Performance-based assessment and design of FRP-based high damping rubber bearing incorporated with shape memory alloy wires

Abstract

This study deals with two new generation smart high damping rubber bearings (HDRBs) incorporated with shape memory alloy (SMA) wires. Due to the superelastic effect and the re-centering capability of SMAs, the residual deformation in SMA-based elastomeric isolators is reduced. Two different configurations of SMA wires incorporated in rubber bearings are compared by changing the aspect ratio of base isolator, the type of SMA, the thickness of wires, and the pre-strain in wires where the isolator is subjected to a vertical pressure and unidirectional cyclic lateral displacement. A performance-based design flowchart is also provided along with a design example for determining the pre-strain and the radius of cross section of wires in the SMA wire-based rubber bearings. Results demonstrated that using ferrous SMA wires (FeNCATB) with 13.5% superelastic strain in the cross configuration leads to the best performance since the strain induced in wires is significantly decreased. Seismic performance evaluation of a three-span continuous bridge isolated by smart HDRBs shows that using SMA wires with cross configuration leads to the highest energy dissipation during earthquake. However, implementing SMA wires into HDRBs has negligible effect and in some cases no effect on the pier displacement and peak deck acceleration. It was also observed that neither of the HDRBs nor the SMA-HDRBs experienced any residual deformations when they were subjected to three different ground motions scaled by Vancouver design response spectrum.