Seismic layout optimization of steel braced frames by an improved dolphin echolocation algorithm

The present paper tackles the problem of seismic performance-based layout optimization of steel braced frames subject to earthquake loading. Design variables of the optimization problem include the cross-sections of beams, columns, X-bracings and the placement of the bracings in the frame. To check the ultimate limit-state constraints during the optimization process, the structural responses are computed at the performance levels by conducting nonlinear static pushover analysis. In order to implement the optimization task an improved dolphin echolocation meta-heuristic algorithm is proposed. In dolphin echolocation algorithm, the echolocation behavior of dolphins is simulated to search the design space of the optimization problem. To illustrate the efficiency of the proposed methodology, five numerical examples are presented. The numerical results demonstrate the superiority of the proposed meta-heuristic over its standard version. Furthermore, it is observed that the performance-based layout optimization process finds structural configurations which are about 10 % lighter than those of obtained by the pure sizing optimization.