基于纤维梁柱单元的桥梁墩柱地震反应模拟方法研究

为讨论利用纤维梁柱单元进行钢筋混凝土桥墩地震反应分析的建模方法，分别以4个悬臂式单柱墩和1个双柱墩拟静力加载试验，以及1个悬臂式单柱墩的振动台试验结果为依据，基于OpenSees数值分析平台建立了桥墩的地震反应分析模型。通过改变单元数量，分析了基于力的纤维梁柱单元和基于位移的纤维梁柱单元对桥墩地震反应的模拟精度。结果表明:对悬臂式单柱墩的拟静力和振动台试验，可沿墩高仅建立1个基于力的纤维梁柱单元，并在墩底串联1个考虑纵筋塑性渗透和粘结滑移的转动弹簧单元，即可获得很好的模拟结果。当采用基于位移的纤维梁柱单元时，应沿墩高至少建立2个单元，且塑性铰区至少有1个，才能保证获得较高的模拟精度。对双柱墩拟静力试验，采用基于力的纤维梁柱单元建模，沿每个墩高建立2个单元即可；以基于位移的纤维梁柱单元建模，建议沿每个墩高建立3个单元，且其中2个单元布置在塑性铰区。当数值模型可对静力滞回曲线取得很好的模拟结果后，该模型一般可对动力作用下墩顶最大位移和墩底最大剪力进行较为准确的模拟，但对墩顶残余位移的模拟精度无法保证。

Research on the simulation method for the seismic responses of bridge piers by using fiber beam-column elements

To investigate the modeling method for the seismic response analysis of the reinforced concrete bridge piers by using fiber beam-column elements,different models for the piers were built based on OpenSees platform.The effectiveness of the models were verified by comparing the simulation results with the quasi-static test results of four cantilever single column piers and one double-column bridge bent,and the shaking table test results of one cantilever single column pier.By changing the number of the fiber beam-column elements,the simulation accuracy of the models using either force-based or displacement-based beam-column element was discussed.It is shown from the comparison results for both the quasi-static and shaking table tests of the cantilever column pier that only one force-based beam-column element with a rotation spring element to consider the longitudinal bar penetration and bond slip deformation is enough.While at least two displacement-based beam-column elements with one in the plastic hinge zone should be used to ensure the accuracy of the model.For the quasi-static test results of a double-column bent,only one force-based beam-column element along the length of each pier will be enough to model the behavior of the bent,while at least three displacement-based beam-column elements with two in the plastic hinge regions of each pier is required.When the model is able to reasonably simulate the hysteretic curve of the pier under quasi-static test,the model usually gives a good simulation on the maximum displacement and the maximum shear force,but the simulation accuracy for the residual displacement of the pier may not be guaranteed.