A multi-level performance SMA-based isolation system in girder bridges

During the near-fault earthquake action, isolated bridges experience significant in-plane displacement and residual displacements, which may cause the bridge girders to unseating and even complete collapse. In this paper, a multi-level performance SMA-based isolation system was proposed. This device consists of 3-levels of SMA cables and conventional isolators, which are assembled in parallel. With the intensity of earthquake increasing, each level of SMA cables will be activated in a sequence to meet different performance requirements. Based on OpenSees and Sap2000 platforms, the lateral restoring force-displacement relationship and the hysteresis model of a specific SMA-based isolator was explored. The effectiveness of the two platforms for simulating the isolator was also investigated. Furthermore, a case study of a continuous bridge was conducted and parameter analysis about effective sectional area was conducted to testify the effectiveness of the isolation system in multi-level aseismic design. It turns out that this device has better displacement reduction, restoration, and energy dissipation capability. In addition, it has the advantages of multi-level performances, which ensures itself a bright prospect in application. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.