Long span composite box girder - balanced cantilever construction

breadmonkey

Hi guys,

I have something in my notes saying that fabricated composite box girders can span up to 300m and are constructed using the balanced cantilever method. Unfortunately, I can't find any examples of this anywhere. Can anyone point me in the right direction?

Thanks

con1982

Hi,

The Millau Viaduct in France uses box girders within the road to span about 320m between piers and they were constructed using a balanced cantilever method. Im not sure if the box girders act compositely with a concrete road deck, but they might. The Discovery Channel have a series called Kings of Construction and you can buy the episode with the Millau Viaduct online.

Conor

breadmonkey wrote: »

Hi guys,

I have something in my notes saying that fabricated composite box girders can span up to 300m and are constructed using the balanced cantilever method. Unfortunately, I can't find any examples of this anywhere. Can anyone point me in the right direction?

Thanks

FesterBeatty

Have a look at this:

http://www.youtube.com/watch?v=bJbd3rvRg7c

The (unloaded) bridge is basically designed to temporarily span as a cantilever until it reaches halfway towards the next support. The next segment cantilevers back to the previous so they meet in the middle (and obviously are connected together) to form a simply supported or continuous beam when in their permanent position and subject to design loads.

Some of them even cantilever all the way to the support (carrying only their self weight - i.e if they carried imposed loads they would collapse if they're note supported at the far end) See below:

http://www.google.ie/imgres?imgurl=http://www.fhwa.dot.gov/bridge/pt/images/pt114.jpg&imgrefurl=http://www.fhwa.dot.gov/bridge/pt/pt01.cfm&usg=__HEii5vih_m8nj_tE48JGHZzVsmE=&h=368&w=528&sz=21&hl=en&start=0&zoom=1&tbnid=6ofYzGnZhs_cXM:&tbnh=111&tbnw=159&ei=quJqTcbWI5SxhQfLydC6DQ&prev=/images%3Fq%3Dbalanced%2Bcantilever%2Bconstruction%2Bmethod%26um%3D1%26hl%3Den%26safe%3Doff%26sa%3DN%26biw%3D1366%26bih%3D667%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=113&vpy=74&dur=138&hovh=187&hovw=269&tx=109&ty=80&oei=quJqTcbWI5SxhQfLydC6DQ&page=1&ndsp=28&ved=1t:429,r:0,s:0