Multi‐stage superelastic variable stiffness pendulum isolation system for seismic response control of bridges under near‐fault earthquakes

Abstract

To improve the resilient capability of bridges, a novel multi-stage superelastic variable stiffness pendulum isolator (SVSPI) is developed by incorporating superelastic shape memory alloy (SMA) with the multi-stage variable stiffness pendulum isolator (VSPI), which featured with the favorable adaptability under service conditions and near-fault excitations. Based on OpenSees platform, the numerical model for novel multi-stage superelastic variable stiffness pendulum isolator is created. A fractional factor based design method is suggested for parameter optimization of the multi-stage superelastic variable stiffness pendulum isolator. The example bridges with the novel isolators are designed to conduct the seismic mitigation investigation under near-fault earthquakes. The effectiveness of the novel superelastic multi-stage variable stiffness pendulum isolator and suggested design method is further discussed by case study. Results show that the novel multi-stage superelastic variable stiffness pendulum isolator designed by the proposed fractional factor based design method can perform the dual control of the isolator residual displacement, girder displacement, and base forces in piers for bridges. The effectiveness of the multi-stage superelastic variable stiffness pendulum isolator with the optimal parameters is demonstrated by case study. The technical achievements can provide reliable basis for structural resilience enhancement and potential structural applications.

Superelastic Conical Friction Pendulum Isolator for Seismic Isolation of Bridges under Near-Fault Ground Motions

“…Due to the symmetrical nature of the thermal deformation, the movements induced in a spherical surface can lift up the girder, negatively impacting the serviceability of the bridges underservice loadings (such as braking force). Also, the friction pendulum with constant curvature may inevitably introduce a constant isolation period to the seismically isolated structures [25][26][27]. As a result, resonance may be triggered when the isolation system is subjected to strong ground motions dominated by long-period components, such as near-fault earthquakes [26][27][28].…”

“…Also, the friction pendulum with constant curvature may inevitably introduce a constant isolation period to the seismically isolated structures [25][26][27]. As a result, resonance may be triggered when the isolation system is subjected to strong ground motions dominated by long-period components, such as near-fault earthquakes [26][27][28].…”

“…Several investigations have been focused on improving the passive adaptability of the traditional friction pendulum [25][26][27][28][29][30][31]. One example is the variable curvature friction pendulum, which can effectively improve the performance of structures [27,31,32].…”

“…Several investigations have been focused on improving the passive adaptability of the traditional friction pendulum [25][26][27][28][29][30][31]. One example is the variable curvature friction pendulum, which can effectively improve the performance of structures [27,31,32]. In particular, the conical friction pendulum with an inclined plane tangent to the spherical surface can effectively control the maximum seismic force [30][31][32].…”

Design Optimization of a Hybrid Vibration Control System for Buildings

“…Shape memory alloy (SMA)-based friction pendulum bearings (FPBs) were proposed in order to control a three-span continuous isolated bridge [14]. A multi-stage super-elastic variable stiffness pendulum isolator (SVSPI) was generated by hybridizing of super-elastic shape memory alloy (SMA) and the multi-stage variable stiffness pendulum isolator (VSPI) in order to effectively adapt the system under service conditions and near-fault excitations [15].…”