混凝土框架内节点受剪承载力计算模型和方法研究

Study on analytical models and improvement for the shear loading capacity of reinforced concrete beam-column interior joints

对钢筋混凝土框架内节点受剪承载力计算模型,即受剪通用分析模型和简化拉-压杆模型进行了系统的总结和分析,并利用国内已有的试验结果分析对比了两种模型预测结果的准确性。在框架内节点试验结果的基础上提出了节点核心区名义剪力的改进计算方法。改进的节点名义剪力计算方法能够考虑梁端剪力的往复作用,提高了试验中内节点水平剪力实际值的精确性。对受剪通用分析模型从原理上进行了分析,指出节点受剪通用分析模型的改进需要考虑柱轴压力对核心区混凝土裂缝的约束作用。通过考虑梁端往复荷载作用下梁受压区混凝土高度,改进了简化拉-压杆模型设计方法;与实际值的对比分析表明,改进简化拉-压杆模型计算结果与实际值更为接近且较为保守,改进模型计算结果与试验结果的平均比值为0.85。

The shear capacity models, i. e. , the general analytical model and the simplified softened strut-and-tie model, for reinforced concrete beam-column interior joints were systematically summarized. The precision of predicted results by two models was compared with the available test data. A improved calculation method for the pseudo shear of the beam- column interior joints under cyclic loading was proposed to increase the accuracy of real horizontal shear force of the joints, which can take into account the cyclic effect of shears on the beam ends. Through the principle analysis of the general analytical model, it is suggested that the confining effect of the axial compressive force of the column on cracks of the core concrete should be considered to improve the general analytical model. The simplified softened strut-and-tie model was improved by considering the height of compression zone of beams subjected to cyclic loading. It has been proved by test data that predicted results with the improved simplified softened strut-and-tie model is consistent with the test data and conservative. The average ratio of predicted results by the improved model and test results is 0. 85.