Re: RISLI BUILDING ANALYSIS PROBLEM IN STEEL BUILDING Hello ; There is no risky building analysis in the program for steel structures. For the reinforced concrete section, there must be a rigid diaphragm on each floor. Therefore, define a slab, defining a reinforced concrete material with a unit volume weight of 0 for the slab material will eliminate its effect on the system, choose mode combination for the dynamic calculation method from the analysis settings, and fully rigid diaphragm must be selected from the analysis settings. For reinforced concrete flooring material, you can use the add new material command from the building wood materials section. Make sure to set the unit volume weight of the material to 0. Good work.