Shaking table tests on seismic behaviors of a single-layer spherical lattice shell with shape memory alloy-controlled friction pendulum bearings

Abstract

An innovative seismic isolation device incorporating a friction pendulum bearing (FPB) and vertically aligned shape memory alloy (SMA) strands is proposed for the seismic control of spherical lattice shells located in strong-earthquake regions. To validate the effectiveness of the proposed SMA-FPBs experimentally, a 1/10-scale single-layer spherical lattice shell test structure and a set of isolators were designed and fabricated. A shaking table was used to apply various three-dimensional seismic excitations to test structures equipped with and without different isolation bearings (SMA-FPBs or bare FPBs). Significant seismic behavior enhancements were observed when such isolation systems were used. However, bare FPBs cannot accommodate excessive displacements induced by high seismic intensities owing to their lack of adaptive control. In contrast, SMA-FPBs exhibited satisfactory control performance in terms of the peak and residual bearing displacements under fortification and rare seismic actions, and the adaptive properties of the SMA-FPBs protected the isolators from disassembly owing to excessive sliding displacements under extremely rare earthquakes, even though their re-centering abilities decreased slightly because of the failure of several SMA wires. Finally, the larger number of SMA wires in an SMA-FPB enhanced its restraining capacity against peak bearing displacement rather than improving the seismic responses of structural nodes and members.