平面X形矩形钢管相贯节点平面外抗弯刚度

Rigidity of unstiffened X-type RHS joints subjected to out-of-plane bending

为了获得平面X形矩形钢管相贯节点的平面外抗弯刚度计算式,基于节点局部变形特征,借鉴塑性铰线模型,建立了6杆系模型并导出节点刚度理论计算式。为了弥补6杆系模型无法反映主管上、下翼缘对节点抗弯刚度影响的不足,建立了矩形环模型并导出相应的节点刚度理论计算式。综合两个模型,结合参数分析结果对理论计算式进行改进。通过多元回归分析,获得X形矩形节点平面外抗弯刚度参数化计算式。研究结果表明:节点刚度与主管壁厚的三次方成正比,与主管截面宽高比呈线性关系,与支主管截面高度比、支管截面宽度与主管截面高度比呈较复杂且相互影响的关系;支主管截面高度比对节点刚度的影响较大,支主管壁厚比对节点刚度的影响较小;参数化计算式所得刚度值与有限元结果相差大部分小于10%。

In order to establish a precise and practical parameterization calculation formula for the rigidity of unstiffened X-type RHS joints subjected to out-of-plane bending, a six-beam model for X-type joints rigidity was developed based on the local deformation behavior and yield line model of the joints subjected to out-of-plane bending, and a theoretical formula for the bending rigidity was established. In order to remedy the defect that the six-beam model can't reflect the influence of chord flange on the bending rigidity of the joint, a rectangular ring model was introduced and the corresponding theoretical formula for the bending rigidity was established. The final theory formula for bending rigidity was established by integrating the above two formulas, and improved in the light of the parametric analysis result from FEA. As a result, a practical parameterization formula for the out-of-plane bending rigidity of an X-type RHS joints was obtained through multi-variable nonlinear regression analyses. The results show that the bending rigidity is directly proportional to the third power of the chord thickness. The bending rigidity also has a linear relationship with the ratio of width to depth of the chord section. There is a more complex relation of function between the bending rigidity (the dependent variables) and the branch-to-chord depth ratio, the ratio of branch width to chord depth, and the two independent variables also influence each other. The branch-to-chord depth ratio has significant effects on the bending rigidity, while the branch-to-chord thickness ratio has less impact on the bending rigidity. The relative errors between bending rigidity values obtained by the parameterization formula and the FEA results are mostly less than 10%. © 2016, Editorial Office of Journal of Building Structures. All right reserved.