铁路圆端空心墩等效塑性铰长度试验研究

Tests on Equivalent Plastic Hinge Length of Railway Round-ended Hollow Piers

等效塑性铰长度通常用于估算桥墩顶部的位移能力,是空心墩抗震性能分析的重要指标之一。鉴于目前塑性铰长度公式大多源于实心构件的试验和理论成果,铁路圆端空心墩的塑性铰特性、现有计算模型的适用性等亟待深入研究。因此,对4个1/6缩尺的圆端空心墩模型进行拟静力加载,观测试件损伤演化历程,分析桥墩塑性铰和曲率分布特性,并比较既有塑性铰长度公式计算值与实测值。结果表明:最终墩身裂缝分布范围约占桥墩高度的2/3,塑性损伤主要集中在墩底空心墩倒角附近区域;由于墩底实心段、倒角过渡段和墩身变截面的影响,墩底塑性铰区相对延长并整体上移;Eurocode8模型计算结果与试验值最为接近,可用于估算铁路圆端空心墩等效塑性铰长度。

The equivalent plastic hinge length,usually applied to the estimation of the displacement capacity of the top of a pier,is one of the significant parameters for seismic performance analysis of a hollow pier.Given that the existing plastic hinge length formulas are mostly based on the experimental and theoretical results of solid members,the plastic hinge properties of round-ended hollow piers and the applicability of existing models require further study.Therefore,quasi-static tests of four 1/6-scale round-ended hollow pier specimens were conducted,to observe the damage evolution of the specimens,and to analyze the distribution properties of plastic hinge and curvature of the piers.Finally,a comparison of computational and experimental results was implemented.The results show that final pier body cracks account for around 2/3 of the height of the pier and the plastic damage mainly occurs within the internal chamfering region near the pier base.The plastic hinge zone of the pier base is extended relatively and moves up as a whole due to the influence of solid segment of the pier base,internal chamfering,and the variable cross-section of the pier body.The prediction of Eurocode8 model is the closest to the measured values,which can be used to estimate the equivalent plastic hinge length of round-ended hollow piers.