The current study evaluates the seismic vulnerability of the Indian code, confirming RC frame buildings located in the most severe seismic Zone V of India using fragility analysis.

Two-, four-, eight-, and twelve-storey RC frame buildings are designed based on the stiffness of the uncracked section as per IS 1893:2002 and the effective section as per IS 1893:2016, respectively, using relevant Indian codes. The seismic vulnerability of all designed RC frames is investigated by carrying out a performance assessment using pushover analysis followed by fragility evaluation. The design of RC frame building based on elastic stiffness of effective section in linear seismic analysis indirectly enhances the strong column to weak beam (SCWB) ratio, and noticeable improvement in the failure mechanism and lateral responses of RC moment-resisting frame is observed.

The results of fragility analysis suggest that an RC frame designed based on the full elastic stiffness of uncracked section during linear analysis had more seismic fragility than a frame designed based on the elastic stiffness of the effective section. The estimated values of the response reduction factor (R) using the idealised capacity curve suggest that the Indian seismic code overrates the R factor for the RC frame designed based on the elastic stiffness of the uncracked section, which leads to the potentially risky estimation of the design seismic base shear on the lower side.

The collapse probability of the RC frame designed using effective section as per revised seismic code is approximately 57 per cent less than the frame designed using gross section as per older seismic code.