Optimization of linear seismic isolation parameters via crow search algorithm

Abstract

In this study, isolation parameters of a seismic isolated structure were optimized via crow search algorithm (CSA). A shear frame model was generated with a base isolation system. The aim is to obtain isolation system parameters that result the minimum roof acceleration without exceeding the isolator displacement limits. The Matlab program was used for optimization operations and the SAP2000 program was used for structural analysis. The open application-programming interface (OAPI) was employed for the two programs to work together. Time history analyses were conducted using recorded near- and far-fault earthquake ground motions. Within the content of the study, linear isolator system parameters, which are the isolator period and damping ratio, were optimized through the linear time history analyses results by achieving the predefined aim. The analyses were performed for various isolation displacement limits and damping ratio ranges. The optimum results were determined at the range of various displacement limits and damping ratios by attaining the specified upper limits for displacement in all cases. Since higher damping ratios cause increased floor accelerations, optimum isolation parameters were achieved generally at the intermediate damping ratios well below the upper limits. Therefore, optimum isolation parameters are crucial for obtaining minimum floor accelerations. The verification of the optimum isolator parameters, which are achieved by the crow search algorithm employed, was made by comparing them with the results of a previous study.