented specifically towards architecture, while 3D Studio Max truly has no limits in regardsto modeling (but is fairly complicated to realize its full potential). SketchUp, despite limitedmodeling power compared to Form-Z, has gained a truly remarkable popularity amongarchitecture students and professionals based on its interface, ease of use, speed and smalllearning curve. For rendering and animation, 3D Studio Max will remain the software ofchoice since its capabilities in these areas are unchallenged by any of the other softwarediscussed.It is interesting to note that the best software for architecture students, ArchiCAD, SketchUpand Form-Z were all developed specifically for architects. In the near future, students ofarchitecture with strengths in programming will be involved in the next software to push thelimitations of present CAD and visualization software.99

SEIF KHIATI5. REFERENCES[1] Andreas Asperl.(2005) How to teach CAD Computer-Aided Design & Applications,Vol. 2, Nos. 1-4, pp 459-468.[2] Tony Longson. Computers in Art an d Design Education — Past, Present and Future.http://old.siggraph.org/education/conferences/GVE99/papers/GVE99.T.Longson.pdf.[3] Julio Bermudez & Kevin Klinger editors (2003). Digital Technology & Architecture -White Paper. Association for Computer Aided Design in Architecture ACADIA:2003. http://www.acadia.org/ACADIA_whitepaper.pdf.[4] Nickolas S. Sapidis & Myung-Soo Kim (2004) Editorial to special issue: CADEducation Computer-Aided Design Design. 36 1429–1430.[5] Jules Moloney Moloney. 3D Game Software and Architectural Education (2001).http://www.ascilite.org.au/conferences/melbourne01/pdf/papers/moloneyj.pdf.ACKNOWLEDGEMENTSThe author wishes to thank all the students who over the years have demonstrated theirexcitement, eagerness to learn, and ingenuity in applying computer technology as it related toarchitecture. Special thanks to the students for their input for this paper and in particular toMrei Al-Zouabi and Hashel S. Allamki for the case studies in this paper; respectively Case #1(design project for Architectural Studio 4) and Case #2 (design project for Architectural Studio2). My apologies to students who provided work examples which I couldn’t include due tospace limitation.My thanks to faculty colleagues at the College of Engineering and Applied Sciences atALHOSN University and at the College of Engineering at UAE University who provided mewith their personal views on the use of CAD and 3D the curriculum. The author also wishesalso to thank Colin Weston and Arch. Mohamed Nazmy for their contributions.100

ALHOSN UNIVERSITY JOURNALOF ENGINEERING AND APPLIED SCIENCESGENERAL INFORMATIONAHU journal of Engineering and Applied Sciencesis a refereed journal, published bi annually byALHOSN University. The aim of of the journalis to emphasize the use of engineering design andanalysis, to publish a high quality research, tostrike a balance between research and applicationand to promote international dialogue andcollaboration. The journal welcomes scholarlysubmissions of original and innovative articlesin all elds of engineering and applied sciences.These include mutually but not exclusively,articles pertaining to the reporting of advances intheory, techniques, methodologies, applications,short communication, review articles and bookreviews.The journal is published bi annually in JuneandDecember each year. Special issues may bepublished from time to time. A guest editor maybe invited to edit a special issue and he/she will beresponsible for the quality of all papers selectedfor publication.Submission of manuscript for publication will beconsidered to imply a tacit understanding that ithas not been previously published is not currentlyconsidered for publication and will not be sent forpublication elsewhere.3. Articles should be served in word format andemailed to the editor with a cover page statingname, email address and where applicable,academic afliation. If a submission includesgraphics and pictures, this should be servedin jpg format and sent as a separate attachmentalong the submission.4. Articles must be doubled spaced and in asingle column format.5. Instructions on the preparation of tables,gures, references and abstracts shouldfollow the IEEE guidelines for publication.at: http://www.ieee.org/publications_standards/publications/authors/authors_journal6. The author of articles will be supplied withone free hard copy of the journal in which his/her paper has appeared by airmail soon afterthe journal is published101129

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