Seismic Assessment of Vertically Irregular RC Buildings Designed Using DDBD and FBD Approaches

For structures with frames made of reinforced concrete, the force-based design (FBD) method's drawbacks have been solved by the direct-displacement-based design (DDBD) technique, a significant achievement in the structural field. The current work used numerical analysis to investigate the inelastic behaviour of structures made with FBD and DDBD. It takes into consideration RC frame buildings with six and thirteen stories as examples of mid-rise and high-rise RC structures. Non-linear dynamic evaluation is conducted to assess the effectiveness of both approaches in developing the selected RC structures. As a performance criterion, the life safety limit (2% target drift: FEMA-356) is taken into consideration. The analyses of selected irregular frames are carried out using ETABS 2016 software. The important factors evaluated are base shear ratio, displacement profiles and inter-story drift ratio (ISDR). Based on the obtained results it is concluded that the mid-rise and high-rise RC irregular structures constructed using the FBD method have mean drift ratios exceeding 25% higher than the desired drift. Whereas, RC irregular structures constructed using the DDBD method have satisfying mean drift ratios of 40% to target drift. Further, research highlights the need of a DDBD procedure in the Indian seismic scenario to assess the building’s seismic risk.