SMA限位对铁路自复位桥墩地震反应的影响

Effect of SMA Restrainer on Seismic Response of Railway Self-centering Pier

为研究形状记忆合金(SMA)对铁路自复位桥墩地震反应的影响,在已验证的两弹簧模型上增加SMA限位单元,以某铁路桥墩为工程背景,基于OpenSees平台建立数值分析模型,通过输入3条强震记录,采用非线性时程分析方法进行SMA限位的桥墩影响分析。讨论SMA限位装置关键参数初始间隙、初始预加力变化对墩顶位移和墩底弯矩的影响规律,并与预应力钢筋限位进行比较。研究结果表明:在普通地震动El-Centro与Taft波下,自复位桥墩的墩顶位移随限位装置初始间隙δ减小而减小,墩底弯矩随初始间隙δ减小而增大;随SMA限位装置初始预加力增大,自复位桥墩的墩顶位移减小,墩底弯矩增大。在近断层地震动Northridge下,SMA限位对自复位桥墩地震反应的影响复杂。在3条强震记录下,与预应力筋限位相比,SMA限位会减小墩底弯矩,增大墩顶水平位移。

In order to study the influence of shape memory alloy(SMA) on the seismic response of railway self-centering piers,the SMA restrainer element is added to the verified two-spring model.Taking a railway bridge pier as the engineering background,the numerical analysis model is established based on OpenSees platform.By inputting three strong earthquake records,the influence of SMA restrainer on the pier is analyzed by nonlinear time history analysis method.The influence of the initial clearance and the change of the initial prestress of the key parameters of the SMA restrainer device on the displacement of the pier top and the bending moment of the pier bottom is discussed,and compared with the prestressed reinforcement restrainer.The results show that under ordinary ground motion El-Centro and Taft waves,the displacement at the top of the self-centering pier decreases with the decrease of the initial gap δ of the restrainer device,and the bending moment at the bottom of the pier increases with the decrease of the initial gap δ.With the increase of the initial preload of the SMA restrainer,the displacement of the top of the self-centering pier decreases and the bending moment of the bottom of the pier increases.The influence of SMA restrainer on the seismic response of self-centering piers under near-fault ground motion Northridge is complex.Under three strong earthquake records,compared with the prestressed reinforcement restrainer,SMA restrainer will reduce the bending moment of the pier bottom and increase the horizontal displacement of the pier top.