when i run a time history analysis, the mass participation factors is more than 100% after mode 7. i used floor diaphragms. is this to cause the issue?
STAAD.Pro CONNECT Edition V22 Update 8.
Can you please attach the STAAD.Pro model?
You had shared a model earlier with this post. Yes, I could see that RIGID DIAPHRAGM commands arecreating problem over there.