十字形与T形圆钢管节点平面内受弯抗震性能对比

COMPARISON OF IN-PLANE FLEXURAL SEISMIC BEHAVIOR BETWEEN CHS CROSS-TYPE JOINTS AND CHS T-JOINTS

  • 摘要: 规范认为T形和十字形圆钢管节点的平面内抗弯承载力相同,但两类节点的受力特性不同。为了全面对比T形节点和十字形节点的平面内受弯性能,进行了6个节点(4个十字形和2个T形)平面内往复弯矩加载试验,并进行了受力机理分析和有限元分析,其中十字形节点进行了两侧支管同向受弯、反向受弯两种加载模式。结果表明:所有节点均为节点域主管管壁延性撕裂破坏,表现出较好的抗震性能;增加支主管直径比β能明显提高节点的抗弯承载力、延性、耗能能力;T形节点的抗弯承载力高于十字形节点,但延性不如十字形节点,T形节点的耗能能力介于十字形节点在两种加载模式下的耗能能力之间;对比反向受弯加载,同向受弯加载对β较小(接近及小于0.7)十字形节点的性能(耗能、延性和承载力)不利,但对β较大(接近及大于0.9)十字形节点的性能有利。

     

    Abstract: Current codes believe that the in-plane flexural strength of T-joints with unstiffened circular hollow sections (CHS) is the same as that of cross-type joints with corresponding CHS. However, the force characteristics of the former is different from the later. In order to comprehensively compare the behavior of the cross-type joints and the T-joints under in-plane bending (IPB) conditions, the experimental test of six CHS joints (four cross-type joints and two T-joints) under cyclic IPB conditions are carried out, and force mechanism analysis and finite element analysis are also carried out. The four cross-type joints stay in two loading conditions, which including a reverse bending loading condition and a syntropy bending loading condition. The results show that: the failure mode of each joint is the ductile tearing of the chord wall near the intersection, and all joints exhibit good seismic performances. Regardless of the T-joints or the cross-type joints, increasing β (brace-to-chord diameter ratio) can significantly improve its strength, ductility and, energy dissipation capacity. Comparing T-joints and the corresponding cross-type joints, the former has higher flexural strength than the latter, but its ductility is not as good as the latter, and its energy dissipation capacity is between the energy dissipation capacities of the cross-type joints under two IPB loading conditions. Contrast with the reverse bending loading condition, the syntropy bending loading condition is detrimental to the in-plane flexural behavior (e.g., strength, energy dissipation and ductility) of the cross-type joints with smaller β (close to and less than 0.7), but the syntropy bending loading condition is beneficial to the behavior of cross-type joints with a larger β (close to and larger than 0.9).

     

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