Performance-based design optimization of steel moment frames using capacity controlled search algorithm: a comparison with force-based design approach

The capacity controlled search (CCS) method, which is a recently developed design-driven search algorithm, is implemented for performance-based design optimization (PBDO) of steel moment frames. It is shown that the CCS method is very suitable for PBDO problems since it can locate the optimum solution using a reasonable computational effort unlike metaheuristic search approaches, which often require thousands of structural analyses before converging to a near-optimum solution. Considering the fact that performance-based design (PBD) is a recently emerging design methodology, its comparison with the traditional force-based design (FBD) approach is also carried out extensively in this study. Accordingly, the optimum designs of the investigated steel frames produced according to both design methodologies using the CCS method are compared in terms of structural weight and seismic performance. Unlike most of the previous studies, not only inter-story drifts but also hinge rotation limits are considered as seismic performance criterion during PBDO process of steel moment frames. The numerical applications are presented using three ordinary moment resisting steel frames. It is shown that although the FBD methodology usually leads to heavier designs with respect to the PBD methodology, the optimum designs produced according to the former might fail to satisfy seismic performance requirements.