轴压下钢筋混凝土桥墩塑性铰特性研究  

Study on the Characteristics of Plastic Hinge of Reinforced Concrete Pier under Axial Load

作　　者：李徐[1] 钟铁毅[1] 夏禾[1] 王飞[1] 顾正伟[2] 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]吉林大学交通学院,吉林长春130021

出　　处：《中国铁道科学》2014年第1期34-41,共8页China Railway Science

基　　金：铁道部科技研究开发计划项目(2008G010-A);优秀博士生创新基金项目(2012YJ074)

摘　　要：通过2个大尺寸钢筋混凝土桥墩在轴压下的水平低周往复加载试验,并结合混凝土压应变方法和基于OpenSEES的数值方法,研究钢筋混凝土桥墩的塑性铰特性,分析轴压对塑性区域长度及等效塑性铰长度的影响规律。结果表明:随轴压的增大,桥墩截面受压区应变增大,桥墩发生塑性破坏区域的长度显著增加,既有规范按1.0倍的桥墩截面高度估计塑性区域长度在高轴压下偏于不安全,故建议当桥墩轴压比超过0.2时,加密布筋的塑性区域长度应增大至1.5倍的桥墩截面高度;随着轴压增大,桥墩位移延性的下降大于截面曲率延性下降的幅度,从而使等效塑性铰长度不断减小,因此在推导等效塑性铰长度时应考虑轴压的影响,以免在轴压较大时过高估计桥墩延性,带来安全隐患。By means of horizontal low-cyclic repeated loading test on two samples of large-sized reinforced concrete piers under axial load,in parallel with concrete compressive strain method and on the basis of OpenSEES numerical method,the plastic hinge characteristics of reinforced concrete piers were studied and the influence laws of axial load on the length of plastic zone and length of equivalent plastic hinge were analyzed.The results show that along with the increase of axial load,the strain on the compressed area of pier column cross-section increases and the length of plastic failure area which appears on piers obviously increases.For the existing specification,the estimation of plastic area length under high axial load according to 1.0 time of pier cross-section height tends to be unsafe,thus we propose when the axial compression ratio of pier column exceeds 0.2,the length of plastic area for the densified bar arrangement should be increased to 1.5 times of pier cross-section height.Along with the increase of axial load,the reduction of pier displacement ductility is larger than the reduction amplitude of cross-section curvature ductility,consequently making the length of equivalent plastic hinge continuously decrease.Therefore,when inferring the length of equivalent plastic hinge,the effect of axial load should be taken into account,so as to avoid the situation that,when the axial load is larger,the pier ductility is over evaluated and a potential safety risk occurs along with.

关 键 词：钢筋混凝土桥墩 塑性区域长度 塑性铰长度 拟静力试验 延性 

分 类 号：U443.22[建筑科学—桥梁与隧道工程]