Building analysis for inelastic earthquake design of regular moment frames and dual systems addressing moment redistribution

A secant stiffness analysis method for the inelastic earthquake design of building structures was developed. In the proposed method, inelastic design forces and deformations of individual members were directly determined by using linear analysis for secant stiffness. By considering a desirable plastic mechanism for a structure, members are classified into elastic or inelastic members. For inelastic members, secant stiffness is used. The magnitude of the secant stiffness is determined by considering the target ductility of the structure. Particularly, for moment redistribution, structures are modeled with beam–column elements having non-rigid end connections (NREC element). The redistributed moments and plastic rotations of individual members can be evaluated from the results of secant stiffness analysis. The proposed method was applied to regular moment frames and dual systems. The design results were compared with the results of nonlinear analysis.