基于干接缝单元的预制拼装桥墩抗震性能数值模拟

为克服利用OpenSEES进行预制拼装桥墩纤维模型分析时干接缝区域模拟困难的问题,提出一种由刚性单元、非线性梁柱单元、零长度单元配合ENT单压材料组成的干接缝单元。通过基于干接缝单元的纤维模型数值模拟结果与文献中的1:3.5缩尺桥墩拟静力试验结果对比发现:该干接缝单元不仅解决了墩身混凝土压溃带来的模型不收敛问题,而且考虑了墩身节段宽度对干接缝区域的影响,使预制拼装桥墩干接缝处的力学性能更接近实际的力学性能;数值模拟结果与试验结果吻合较好证明了该干接缝单元用于模拟预制拼装桥墩干接缝区域的可行性。在此基础上设置耗能钢筋、外包钢管和墩底橡胶支承垫层作为桥墩附加耗能装置,对预制拼装桥墩进行拟静力循环加载模拟,研究不同耗能装置对预制拼装桥墩的滞回能力、预应力筋内力、累积耗能、残余位移以及等效刚度等性能参数的影响。结果表明:设置耗能钢筋和外包钢管可以显著提高预制拼装桥墩的耗能能力、水平承载力和刚度,降低预应力损失;设置墩底橡胶支承垫层也能提高预制拼装桥墩的耗能能力,但会降低桥墩的水平承载力和刚度,应根据桥墩自身刚度谨慎选择橡胶垫层的刚度。

Numerical simulation of seismic performance of precast segmental bridge piers based on Dry Joint Element

In order to overcome the difficulties of the dry joint area in the numerical analysis of precast segmental bridge piers fiber model by using OpenSEES. A Dry Joint Element composed of rigid element, nonlinear beam-column element, zero-length element and ENT single-pressure material was proposed. The numerical simulation results of the fiber model based on the Dry Joint Element and the quasi-static tests of 1:3.5 scale pier in the literature were compared. The compared results showed that the Dry Joint Element not only solves the problem of model non-convergence caused by pier concrete crushing, but also considers the influence of pier section width on dry joint area, so that the mechanical properties of the dry joint of precast segmental bridge piers are closer to the actual mechanical properties. The numerical simulation results are in good agreement with the testresults, which proves that the Dry Joint Element can be used to simulate the dry joint area of precast segmental bridge piers. On this basis, the quasi-static cyclic loading simulation of precast segmental bridge piers was carried out;these piers consisted of energy dissipating bars, outside steel tubes and pier bottom rubber bearings as additional energy dissipation devices. The effects of different energy dissipation devices on the hysteretic capacity, internal force of prestress tendons, cumulative energy dissipation, residual displacement and equivalent stiffness of precast segmental bridge piers were investigated.The results showed that the energy dissipation capacity, horizontal bearing capacity and stiffness of precast segmental bridge piers can be significantly improved by setting energy dissipation bars and outside steel tubes, and the of prestress loss can be reduced. The energy dissipation capacity of precast segmental bridge piers can also be improved by setting pier bottom rubber bearings, but the horizontal bearing capacity and stiffness of piers can be reduced. The stiffness of rubber bearings should be carefully selected according to the stiffness of piers.