基于OpenSees的节段拼装桥墩抗震性能数值分析

Numerical Analysis for Seismic Behavior of Segmental Assembly Piers Based on OpenSees

为对预应力混凝土节段拼装桥墩抗震性能的数值分析提供依据,应用OpenSees有限元计算程序,选取非线性纤维梁柱单元配合适当的材料本构模型,对桥墩的混凝土节段、接缝及预应力筋进行模拟。首先,介绍桥墩材料所选用的本构模型;然后,介绍模型对各部件的模拟方法、纤维网格划分以及边界条件设置;其次,开展模型分析并将计算结果与拟静力试验进行对比,结果表明:试验的滞回曲线、骨架曲线特性得到较好模拟;再次,探究并得到往复荷载作用下,P-Δ效应和墩底核心区混凝土强度退化是引起桥墩承载力降低的主要原因;最后,利用模型讨论了预应力张拉力、纵筋配筋率、混凝土强度、箍筋配筋率对桥墩骨架曲线的影响,发现张拉力相对其他几项参数对试件最大承载力的影响最为明显,混凝土强度对试件延性的影响最为明显。

The OpenSees finite element calculation program was used to simulate the concrete segments,joints and prestressed tendons of bridge piers by selecting nonlinear fiber beam-column elements with appropriate material constitutive model which provided a theoretical basis for numerical analysis of the seismic performance of prestressed concrete segmental bridge piers.First of all,the constitutive model of the pier material,the simulation method of each component,fiber mesh division and boundary condition setting were introduced.Then,the model analysis was carried out and it was found that the P-Δeffect and the concrete strength degradation in the core area of the pier bottom are the main reasons for the reduction of the bearing capacity of the bridge pier under the action of reciprocating loads.In addition,a good agreement between the calculated results and the pseudo-static tests was demonstrated,indicating that the characteristics of the test hysteresis curve and skeleton curve are well simulated.Finally,the influence of prestressing force,longitudinal reinforcement ratio,concrete strength,and stirrup reinforcement ratio on the pier skeleton curve were discussed by using the model.The results show that the tensile force has the most obvious influence on the maximum bearing capacity of the specimen compared with other parameters.The influence of strength on the ductility of the specimen is the most obvious.