Seismic analysis and parametric study of SDOF lead-rubber bearing (LRB) isolation systems with recentering shape memory alloy (SMA) bending bars

Abstract

Base isolation has been considered one of aseismic design methodologies based on belief that it is feasible to separate the superstructure from the supporting ground, thereby preserving structural members and their internal contents from damage caused by earthquake motions. Although remarkable progress was achieved in this isolation technique towards the end of the century, a number of catastrophic building failures are still found where earthquake with severe ground motion attacked. In particular, high-rise buildings that have been currently constructed in urban area are very vulnerable when exposed to such impulsive events, and thus large relative displacement occurs at the isolator interface. The obstacles in or in the vicinity of the isolator interface destroy seismic performance. In this study, the innovative isolation systems incorporated with superelastic Shape memory alloy (SMA) bars functioning as seismic restrainers are suggested in order to more effectively maintain structural integrity. The superelastic SMA bending bars supply recentering force to the base isolator that accordingly makes a significant contribution to reducing permanent deformation over entire structure. The base Lead-rubber bearing (LRB) isolators with superelastic SMA bars are considered as inelastic behavior reproduced by component spring elements. The response of the proposed base isolators are compared with those of the conventional LRB isolators. Through the observation of the analysis results, it can be concluded that recentering LRB isolators create the improvement of seismic performance in terms of strength, energy dissipation and recentering effect.