T形截面多腔式钢管混凝土柱-U形截面钢混凝土组合梁竖向肋板式框架节点抗震性能研究

Seismic behavior of T-shaped multi-cell CFST column to U-shaped steel-concrete composite beam joint

为解决外环板外露和内环板影响混凝土浇筑的问题,在钢管混凝土异形柱和U形截面钢混凝土组合梁框架结构中增加竖向肋板节点构造,对6个缩尺比为1∶2的T形截面多腔式钢管混凝土柱-U形截面钢混凝土组合梁节点试件进行低周往复试验,得到了试件的破坏模式、荷载-位移滞回曲线以及弯矩-转角曲线,分析了节点核心区剪切变形、延性、耗能能力和应力分布规律。试验研究表明,竖向肋板节点的破坏模式为梁端塑性铰破坏,滞回曲线较为饱满,耗能能力良好,满足欧洲EN 1993-1-8中对于无支撑框架刚性节点的要求。建立了钢管混凝土异形柱与U形截面钢混凝土组合梁节点的精细化有限元模型,该模型对节点荷载-位移曲线以及关键部位的破坏形态均能较为准确地预测,并在此基础上进行了节点承载力及节点刚度参数分析,分析结果表明提高U形钢板厚度能明显提高节点承载力。为保证竖向肋板连接节点达到刚性节点要求,建议竖向肋板翼缘外高度、翼缘内高度、肋板厚度以及肋板与梁翼缘间连接长度分别不应小于U形钢梁宽度的60%、20%、100%以及150%。

In order to address the problem that the exterior diaphragms will interfere to an indoor space and interior diaphragms will affect the concrete pouring,a novel vertical stiffener joint detail in special-shaped concrete-filled steel tubular(CFST)column and U-shaped steel-concrete composite beam structures was proposed.Six half-scaled specimens of T-shaped multi-cell CFST column to U-shaped steel-concrete composite beam joint were tested under cyclic loading.The failure mode,load-displacement hysteretic curves and moment-rotation curves of the specimens were obtained.The joint shear deformation,ductility,energy dissipation capacity,and stress distribution were analyzed.The test results demonstrate that the joint with vertical stiffeners presents plastic hinge failure at the beam end,exhibits full hysteresis curves as well good energy dissipation capacity,and meets the requirements of EN 1993-1-8 for rigid joints in a braced frame.A refined finite element(FE)model of the proposed joint was established,where the load-displacement curves and the failure mode agreed well with the experimental results.Based on the FE model,a parametric analysis on the joint strength as well the joint stiffness was conducted.The numerical results show that increasing the U-section steel thickness can significantly improve the joint strength.To meet the rigid joint requirements of vertical stiffener joints,it is suggested that the outer height of the vertical stiffener,the inner height,the thickness,and the connection length between the vertical stiffener and the beam flange should not be less than 60%,20%,100%and 150%of the beam flange width,respectively.