The Study Of The Seismic Performance Of The Self-centering Pier With SMA Bars

The earthquake damages investigation shows that the larger residual displacement of the pier after the earthquake is one of the main damages of the bridge.The self-centering bridge piers set up a gap between the pier column and the foundation,at the same time,a certain number of energy dissipater and self-centering units are arranged at the gap.Under strong earthquake,the deformation of the pier will be concentrated at the gap,energy dissipater and self-centering units provide respectively energy dissipation and self-centering capability for the pier.The new material shape memory alloy(SMA)has attracted the attention of researchers as a material with super-elasticity property,according to previous studies,shape memory alloy and ordinary steel bar have roughly same yield stress and the restorable strain of SMA is 6%~8%,therefore,shape memory alloys can be used as ideal vibration control materials.Based on the excellent seismic performance of the self-centering bridge piers and the super-elasticity property of shape memory alloys,the article proposes a self-centering bridge piers with SMA bars,the mechanical behavior of piers is analyzed under reciprocating load in theory,then,select reasonable units and constitutive relations,establish models,and analyze seismic performance through pseudo-static and dynamic time history in OpenSees.The main research contents and results are as follows:(1)The development history of the self-Centering bridge piers at domestic and foreign is briefly described,the advantages of the self-Centering bridge piers is demonstrated.The article proposes a self-centering bridge pier with SMA bars,introduces its structure and analyzes its mechanical mechanism in theory.(2)The SMA material tensile model and the self-Centering bridge piers model are established using OpenSees,compare the existing experiments in domestic and explain the correctness of the modeling method,then,propose numerical model of the self-centering bridge piers with SMA bars.There are set up three kinds of piers,the hysteresis curve,residual deformation,structural stiffness etc,of each pier are analyzed and compared,the results show that the self-centering bridge piers with SMA bars has full hysteresis curve,higher energy consumption,smaller residual deformation,strong self-Centering capability.(3)There are parameters analysis of the SMA-SC piers with good seismic performance,changing the parameters of the model,such as: axial load ratio,reinforcement ratio,slenderness ratio,SMA bars diameter,SMA bars placement position,steel column diameter etc,the results show that these parameters about axial load ratio,energy dissipater steel reinforcement ratio,slenderness ratio,SMA bars diameter,steel column diameter etc,have a greater impact on the performance of this pier.(4)There are three near-fault ground motions were selected and get on Dynamic time history analysis of the self-Centering piers with SMA bars.The index about the maximum stress and deformation of the SMA bars,the maximum displacement and residual displacement of the piers are extracted,the results show that the self-centering bridge piers with SMA bars maintains a good self-centering ability under the near-fault ground motion,but the horizontal displacement of the pier is larger,and measures should be taken to control it.