"**WARNING: IF THIS UBC/IBC ANALYSIS HAS TENSION/COMPRESSION OR REPEAT LOAD OR RE-ANALYSIS OR SELECT OPTIMIZE, THEN EACH UBC/IBC CASE SHOULD BE FOLLOWED BY PERFORM ANALYSIS & CHANGE."
I did not understand anything from that warning but it contd to analize the structure. I wanna ask you that is my seismic analysis correct?
P.s: I entered 0.8s period values on purpose. And i know my modal analysis is wrong.
You can find answers to your first question on this topic.
You should check your material properties for concrete that you have used in your model.