Seismic Behavior of Superelastic Shape Memory Alloy Spring in Base Isolation System of Multi-Story Steel Frame.

Yuping Liu,Xingnan Zhao,Hongyang Wang,Canxing Qiu

doi:10.3390/ma12060997

Abstract

Owing to excellent re-centering capability and good damping behavior, superelastic shape memory alloys (SMAs) are emerging as a potential new material to enhance the seismic resilience of civil structures. This paper focuses on using base isolation with SMA device for isolated structures. SMA springs are deemed to be promising candidate as the damper in the base isolation system, due to the compact form, damping contribution, restoring capability and flexible stiffness. This paper reported the concept of an innovative spring which is made of superelastic SMA wire. Then cyclic loading tests were carried out to evaluate the interested cyclic properties. Parametric analyses based on finite element simulations were conducted to reveal the versatile performance of SMA springs. To further examine its seismic behavior in the base isolation system, the SMA spring was later installed at the isolation level of a multi-story steel frame, based on the finite element model built in the earthquake engineering simulation platform OpenSees. An ordinary elastic spring is included for comparison to highlight the features of SMA springs. Both isolated frames were subjected to real earthquakes. The comparisons indicated that using SMA spring is more effective in controlling maximum and residual deformation for the protected superstructures. Thus, this paper well demonstrated the feasibility and merits of using SMA springs in the isolated frames.

Highlights

Using seismic isolators has been found an effective way to protect low- to middle- rise structures under earthquakes in past investigations and practices [1]
This paper examined the seismic behavior of superelastic shape memory alloys (SMAs) spring in the isolation system of
This paper examined the seismic behavior of superelastic SMA spring in the isolation system of multi-story steel frame

Summary

Introduction

Using seismic isolators has been found an effective way to protect low- to middle- rise structures under earthquakes in past investigations and practices [1]. According to the principle of structural dynamics, seismic isolators are required to have much smaller lateral stiffness than that of the protected superstructure. The allowable deformation space for isolation system is usually limited by the adjacent structures or foundations. As reported in the Northridge earthquake [3], the limited isolation gap generated suddenly increased shear force and interstory drift in the superstructure as a result of the pounding impact. It is advisable to achieve a balance between controlling deformation for the isolators and alleviating the counter effect of increasing seismic demand in the superstructure

Methods

Results

Conclusion