钢筋混凝土框架顶层边节点受力模型

MODELING OF LOAD-RESISTANCE MECHANISMS OF REINFORCED CONCRETE KNEE JOINTS

基于以往试验研究提出了针对钢筋混凝土框架顶层边节点的受力模型。研究结果表明:框架顶层边节点强度不但受抗剪机构而且受抗弯机构及锚固机构的影响;正弯矩方向的受力模型与负弯矩方向受力模型不同;负弯矩方向梁筋锚固强度是由其上层筋的弯起段长度、混凝土强度及钢筋直径决定的;正弯矩方向节点抗弯强度是由梁柱筋屈服强度、节点箍筋、柱中间筋和梁柱纵筋在节点内的投影长度决定的。利用该研究受力模型得出的节点强度计算结果与试验结果吻合。

Based on the previous test research findings, the load-resistance models for reinforced concrete knee joints were proposed. It is shown that the joint strength depends not only on shear resisting mechanism but also on moment resisting mechanism as well as anchorage mechanism of the joint. The mechanism in the opening direction differs from that in the closing direction. In the closing direction, the anchorage strength of the beam bars passing through joints is governed by the tail length of the upper bars, the concrete strength, and the diameter of the bars; whereas in the opening direction, the flexural strength of the joints is governed by the yield strength of beam or column bars, the amount of joint hoops, the column interior bars and projection length of beam or column bars in the joint. Predictions of the joint strength by the model presented in this paper agree well with the experimental results.