氯盐侵蚀RC节点抗震性能与数值模拟方法

Seismic behavior and numerical modelling method of RC joints due to chloride erosion

为研究近海环境中钢筋混凝土(RC)框架节点的抗震性能,设计了4榀RC框架中节点试件,采用人工气候环境加速腐蚀模拟技术对其进行氯盐侵蚀,进而进行拟静力试验,分析氯盐侵蚀引起的钢筋锈蚀对RC框架节点承载能力、变形能力及核心区剪切性能的影响;同时,采用OpenSees中Joint2D单元模拟节点核心区,用弹性杆单元模拟梁、柱,建立了锈蚀RC框架节点组合体数值模型,对锈蚀RC框架节点的滞回特性进行了数值模拟.结果表明:在氯盐侵蚀作用下,试件表面出现红褐色锈蚀产物与锈胀裂缝,且随氯盐侵蚀程度增加该现象不断加重;随着钢筋锈蚀程度加重,试件承载能力、变形能力、延性、核心区抗剪性能等均有不同程度退化;模拟结果与试验结果在承载力、变形能力、捏缩特性等方面均符合较好,验证了该建模方法的准确性.

To investigate the seismic behavior of reinforced concrete(RC) beam-column joints in the coastal atmosphere, four corroded RC beam-column joints specimens were subjected to accelerated corrosion in a simulated chloride salt environment. The quasi-static tests were carried out and the influence of the corrosion of reinforcing steel caused by chloride salt erosion on the bearing capacity, deformation capacity and shear performance of specimens were analyzed. In the meantime, the joint 2 D element in Open Sees was used to simulate the joint core area, and the elastic bar element was used to simulate the beam and column. The numerical model of the corroded RC frame joint was established, and the numerical simulation of the hysteretic characteristics of the corroded RC frame joint was carried out.The results reveal that the red-brown rust products and rust expansion cracks appear on the surface of the RC beam-column joints due to the erosion chloride salt, and that the erosion phenomenon is severer with the prolongation of the corrosion. With the increase in the degree of steel corrosion, the bearing capacity, deformability, ductility,and shear behavior of the specimens all deteriorate in varying degrees. The simulation results are in good agreement with the test results in terms of bearing capacity, deformation capacity and pinch shrinkage characteristics, which verify the accuracy of the modeling method in this paper.