基于OpenSees的防屈曲支撑加固钢筋混凝土框架数值模拟

Numerical Simulation of Reinforced Concrete Frame Retrofitted with Buckling-restrained Brace Based on OpenSees

提出了一种既有钢筋混凝土框架结构的抗震加固方法,该法采用防屈曲支撑提高框架结构体系的水平承载力和耗能能力,利用外包钢进一步提高柱子的抗弯和抗剪承载力。采用开源有限元程序OpenSees,分别建立空钢筋混凝土框架和防屈曲支撑加固钢筋混凝土框架的分析模型,对2榀钢筋混凝土框架的抗震性能进行模拟。防屈曲支撑采用了弹塑性桁架单元模型,加固框架柱混凝土考虑了外包钢的约束作用。将分析结果与拟静力试验结果进行比较,以检验分析模型的准确性,以及研究防屈曲支撑和外包钢对混凝土框架抗震性能的影响。分析结果表明,数值模拟与试验结果吻合较好,验证了基于OpenSees建立的数值模型的准确性;外包钢有效改善了框架柱的抗弯承载力和变形能力;防屈曲支撑显著提高了加固框架体系的水平刚度、水平承载力和耗能能力。

A seismic retrofit scheme for seismically-weak reinforced concrete（ RC） frame was proposed.The presented method utilized buckling-restrained brace（ BRB） to globally enhance lateral strength and overall energy dissipation capacity of the RC frame,and steel caging was further utilized to locally improve flexural and shear strength of columns. An open-source earthquake engineering simulation system OpenSees was used to develop numerical models of a bare RC frame and a RC frame retrofitted with BRB. The numerical models were developed to simulate seismic behaviors of the RC frames. A simple inelastic truss element was used to simulate the BRB. Confinement of steel cage was taken into consideration in calculating material properties of the column＇s concrete of retrofitted frame. Comparisons of numerical results with that of cyclic tests on the RC frames were conducted. The effects of the BRB and steel caging on seismic performance of RC frames were also investigated. It is shown that good agreements were obtained between numerical and experimental results. The numerical models based on OpenSees were able to predict the seismic behaviors of the RC frames with acceptable accuracy. Steel caging effectively improved flexural strength and deformation capacity of the deficient columns of the RC frame. The BRB significantly increased lateral stiffness,lateral strength,and energy dissipation capacity of the retrofitted frame.