组合式剪力键预制拼装桥墩结构及其抗震性能研究

Precast segmental bridge pier structure with combined shear keys and seismic performance analysis

针对预制拼装桥墩地震下抗剪扭能力薄弱的不足,提出一种组合式钢套筒(销棒)剪力键预制拼装桥墩结构方案。基于ABAQUS平台,发展并检验了可考虑复杂非线性力学行为的实体模型模拟方法。开展拟静力分析,系统讨论了预应力筋及剪力键主要参数对桥墩抗震性能的影响规律,并选取近远场地震动开展非线性动力分析进行了有效性检验。结果表明,提高预应力筋配筋率可显著增强桥墩的抗剪能力,但也会相应增加强震下的残余位移;通过合理设置预应力筋配筋率,可使预制拼装桥墩具有与现浇整体墩相当的承载力;增大剪力键埋深和钢销棒直径可有效提高桥墩的抗剪能力,但应合理控制剪力键最小埋深和钢销棒最大直径;双向水平地震作用下,组合式剪力键可有效限制接缝张开及滑移扭转变形,显著提高桥墩的抗剪扭能力。

Aiming at the shortage of shear and torsion resistance capacity of precast segmental bridge pier under earthquake excitation,the combined steel sleeve(dowel)shear keys were developed,and a new structural scheme for precast segmental pier was proposed.Based on the ABAQUS platform,a simulation method with solid finite elements was developed and tested,and the complex nonlinear mechanical behaviors were considered in the model.The effects of main parameters of tendon and shear keys were systematically discussed by quasi-static analysis.In addition,near and far field ground motions were selected for nonlinear dynamic analysis,and the effectiveness of combined shear keys was also tested.The results show that,shear resistance capacity of pier can be enhanced by improving tendon ratio;however,the residual displacement under strong earthquake is increased accordingly.By properly setting the tendon ratio,the maximum strength of a precast segmental bridge pier can be equivalent to that of a cast-in-place pier.Moreover,increasing the embedded depth of shear key and the diameter of steel dowel can effectively improve the shear resistance capacity of the bridge pier,the minimum embedded depth of shear key and the maximum diameter of steel dowel should be reasonably controlled.Furthermore,under bidirectional ground motions,the combined shear keys can not only effectively limit the joint opening,slip and torsion deformation,but also significantly improve the shear and torsional capacity of the pier.