新型叠合柱-混凝土梁中节点受力性能研究

Study on Mechanical Behavior of New Type Middle Joint of CFST Composite Column-Concrete Beam

针对现行设计规程中钢管混凝土叠合柱-混凝土梁连接方法中的不足,提出一种柱内设置钢管外环形钢筋的新型梁柱节点。梁端纵筋以卡扣(■型)、弯折(L■型以及型)的形式连接柱中环筋,利用柱中环筋平衡混凝土框架梁端纵筋传来拉力。制作5个钢管混凝土叠合柱-混凝土梁中间节点试件,进行梁端单调静力加载试验,研究节点试件的裂缝发展及分布、破坏形态、承载力、延性与钢筋应变发展规律;利用ABAQUS软件进行仿真模拟分析。结果表明:不同节点构造形式的试件最终破坏形态相同,均为梁根部弯曲破坏,试件均具有良好的延性和变形能力;梁受拉纵筋均能在试件达到屈服前屈服;试验过程中未出现梁纵筋和柱中环筋发生滑移脱落的现象。仿真模拟分析结果与试验结果基本吻合。

In view of defects in the connection of concrete-filled steel tubular(CFST) composite column to concrete beam joint specified in the current code, this paper proposed a new type of fastener anchorage connection of beam to column joint with ring reinforcement in the column. The longitudinal reinforcement of the beam end of the concrete frame connected ring bar in column in forms of ■type, L-type and ■type and the ring bar set outside the steel pipe in the column was used to balance the tensile force from the beam end. Five specimens of concrete-filled steel tubular composite column concrete beam joints were designed for the monotonic static loading tests. The distribution and development of cracks, deformation, failure mode, bearing capacity, ductility of the middle joints and rebar strain development law were studied, and simulation analysis was performed using the ABAQUS software. The results show that ultimate failure modes of specimens with different joint anchorage are similar: the bending failure occurs at the end of beam, and all specimens possess good ductility and deformation ability. The yield of ring bars in columns lags behind the yield of longitudinal bars under tension, and no longitudinal bar slips off central bars during the test. The simulation results are consistent with the test results.