Modelling a steel top flange and concrete deck in FEA

[VoyageofDiscovery]

Hi,

I am modelling a continuous composite box girder bridge in FE. So far I have been neglecting the top flange under the deck and haunch, while only accounting for it by adding its weight at deck level. I know this can't be right! Do you assume a cracked concrete deck section over the pier, if so for what length?

What do you do?

VOD

 

[DoubleGeek]

It really depends on what you're trying to model, but if it's going to be a real bridge, then it won't truly be "continuous". Typically for a bridge structure, you're looking for load deflections or critical stress points due to external loads. If so, try building a half-span and constrain the pier side by applying appropriate forces, but only apply moments (in the form of lateral forces) at the half-span point. This will allow you to obtain static equilibrium but see deck deflections due to forces applied at any point on the span. Also note that bridge ends are usually pinned at one end and allowed to float horizontally at the other, so you'll have to pick which part of the span you want to model.

Forgive me if I've oversimplified your problem.