Optimal design of SMA damper for vibration control of connected building under random seismic excitation

Abstract

To alleviate the earthquake induced damages in closely spaced high-rise buildings, linear or non-linear dampers have been frequently employed. Out of different options, the frequently utilized non-linear damper is the yield damper. Yield damper shows good floor displacement control efficiency, but increases peak floor acceleration and leaves large residual deformation at the end of ground motion. Also, it shows degradation in the hysteresis loop; whereas to achieve a good acceleration and displacement control efficiency, it is imperative to have a stable hysteresis loop with negligible residual deformation. In this context, shape memory alloy (SMA) composed damper has been viewed as a potential solution to reduce floor displacement and acceleration, simultaneously. Also, it offers excellent recentering property and good seismic energy dissipation capacity. This research aims to use the above stated superior properties of SMA and investigate the seismic response control efficiency of optimally design SMA damper for connected buildings, and compare with the yield damper. Optimal stochastic responses of connected buildings are estimated under random earthquake, as modeled using the Kanai-Tajimi power spectra. To linearize the non-linear force–displacement behavior of SMA and yield damper, a statistical linearization approach is adopted. The RMS (root mean square) floor acceleration and RMS floor displacement ratios are determined as response outputs for the damper connected buildings. Studies results show that, optimally designed SMA damper is more effective in reducing acceleration of stiff building and displacement of the flexible building than the yield damper. Compared to the yield damper, SMA damper reduces the RMS acceleration ratios by 15 % for the flexible building and 35 % for the stiff building; and RMS displacement by 20 % for the flexible building and 0.5 % for the stiff building. Overall, SMA damper provide much better seismic response control efficiency for connected buildings than yield damper.