R-UHPC梁的抗剪承载力计算方法

收集了大量的配筋超高性能混凝土(R-UHPC) 梁抗剪承载力的试验数据, 分析了现有抗剪承载力计算方法, 研究了R-UHPC梁的抗剪机理, 考虑了UHPC的抗拉作用, 提出了基于桁架-拱模型的R-UHPC梁抗剪承载力计算方法, 并比较了计算结果与试验结果。比较结果表明: 在现有的计算方法中, 采用基于统计分析方法的承载力计算值与试验值的平均比值为0.92, 比值的标准差为0.23, 比值的相关性系数为0.78, 比值的可靠性系数为0.877, 该方法因回归数据有限, 精度不高; 对于基于一般桁架模型的梁抗剪承载力计算方法, 法国UHPC指南AFGC抗剪承载力计算值与试验值的平均比值为0.90, 比值的标准差为0.18, 比值的相关性系数为0.80, 比值的可靠性系数为0.891, 计算精度较日本UHPC标准JSCE和瑞士标准SIA较高; 在AFGC指南基础上, 考虑了纵筋影响, 抗剪承载力计算值与试验值平均比值为0.93, 比值的标准差为0.23, 比值的相关性系数为0.75, 比值的可靠性系数为0.858, 与AFGC计算结果相比离散性较大; 采用基于桁架-拱模型的抗剪承载力计算方法的抗剪承载力计算值与试验值平均比值为0.76, 比值的标准差为0.26, 比值的相关性系数为0.62, 比值的可靠性系数为0.768, 因直接套用钢筋(普通) 混凝土梁的抗剪承载力计算方法且不计UHPC的抗拉作用, 计算结果过于保守, 且可靠性最差; 采用提出的抗剪承载力计算方法的计算值与试验值的平均比值为0.94, 比值的标准差为0.21, 比值的相关性系数为0.80, 比值的可靠性系数为0.885, 与现有计算方法相比, 本文提出计算方法精度较高, 离散性小。

Calculation method of shear bearing capacity of R-UHPC beam

A lot of test data of shear bearing capacity concerning reinforced ultra-high performance concrete (R-UHPC) beams were collected, existing calculation methods of shear bearing capacity were analyzed, and the shear bearing mechanism of R-UHPC beam was studied.The tensile strength of UHPC was considered, a calculation method of shear bearing capacity for R-UHPC beam based on truss-arch model was presented, and the calculated result and test result of shearbearing capacity were compared.Comparison result indicates that in the calculation methods at present, based on statistical analysis method, the average ratio of the calculation values to the test values of shear bearing capacity is 0.92, its standard deviation, correlation coefficient and reliability coefficient are 0.23, 0.78 and 0.877, respectively, and the computation accuracy is not high due to the limitation of regression data.For the calculation methods based on the general truss model, the average ratio of the calculation values to the test values of shear bearing capacity with AFGC in French UHPC is 0.90, its standard deviation, correlation coefficient and reliability coefficient are 0.18, 0.80 and 0.891, respectively, and the computation accuracy is higher than the accuracies of Japan UHPC's JSCE and Swiss SIA. When the effect of longitudinal reinforcement is considered based on AFGC, the average ratio of the calculation values to the test values of shear bearing capacity is 0.93, its standard deviation, correlation coefficient and reliability coefficient are 0.23, 0.75 and 0.858, respectively, and the result has larger discreteness than the result of AFGC.For the calculation methods based on the truss-arch model, the average ratio of the calculation values to the test values of shear bearing capacity is 0.76, and its standard deviation, correlation coefficient and reliability coefficient are 0.26, 0.62 and 0.768, respectively.Because the computation methods of shear bearing capacity of reinforced (common) concrete beam are straightly applied and the tensile strength of UHPC is neglected, the result is conservative and most unreliable.For the proposed calculation method of shear bearing capacity, the average ratio of the calculation values to the test values of shear bearing capacity is 0.94, and its standard deviation, correlation coefficient and reliability coefficient are 0.21, 0.80 and 0.885, respectively.Compared with the calculation methods at present, the proposed method has higher precision and less discreteness.