The building that I am tasked to design has a steel framing to resist gravity loading. However, it has infill CMU walls acting as shear walls to take the lateral loads. I am only interested in getting the shear distribution to the lateral walls and not interested in their design. What is the best method of modelling these non-load bearing infill CMU shear walls?
Any suggestions is greatly appreciated!
There are two types of solution to this, but there is no setting within the program to specify that a wall is for shear only.
Since we break out the loads cases you can simply run the analysis in Ram Frame for all the loads, but design the wall for only the seismic (or wind) loads, ignoring gravity loads. If you wanted to have self-weight included, that's lumped in with the DL, so you could make the superimposed DL 0 in Modeler and still include DL in the load combinations, but not the Live Loads. This does not really prevent the walls from taking gravity loads, it just ignores them.
The other approach is to frame around the wall with beams that are just a few inches away. Then the wall will only support a tiny tributary area for gravity loads.
The first approach seems a likely choice. I have to model a gravity model to study the girders, that are supporting the roof, supported on columns. Then, study a lateral model, with walls supporting the roof instead of girders, infilled between the columns. The figure below denotes the actual scenario, indicating the section of the wall, supporting the girders.
The Second option of offsetting the walls outside of the perimeter beams would prevent me from framing the walls to the columns. Not sure if this is what I would want!