Stacked Beams

Hi,

I am trying to design structural modification to a braced frame. Existing is a concentrically braced frame which needs to be modified to eccentrically braced frame. One brace connected to the spandrel beam will stay whereas the other will be moved half way up the column height. Imbalance of moment requires adding additional beam stacked underneath the existing. In RISA 3D, how would one make sure the two beams are stitched together? I normally use arbitrary members connecting center lines of two members, however here if I remove the arbitrary members both beams get over stressed.

Thanks

Thanks,

FEM4Structures

 

[jayrod12]

If you have RISA-section you could build your new section in that and import it into RISA-3D. It works pretty slick

 

[JoshPlumSE]

In the Modeling Tips section of the help file there are a couple of similar (though not identical) modeling situations described. Modeling Composite Behavior and Modeling One Member Over Another.

The sub-topic on composite behavior talks about making sure a concrete slab and steel beam are "stitched together" continously along the length of the beam. Same sort of situation as you except you are stitching two members together.

Jarrod's suggestion works as well. You can always model the member as a single member. Just make sure you've got the proper section properties calculated.