Steel Design/Check of Structure: Can shell elements provide lateral support to steel beams

[FishTheStructure]

Hello,

I have a 2-D framing layout modeled with area elements to distribute the load to the steel members. When I use the "Steel Design/Check of Structure" function, it calculates the beam's bending moment capacity based on an unsupported compressive flange length equal to the beam length. In reality, the concrete on deck floor is providing continuous lateral support to the compressive flange of the beam and thus the capacities calculated by SAP2000 are much too small.

My question: Is there a way to force the "Steel Design/Check of Structure" function to "see" the shell elements connected to the beam and calculate the beam's bending moment capacity based on continuous support to the compressive flange?

Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein

 

[SteeliestFire55]

You can overwrite the the lateral bracing length as carlaJames above suggested or under Design> Lateral Bracing and specify your own bracing.

Also, try to figure out why SAP2000 didn't consider the shell to be bracing the top flange. Check the 3D extruded view of the frame to see if the shell is connected to the frame at the centroid (default) or at the top of the frame.

It may be worthwhile to ensure that your bottom flange does not go into compression.

 

[structE1973]

It depends... The thicker the shells the more do they prevent the beams from buckling. Some regulations use equivalent spring models to catch this effect arithmetically.

Structural Engineer, PhD
Structural engineering software