（1 中南林业科技大学土木工程学院， 长沙 410004; 2 湖南大学土木工程学院钢结构研究所， 长沙 410082）

［摘要］为研究主管轴力对N形主方支圆钢管搭接节点受力性能的影响，设计制作了2组共4个节点试件进行极限承载力试验。试验结果表明：当节点几何参数、构造及支管受力性质相同时，主管所受轴压力较大的节点，其承载力低于主管轴压力较小的节点。以试验为基础，建立了考虑主管轴力影响的节点有限元分析模型，计算得到了主管轴力对该类节点承载力的影响参数，将其与按《钢结构设计标准》（GB 50017—2017）中圆管节点及矩形管节点主管轴力对节点承载力影响的参数公式计算结果进行了对比。研究表明：主管轴拉力对N形主方支圆钢管搭接节点的承载力影响较小，可以忽略，但主管轴压力对节点承载力影响较大，且规范参数公式对该类节点并不适用。通过回归分析，提出了主管轴力对N形主方支圆钢管搭接节点承载力影响参数的建议公式，为该类节点承载力计算提供参考。

［关键词］N形主方支圆钢管搭接节点； 承载力； 主管轴力； 影响参数； 建议公式

中图分类号：TU391-3文献标识码：A文章编号：1002-848X(2018)22-0007-08

Study on influence of chord axial force on bearing capacity of overlapped N-joints with square chord and circular braces

Yuan Zhishen1， Shu Xingping2， Hu Xibing1

（1 College of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China;2 Steel Structural Institute of Civil Engineering College, Hunan University, Changsha 410082, China）

Abstract:To study the influence of chord axial force on bearing capacity of overlapped N-joints with square chord and circular braces, four specimens in two groups were tested under monotonic loading. The test results show that when the geometric parameters, the details of joints and the nature of brace force are the same, the bearing capacity is lower with higher chord axial compression than that with lower chord axial compression. Based on the experiment, nonlinear finite element analysis models considering the chord axial force were established, and the influence parameters of the chord axial force were obtained. Meanwhile, a comparison was carried out between the FEA results and the results by design equations of circular hollow section and rectangular hollow section  joints in  Standard for design of steel structures(GB 50017—2017). The research indicates that the chord axial tension has little effect on the bearing capacity of N-joints with square chord and circular braces, but the chord axial compression has obvious effect on the bearing capacity of this joint. However, it reveals that the design equations of influence parameter of the chord axial force for CHS or RHS joints are not suitable for N-joints with square chord and circular braces. By applying multivariate regression analysis, a formula of influence parameter of the chord axial force for N-joints with square chord and circular braces is proposed, which provides the reference for the calculation of bearing capacity of this joints.

Keywords:overlapped N-joints with square chord and circular braces; bearing capacity; chord axial force; influence parameter; proposed formula

*国家自然科学基金项目（51608544），湖南省教育厅优秀青年基金（14B187），中南林业科技大学引进高层次人才科研启动基金（2013RJ013）。

作者简介：袁智深，博士，讲师，Email：36894743@qq.com。