Brdge girders temporary bracing. 1

[bbrue]

Hello,

I need to design temporary bracing between the facia and first interior girders (plate girders) for a highway bridge. The design engineer has crossframes spaced between 25 and 31 feet and calls for temporary bracing midway between crossframs to be designed by the GC/fabricator. The temporary bracing is to prevent buckling prior to and during the pouring of the composite deck. The deck overhang is 3'6" beyond the facia girder.


I am having trouble finding guidelines to design for this temproary situation. Do I need to design for construction loading only? Any reccomendations or reference manuals that might apply to this situation.

 

[kylesito]

I think the reason you are having trouble finding guidelines is that there probably isn't any to be found...this is a case where you have to rely on engineering judgment to make the right decision.

I think construction loads is adequate but think through all possibilities for developing your load cases...for instance, the weight of wet concrete, the weight of any finishing equipment, the weight of any pouring equipment/trolley. You may also need to look at environmental conditions...for instance, depending on where you are located is there a chance a snow/ice storm will hit before the composite beam can reach capacity.

Just think through the construction process and design your falsework to accomodate it.

When in doubt, make it stout.




PE, SE
Eastern United States

"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi

 

[MiketheEngineer]

Don't forget the weight of workers - sometimes significant.

 

[bridgebuster]

Kansas DOT has a program called TAEG - Torsional Analysis of Exterior Girders - it's a free download. I've found it to be helpful. It's written for the situation you have. Also, it beats doing a god-awful torsional analysis by hand.

http://kart.ksdot.org/