宽梁-薄墙肢梁筋直锚节点试验

在宽梁-薄墙肢节点的弹性有限元分析基础上,对近似足尺的2个宽梁-薄墙肢梁筋直锚节点进行了试验,研究了宽梁节点区的受力和变形性能,特别是纵筋的受力、滑移以及节点区的破坏形态.有限元分析和试验表明:宽梁应伸进墙肢一定的长度,以使宽梁截面的弯曲应力沿着梁截面宽度分布均匀,充分发挥宽梁的抗弯能力;位于墙外侧的宽梁上部纵筋锚固环境较差,如果仅仅满足规范规定的锚固长度,不能保证节点的承载力和延性;节点区的宽梁箍筋对于凸出在墙外的宽梁上部纵筋的锚固具有比较重要的作用.如果节点区的宽梁箍筋数量不足,宽梁在节点区将出现较多斜裂缝,使结构的承载力和延性变差.最后还提出了梁筋直锚型节点受力的空间桁架模型.

Experimental Research on the Behavior of Direct Anchoring Beam-wider-than-wall Joint

Based on the elastic finite element analysis of the RC beam-wider-than-wall joint, two large-scale specimens of the direct anchoring beam-wider-than-wall joint are designed to test the joint behavior. The stresses and slips of longitudinal bars in the beam, load-bearing capacity and destruction form are observed and analyzed. The analysis and test results show that: The wide beam should be extended through into the wall for some length to make the flexural stress uniform along beam section width, thus the beam's bearing capacity can be achieved. The anchorage condition of the upper longitudinal bar in the beam outside the wall's width is poor, thus the anchorage length prescribed in the current CODE is not enough to ensure the bearing capacity and ductility of joints. The beam stirrups are very important to the anchorage of the upper longitudinal bar in the beam outside the wall's width. If the quantity of the beam stirrups is not enough, the wide beam in the joint area would have more cracks which decrease the bearing capacity and ductility of joints. Finally, a novel spatial truss mechanism model for the beam-wider-than-wall joint is put forward.