基于改进拉压杆模型的PC框架节点抗剪强度预测

Shear strength prediction of prestressed concrete beam-column joints based on modified strut-and-tie model

针对预应力混凝土(PC)框架节点抗剪强度合理计算模型的缺乏,建立了一个显式考虑预应力效应的改进拉压杆模型。依据Kupfer-Gerstle双向拉压强度准则,考虑了节点核心区混凝土软化效应,并基于此准则推导了一个简便实用的受剪承载力预测公式。通过对文献中21组内、外节点进行分析,得到试验值与模型预测结果的平均比值为1.14,离散系数为0.139,表明本文公式预测结果较精确、连续且偏于安全,而且还优于《混凝土结构设计规范》(GB 50010—2010)中的设计方法,可用于有、无粘结PC框架节点的抗震设计。

Due to the scarcity of rational models for predicting the shear strength of prestressed concrete （PC） beam-column joints, a modified strut-and-tie model was established. In the proposed model, the effect of prestress was explicitly taken into account. Kupfer-Gerstle biaxial tension-compression failure criterion of concrete was utilized to take account of the concrete softening effect, based on which a simple and convenient formula was derived. A comparison of 21 exterior and interior beam-column joints shows that the model predictions were accurate, consistent and conservative with an overall average test result to prediction of 1.14 and a coefficient of variation of 0. 139, and also illustrate its superior accuracy over the design method of Code for design of concrete structures （GB 50010--2010）. It indicates that the proposed model can be employed for design of PC beam-column joints with bonded and unbonded tendons.