矩形钢管和矩形钢管混凝土T形不等宽受拉节点轴向刚度

为获得T形节点轴向刚度简化计算公式,根据节点受力特点,提出了适用于矩形钢管节点的平面框架模型和适用于矩形钢管混凝土节点的固端梁模型,并推导得到了2类节点的节点轴向刚度理论公式; 运用有限元方法对节点轴向刚度理论公式中的节点域有效长度l_eff进行参数分析,拟合得到l_eff简化计算公式; 将节点轴向刚度理论公式与试验及有限元结果进行了对比,并分析了主管内填混凝土对节点轴向刚度的影响。结果表明:主管高宽比和主管宽厚比对l_eff的影响较小,不予考虑; l_eff与主管宽度和支管高宽比均呈线性关系,且随之增大而增大; l_eff与支主管宽度比β呈非线性关系,且随之增大而减小; 2类节点的轴向刚度理论公式计算结果与试验结果及有限元结果均吻合较好; 主管内填混凝土可以提高节点轴向刚度,提高系数k_c/h随着主管高宽比的增大而增大,随着β的增大呈现先增大后减小的规律,且当β=0.6～0.7时提高最大。

Axial Stiffness of RHS and CFRHS T-joints with Unequal Width Subjected to Tension

In order to obtain the simplified calculation formula of the axial stiffness of the T-joint, a plane frame calculation model suitable for the rectangular hollow section(RHS)joints and a fixed end beam model for concrete-filled rectangular hollow section(CFRHS)joints were proposed according to the characteristics of the joint force. Then the theoretical formula of the joint axial stiffness of the two joints types was derived. The finite element method was used to analyze the joint domain effective length l_eff in joint axial stiffness formula, and the simplified formula of l_eff was obtained by fitting. The theoretical formula of the joint axial stiffness was compared to the experimental and finite element model(FEM)results, then the influence of the concrete filled in the chord on the joint axial stiffness was analyzed. The results show that heigh-width ratio and width-to-thickness ratio of chord have little effect on l_eff and can be neglected. l_eff has a linear relationship with width of chord and height-width ratio of brace, and increases with them. The effective length l_eff has a nonlinear relationship with width ratio of brace and chord β, and decreases when β increases. The axial stiffness calculation formula of the two joints types agree well with the experimental and FEM results. The concrete filled in the chord can increase the joint axial stiffness, and the increase coefficient k_c/h increases with the increase of height-width ratio of chord. Moreover, k_c/h increases first and then decreases with the increase of β, and the maximum value occurs when β=0.6-0.7.