Multi-objective optimal design of SC-BRB for structures subjected to different near-fault earthquake pulses

Abstract

The purpose of this research is to propose a two-objective optimum design technique of self-centering buckling restrained brace (SC-BRB) characteristics based on a multi-objective cuckoo search (MOCS) optimization algorithm for structures subjected to pulse-like near-field seismic excitations. The optimal geometric specifications of shape memory alloy (SMA) and buckling-restrained brace (BRB), including the length of SMA bars, BRB core, area of SMA, and BRB core, are optimized with the aim of simultaneous reduction of the maximum displacement and acceleration of the floors of structures. The numerical analyses are then performed on 3-story and 6-story frames that have been modeled in OpenSees software under pulse-like near-fault earthquakes. The optimized SC-BRB using MOCS considerably reduces the seismic responses of both structures. The SC-BRB also performs better than BRB in severe earthquakes with a shorter fault distance and a larger moment magnitude. Furthermore, SC-BRB has a steady energy dissipation capacity due to more energy absorption in SMA. In terms of maximum top floor displacement and acceleration, the 3-story SC-BRB frame (SC-BRBF) results are reduced the values of 28.3% and 20.1% than the BRB frame (BRBF) for all considered near-fault earthquake pulses, respectively. Moreover, the optimized SC-BRB is considerably capable of reducing the hazards originating from residual drifts and deformations.