Li Long-Shan, Hui Ying-Xin, Wang Jie, Zhang Ya-Jun
Ningxia Haiping Expressway Management Co., Ltd., Zhongwei, 755200, China.
Ningxia Communications Construction Co., Ltd., Yinchuan, 750004, China.
Heliyon. 2024 Aug 28;10(17):e36932. doi: 10.1016/j.heliyon.2024.e36932. eCollection 2024 Sep 15.
Girder shifting is a common form of seismic damage for girder bridges. Unseating could occur when the displacement of the girder is too large, especially for bridges near faults, because the velocity impulse effect leads to greater displacement responses of structures. Setting metal dampers between girders and piers is a useful way to control the seismic behavior and reduce the risk of unseating. Since metal dampers are inevitably exposed to the erosive service environments, their mechanical properties may degrade due to corrosion. In this paper, a U-shaped metal damper made of stainless steel instead of mild steel (i.e., U-shaped stainless steel damper, which could be named simply as USSSD) is proposed and applied to the seismic reduction design of girder bridges. First, the finite element model (FEM) of the USSSD is built by the ABAQUS, and its force-displacement relationship is obtained based on the skeleton curve, which is fitted by the trilinear kinematic strengthening model. Then, a multi-union long simply supported girder bridge is taken as an example. The FEM of the adopted bridge is established via the Midas Civil to verify the seismic mitigation effect of the proposed USSSD excited by near-fault ground motions. The numerical analyses demonstrate that the unseating may occur without the use of the USSSDs. The relative displacement between the girder and pier is effectively controlled by the USSSDs, and the reduction is more than 50 %. When the bridge is equipped with the USSSDs, both the curvature ductility coefficient of the pier bottom and the maximum drift of the pier tip increase by a limited amplitude, which do not cause additional damage to the piers.
梁体移位是梁式桥常见的地震破坏形式。当梁体位移过大时可能会发生落梁现象，对于靠近断层的桥梁尤其如此，因为速度脉冲效应会导致结构产生更大的位移响应。在梁体与桥墩之间设置金属阻尼器是控制桥梁抗震性能和降低落梁风险的有效方法。由于金属阻尼器不可避免地暴露在侵蚀性服役环境中，其力学性能可能会因腐蚀而退化。本文提出了一种由不锈钢而非低碳钢制成的U形金属阻尼器（即U形不锈钢阻尼器，可简称为USSSD），并将其应用于梁式桥的减震设计中。首先，利用ABAQUS建立了USSSD的有限元模型（FEM），并基于骨架曲线得到其力-位移关系，该骨架曲线由三线性运动强化模型拟合。然后，以一座多联长简支梁桥为例。通过Midas Civil建立了所采用桥梁的有限元模型，以验证在近断层地面运动作用下所提出的USSSD的减震效果。数值分析表明，不使用USSSD时可能会发生落梁现象。USSSD有效地控制了梁体与桥墩之间的相对位移，减少量超过50%。当桥梁安装了USSSD时，桥墩底部的曲率延性系数和桥墩顶部的最大位移均有限度地增加，不会对桥墩造成额外损伤。
