钢管混凝土斜柱抗剪环-环梁节点受力性能试验研究

进行了7个按实际工程2∶3比例缩尺、75°倾斜的钢管混凝土斜柱抗剪环-环梁节点试验。其中5个试件采用单调方式加载,2个试件采用低周反复方式加载。试验过程中,对环梁截面上、下环筋,环梁箍筋以及纵梁纵筋的应变分布及大小进行了量测,记录了试件的荷载-位移曲线。改变试件环梁环筋与纵梁纵筋的比例,改变环梁箍筋形式及加配特殊构造钢筋等措施,对斜柱抗剪环-环梁节点的宏观受力机理、最终破坏形态、受力性能及其影响因素等进行了分析研究。试验结果表明,通过对环梁合理配筋构造,抗剪环-环梁节点能够有效地传递框架梁端的弯矩和剪力;无论最终破坏发生在框架梁端还是环梁内,试件都能达到所要求的承载能力和延性;加大环梁截面高度与纵梁截面高度的比例,可将试件破坏时混凝土的压碎区由环梁斜裂缝下端转移到纵梁端下部,从而形成纵梁端发生弯曲破坏的理想破坏模式。

Experimental research on mechanical behavior of inclined steel tube confined concrete column-ring beam joint with shear ring bars

In this paper, 7 specimens of two-thirds scale and 75-degree inclined steel tube confined concrete column-ring beam joint with shear ring bars were tested under both monotonic loading and cyclic loading. Among them, 5 specimens were tested in monolithic loading and the other two in cyclic loading. Measurement of strains of upper and lower ring reinforcements, along with the stirrups both in the ring beam and the longitudinal reinforcement was made. Load-displacement curves of these specimens were recorded. The mechanism, the ultimate failure mode and the behavior of the joints were analyzed, on the basis of using different ratio of ring reinforcement to longitudinal reinforcement, together with different styles of stirrups and detailing. Experimental results indicate that the column-ring beam joint can transfer the moment and shear of the frame girder effectively by using reasonable reinforcing detail of the ring beam. Whether the final failure occurs in the end of frame girder or in the ring beam, all specimens have enough load carrying capacity and ductility. Increasing ratio of sectional height of the ring beam to that of longitudinal beam leads to concrete crash zone shifts from the lower part of the diagonal crack of ring beam to the lower part of the longitudinal beam, resulting in realistic failure mode of flexural hinges at beam ends.