Comparison of collapse-resistant capacities of RC frames with seismic fortification categories B and C

According to the GB 50011—2001'Code for seismic design of buildings',10 typical reinforced concrete(RC) frames were designed with different seismic fortification levels(from 6 to 8.5) and different fortification categories(B and C).The collapse resistances of the frames were evaluated quantitatively with collapse fragility analysis that was based on incremental dynamic analysis(IDA).The collapse resistances of frames with seismic fortification categories B and C were compared.The results show that the collapse resistances of structures should be evaluated in accordance with both the actual seismic resistance and the corresponding design intensity.For frames with seismic fortification level 6 to 7.5,since their actual aseismic resistances are relatively weak,their collapse resistances are insufficient when their seismic fortification categories are upgraded from B to C.So further measures are needed to enhance these structures.