PVC-CFRP管混凝土柱-钢筋混凝土环梁T型节点拟静力试验与弯矩-曲率恢复力模型研究

PSEUDO-STATIC TEST AND MOMENT-CURVATURE HYSTERTIC MODEL OF PVC-CFRP CONFINED COLUMN-RC RING BEAM EXTERIOR JOINT

开展11根PVC-CFRP管钢筋混凝土柱-钢筋混凝土环梁T型节点低周反复加载试验,分析环梁尺寸、环筋配筋率、CFRP条带间距、梁纵筋配筋率、轴压比等因素对其破坏形态、滞回性能、骨架曲线等影响。结果表明:节点破坏经历初裂、通裂、极限和破坏四个阶段,节点的弯矩-曲率滞回曲线包括弹性段、弹塑性段和平稳段,节点滞回环饱满,显示出良好的抗震性能。基于软化混凝土本构关系模型,考虑各因素对骨架曲线特征点的影响,提出骨架曲线特征点简化计算公式。基于退化三线型恢复力模型,给出卸载刚度计算公式,提出节点滞回规则,建立预测精度较高的环梁节点弯矩-曲率恢复力模型。

Eleven PVC-CFRP confined concrete column-reinforced concrete ring beam exterior joints are tested under low cyclic loading.The effects of the ring beam width,reinforcement ratio of ring reinforcement,spacing of CFRP strips,reinforcement ratio of frame beam and axial compression ratio on the failure mode,hysteretic behaviors and skeleton curves are analyzed.The test results show that the failure of typical specimens experiences four stages,i.e.,initial crack,crack penetration,limit and failure.The moment-curvature hysteretic curve consists of elastic stage,elastic-plastic stage and stationary stages.The hysteresis loops are full,indicating that the specimens exhibit excellent seismic behaviors.By considering the effects of the above parameters on the characteristic points of moment-curvature skeleton curves,the simplified formulas for predicting the characteristic points are proposed based on the softening constitutive model of concrete.On the basis of the degenerate trilinear hysteretic model,the calculation formula for unloading stiffness and the hysteretic rule are proposed,and a moment-curvature hysteretic model of the joints is established with high accuracy.