GA-based optimum design of a shape memory alloy device for seismic response mitigation

Abstract

Damping systems discussed in this work are optimized so that a three-story steel frame structure and its SMA bracing system minimize response metrics due to a customtailored earthquake excitation. Multiple-objective numerical optimization that simultaneously minimizes displacements and accelerations of the structure is carried out with a genetic algorithm (GA) in order to optimize SMA bracing elements within the structure. After design of an optimal SMA damping system is complete, full-scale experimental shake table tests are conducted on a large-scale steel frame that is equipped with the optimal SMA devices. A fuzzy inference system is developed from data collected during the testing to simulate the dynamic material response of the SMA bracing subcomponents. Finally, nonlinear analyses of a three-story braced frame are carried out to evaluate the performance of comparable SMA and commonly-used steel braces under dynamic loading conditions and to assess effectiveness of GA-optimized SMA bracing design as compared to alternative designs of SMA braces. It is shown that peak displacement of a structure can be reduced without causing significant acceleration response amplification through a judicious selection of physical characteristics of the SMA devices. Also, SMA devices provide a re-centering mechanism for the structure to return to its original position after a seismic event.

Performance assessment of buildings isolated by shape-memory-alloy rubber bearing: Comparison with elastomeric bearing under near-fault earthquakes

“…SMA‐based dampers have been employed for seismic vibration control of cable‐stayed bridges . Parametric studies have also been conducted to propose a range of optimal parameters in such system. The optimal range of design variables is also suggested for the SMA‐based seismic isolation by Ozbulut and his co‐workers by adopting a framework based on genetic algorithm .…”

Nonlinear dynamics of shape memory alloy oscillators in tuning structural vibration frequencies

“…Furthermore, a recently developed hybrid optimization methodology, combining the local and global search algorithms, has proved to be a useful tool in studying the dynamics of phase combinations in SMA samples [74]. A similar idea based on the genetic algorithm was recently pursuit in [75] specifically in the context of damping systems and seismic response mitigation.…”

Research and development of an innovative self‐centering energy dissipation brace

“…It demonstrated that the BRB component provided energy dissipation and the SMA rods provided the self‐centering and additional energy dissipation. Ozbulut et al investigated the performance of super‐elastic Ni–Ti SMAs for the seismic applications through numerical and large‐scale experiment. SMA damping devices were installed to a steel frame structure, and the residual displacements of the SMA‐braced frame were significantly reduced after the excitation was moved.…”