Seismic Design Method for Thin-Walled Steel Frame Structures

Abstract

A seismic design method for thin-walled steel frame structures is proposed in the present paper. The method employs a pushover analysis to investigate the structural nonlinear behavior. A failure criterion accounting for the characteristics of thin-walled steel members and an equivalent single–degree-of-freedom (ESDOF) system are used to estimate the capacity and demand of a structure. The proposed method is a displacement-based design procedure in which not only the global maximum drift but also the residual displacement are evaluated. Limitations of the method due to higher modal effects are also studied, and an applicable range of the ESDOF system is proposed. The method is applied to some examples, and the computed results are compared with those from multi–degree-of-freedom time-history analyses. It is found that the dynamic analysis of the ESDOF model with a simplified bilinear hysteretic model can reliably predict the global maximum drift but cannot provide satisfactory estimations for the residual displacements. Thus, empirical equations relating the residual displacement to the maximum displacement are adopted and found feasible.