Development of DDBD for steel MRFs using inelastic response-based seismic lateral force distribution

Abstract

Direct displacement-based design (DDBD) method is known as an effective performance-based design approach. Although this design method is theoretically stronger than force-based design approach, some previous studies reported the inability of this method to effectively achieve the design performance level. In this study, an improvement of DDBD is proposed for steel moment-resisting frames (MRFs) while the seismic design lateral force distribution is based on the inelastic response of structures. To validate its effectiveness, the steel MRFs with different heights of 4, 8 and 12 stories are designed using this modified DDBD to achieve life safety performance level under seismic hazard having 10 % exceedance probability in 50 years. The nonlinear time history analysis of these frames has been performed under twenty-two earthquake records. The results show the inability of previous DDBD to achieve the desirable performance level whereas the modified DDBD approach has effectively achieved the design performance level. All plastic hinges have been also formed in desirable locations whereas the previous DDBD approach is not quite successful in achieving this goal. The results also show that the elimination of strength-reduction factors from design process of DDBD makes drift ratio and story shear close to target drift limit and design shear. • Inability of current DDBD to achieve design performance level in steel MRFs. • Distribution of seismic lateral force based on inelastic response to improve DDBD. • Location of plastic hinges in steel MRFs designed using DDBD. • Effect of strength-reduction factors on effectiveness of DDBD.