Slenderness Ratio & Compressive Resistance of steel bridge members

[PatrickM111]

Steel compression members for bridges are limited to a slenderness ratio of 120. If I have diagonal truss members that exceed this limit, how do I obtain the compressive resistance of the member, as code formulas must satisfy the limit of the slenderness ratio?

Right now, I'm thinking that buckling effects must then be considered, but there's no guidance in the bridge code (I'm using the Canadian code, but AASHTO would be similar).

Any help is much appreciated!

 

[MiketheEngineer]

You can run lateral bracing across them. Whether a truck will hit them is another question. That becomes a real design problem sometimes. Maybe you can angle them up.

Good luck

 

[PatrickM111]

Actually, it's an existing bridge and we're doing the structural evaluation, so it's a matter of determining the Demand/Capacity ratio. Right now, the problem is trying to figure out the resistance of existing diagonal member built-up of 2 angles not placed back-to-back, but like a C-shape with an open space in the middle.

Thanks.