I have a steel framed building with a couple CMU walls in RAM SS. Its a two story building with rigid second floor and pseudo-flexible roof diaphragms, respectively. I have a combination braced frames, moment frames, and CMU walls as my LFRS. My footprint is skewed, but I set the horizontal frames to only take x-direction load and the vertical frames to only take y-direction load for simplicity. If running it with all diaphragms as rigid it works fine, but when I have the roof as pseudo-flexible and I input my % loading to each frame it doesn't work right. My mode shapes are comprised entirely of my CMU walls moving out of plane at the roof diaphragm. How can I fix this?
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