钢筋混凝土墩柱弯剪数值模型对比研究

Comparative study on flexural-shear numerical model of reinforced concrete pier column

为探究弯剪和剪切破坏墩柱的抗震性能及反映墩柱弯剪破坏机制的数值分析模型,依据弯剪及剪切破坏墩柱的拟静力试验结果,考虑剪跨比和截面配箍率对墩柱抗剪及延性变形能力的影响,提出了剪切破坏时墩柱塑性铰区转角的计算公式,并与Leborgne公式及Ghannoum公式进行了比较;基于OpenSees数值分析平台,从截面层次和单元层次分别建立了考虑弹性剪切效应及弯剪耦合效应的两种精细化分析模型,以PEER数据库中试验墩柱结果进行了数值分析模型验证。结果表明:所提公式能更精确地监测墩柱剪切破坏发生时刻,考虑弯剪耦合效应的数值模型能较好地模拟钢筋混凝土墩柱抗剪强度、刚度退化及捏拢现象,与试验结果吻合较好;考虑弹性剪切效应的数值模型不能较好地体现剪切失效与刚度退化。

In order to explore the seismic performance of flexural shear and shear failure pier column and numerical analysis model,reflecting bending-shear failure mechanism of pier column based on the quasi-static test results of flexural shear and shear failure pier columns,considering the influence of shear-span ratio and section hoop ratio on the shear strength and ductile deformation ability of pier columns,a formula for calculating the rotation angle of plastic hinge area of pier columns at the moment of shear failure was proposed.The proposed formula was compared with Leborgne formula and Ghannoum formula.Based on the OpenSees numerical analysis platform,two refined analysis models considering elastic shear effect and bending-shear coupling effect were established from section level and element level respectively,and the numerical analysis model was verified by the test pier column results in PEER database.The results show that the proposed formula can monitor the moment of shear failure more accurately,and the numerical model considering the coupling effect of bending and shear can simulate the shear strength,stiffness degradation and pinching phenomenon of reinforced concrete pier column better,which is in good agreement with the test results.The numerical model considering elastic shear effect can not well reflect shear failure and stiffness degradation.