Improved seismic design method for steel moment frames

Force-based and displacement-based methods are two conventional approaches for the seismic design of structures. Recently, the advantages and disadvantages of these methods have activated the researchers to combine them and to introduce the hybrid force–displacement (HFD) seismic design methods. In this paper, a new method named “modified seismic coefficient” for steel moment frames (MRFs) is presented. For this purpose, the seismic behavior factor and response spectrum of the structure are determined based on actual structural response and also the fundamental period of the structure. For practical examples, at first, a series of three (3, 6, and 9-story) MRFs is designed based on the proposed method and a classic HFD method, and then, their seismic responses are evaluated using nonlinear time-history analyses. For satisfying life safety (LS) performance level, it is observed that the proposed method reduces structural weight as 27, 22, and 24% for 3, 6, and 9-story frames, respectively. © 2020, Springer Nature Switzerland AG.