VSL's innovations Dampers on test Penny's Bay in HK
VSL's innovations Dampers on test Penny's Bay in HK
VSL's innovations Dampers on test Penny's Bay in HK
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ti<strong>on</strong><br />
Competitive<br />
post-tensi<strong>on</strong>ed<br />
steel truss form<br />
Purpose<br />
VSL <strong>in</strong> Chile has developed<br />
a footbridge design for<br />
complete c<strong>on</strong>structi<strong>on</strong><br />
soluti<strong>on</strong>s <strong>in</strong> c<strong>on</strong>crete that uses<br />
<strong>on</strong>e c<strong>on</strong>t<strong>in</strong>uous structure<br />
across all spans. A formwork<br />
system was needed.<br />
Descripti<strong>on</strong><br />
The c<strong>on</strong>structi<strong>on</strong> of the forms<br />
starts with the assembly of<br />
the modules <strong>on</strong> the floor.<br />
After that the various<br />
modules are stressed<br />
together with <strong>in</strong>dividual<br />
strands. All the modules are<br />
lifted <strong>in</strong>to positi<strong>on</strong> as <strong>on</strong>e<br />
unit. The post-tensi<strong>on</strong><strong>in</strong>g <strong>in</strong><br />
the form is released after<br />
completi<strong>on</strong> of the post-<br />
VSL modular form traveller<br />
Purpose<br />
This formwork system for c<strong>on</strong>structi<strong>on</strong> of cast <strong>in</strong>-situ bridges us<strong>in</strong>g<br />
the FC method was developed for easy reuse from project to project,<br />
to m<strong>in</strong>imise <strong>in</strong>vestment <strong>in</strong> new steel and equipment and to reduce<br />
redesign costs for <strong>in</strong>dividual projects.<br />
Descripti<strong>on</strong><br />
An overhead system was selected due to its more favourable<br />
<strong>in</strong>troducti<strong>on</strong> of support reacti<strong>on</strong>s <strong>in</strong>to the deck, its reduced selfweight<br />
and its possible use for cross-secti<strong>on</strong>s with more than two<br />
webs. VSL’s modular traveller features:<br />
• use of grade 40 steel with no need for SHS;<br />
• a traveller launch<strong>in</strong>g system which provides l<strong>on</strong>gitud<strong>in</strong>al fixity for<br />
both uphill and downhill launch<strong>in</strong>g, through the use of doubleact<strong>in</strong>g<br />
l<strong>on</strong>g-stroke jacks c<strong>on</strong>nected by p<strong>in</strong>s to the rail beam;<br />
• rear tie-down of the traveller with 2 x 4 stress bars, all of them<br />
located outside of the webs.<br />
Performance<br />
The ma<strong>in</strong> performance characteristics are:<br />
• bridge alignment - gradient up to 5%,<br />
horiz<strong>on</strong>tal curve greater than 500 m,<br />
superelevati<strong>on</strong> up to 5%;<br />
• segment geometry - segment length<br />
up to 5m, segment weight up to 180t<br />
(for a s<strong>in</strong>gle box; higher for multiple<br />
boxes), s<strong>in</strong>gle or multiple cell box<br />
girder, vertical or <strong>in</strong>cl<strong>in</strong>ed webs;<br />
• pier table length - m<strong>in</strong>imum length<br />
7.2m, m<strong>in</strong>imum length for<br />
simultaneous <strong>in</strong>stallati<strong>on</strong> of a pair<br />
of travellers 8.2m. ■<br />
tensi<strong>on</strong><strong>in</strong>g of the footbridge. Each<br />
module is then removed separately.<br />
Advantages<br />
•Pours are completed without<br />
<strong>in</strong>terrupt<strong>in</strong>g the traffic; vertical and<br />
horiz<strong>on</strong>tal clearances are<br />
ma<strong>in</strong>ta<strong>in</strong>ed dur<strong>in</strong>g c<strong>on</strong>structi<strong>on</strong>.<br />
• The system is easy to mount and<br />
dismount.<br />
• Use of post-tensi<strong>on</strong><strong>in</strong>g reduces the<br />
force <strong>in</strong> the bolts <strong>in</strong> each<br />
c<strong>on</strong>necti<strong>on</strong>, and allows c<strong>on</strong>trol of<br />
vertical deformati<strong>on</strong>. ■<br />
N E W S N ° 1 • 2 0 0 4<br />
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