考虑节点刚度的圆钢管混凝土桁架受压腹杆计算长度分析

摘要

The effects of various factors on the joint rigidity of concrete⁃filled circular hollow section ( CFCHS ) joints were analyzed and compared with those of circular hollow section ( CHS) joints. To determine the coefficient of the effective length of a compressed brace that is influenced by joint rigidity in a concrete⁃filled circular steel tube truss, T/Y CHS⁃CFCHS joint specimens with different geometry parameters under in⁃plane bending moment were investigated. The formula of the joint rigidity of CHS⁃CFCHS joints and the coefficient of the effective length of the compressed brace were established based on geometry parameters of the joints. Results show that the joint rigidity of CHS⁃CFCHS joints increase accordingly compared to CHS joints. Joint rigidity depends on the chord stiffness and brace⁃to⁃chord contact area;joint rigidity decreases as the value ofγorθincreases and increases as the value ofβorτincreases. The computation length of the compressed brace may be conservative if the computation is performed according to the design code for steel structure; the effective length of the brace can be considered as 0.7l in the CHS⁃brace to CFCHS⁃chord truss.%为考虑节点刚度对钢管混凝土桁架中受压腹杆计算长度的影响，对圆钢管混凝土T／Y型节点在平面内弯矩作用下的抗弯刚度进行了数值研究，比较了空钢管节点和内填充混凝土钢管节点的抗弯刚度的差异，建立了钢管混凝土节点的抗弯刚度参数计算公式，给出了考虑节点刚度的受压腹杆的计算长度。研究表明：空钢管节点的弦杆内填充混凝土后，节点的抗弯刚度有明显的提高，节点刚度取决于弦杆的径向刚度和弦杆、腹杆相贯面的表面积；节点刚度随β、τ的增大而提高，随γ、θ的增大而降低；受压钢管腹杆的计算长度沿用《钢结构设计规范》可能偏于保守；对于上、下弦杆均为圆钢管混凝土杆件的桁架，受压腹杆的计算长度可近似的取0．7l。