廊桥壁式桥墩的数值分析模型对比研究

Comparative study on numerical analysis models of the wall pier of covered bridge

以一座梁式廊桥的壁式桥墩为例,基于有限元分析软件OpenSees,分别采用分层壳单元和纤维梁单元对其进行弱轴方向上的低周反复加载下的数值分析,对比研究了2种数值模型的滞回曲线和骨架曲线,并在位移延性比的基础上,给出了壁式桥墩各破坏状态的指标临界值。结果表明:分层壳单元模型和纤维梁单元模型均能很好地模拟壁式桥墩的承载力变化、剪切效应以及损伤累积,但前者可以更明确地表征不同侧向荷载加载方式下局部位置的抗震性能。同一损伤状态下,分层壳单元模型和纤维梁单元模型得出的壁式桥墩位移延性比差异较小。文中壁式桥墩基于位移延性比的损伤状态划分的临界值,可分别取为0.27,1.00,2.33,5.33,验证了采用普通柱式桥墩的损伤状态极限值作为壁式桥墩的各面外损伤指标值的可行性。

Taking the wall pier of a beam-type covered bridge as an example,based on the finite element analysis software OpenSees,the multi-layer shell element and fiber beam element are used to carry out the numerical analysis under low cyclic loading in the weak axis direction.The hysteretic curves and skeleton curves of the two numerical models are compared and discussed.The critical values of the index of each damage state of the wall pier are given on basis of the displacement ductility ratio.The results show that both the multi-layer shell element model and the fiber beam-column element model can simulate the change of bearing capacity,shear effect and damage accumulation of the wall pier well,but the former can clearly characterize the seismic performance of local positions under various lateral loading modes.The results of multi-layer shell element model and fiber beam-column element model under the same damage state demonstrate that there is little difference in the displacement ductility ratio of the wall pier.The critical values of damage state divisions of the wall pier based on the displacement ductility ratio can be taken as 0.27,1.00,2.33 and 5.33 respectively in this case.Meanwhile,it is verified that it is feasible to use the limit values of common pier columns as the index values of each out-of-plane damage state of the wall pier.