Optimal seismic‐resistant design of a planar steel frame

Abstract

AbstractThis paper illustrates the design of a four‐storey, three‐bay, moment‐resisting, planar steel frame. Non‐linear step‐by‐step integration is used as the analysis technique within the design process itself rather than as a check at the end of the design process.The method of design directly quantifies the accepted seismic‐resistant design philosophy that a properly designed structure: (1) resists moderate ground motion without structural damage, and (2) resists severe ground motion without collapse. Actual ground motion accelerograms are selected and scaled to levels representing moderate and severe ground motions. Constraints quantifying structural damage and limited non‐structural damage are constructed for the case of moderate ground motion, along with constraints quantifying collapse and limited structural damage for the case of severe ground motion. In addition serviceability constraints are imposed on structural behaviour under gravity loads only. Objective functions include the minimization of structural volume as well as the minimization of response quantities such as storey drifts and inelastically dissipated energy.A sophisticated optimization algorithm is utilized to solve the resulting mathematical programming problem. Comparative results concerning the computational phase as well as performance of both preliminary and final designs are presented. The practicality and reliability of the design method are assessed.