This paper presents an experimental and finite-element (FE) study to determine stress concentration factors (SCFs) for directly welded rectangular hollow section (RHS)-to-RHS axially loaded X-connections near an open chord end. Two-hundred and fifty-six FE models of RHS-to-RHS X-connections, with varied chord end distance-to-width (e/b₀), branch-to-chord width (β), branch-to-chord thickness (τ), and chord slenderness (2γ) ratios were modelled and analyzed by using commercial software. The analysis was performed under quasi-static axial compression force(s) applied to the branch(es) and validated by comparison of strain concentration factors (SCNFs) to SCNFs obtained from two large-scale experimental tests. For all 256 connections, SCFs were determined at five critical hot spots on the side of the connection near the open chord end. The SCFs were found to vary as a function of e/b₀, 2γ and β. Existing formulae in CIDECT DG8 to predict SCFs in directly welded RHS-to-RHS axially loaded X-connections are shown to be conservative when applied to a connection near an open chord end. SCF reduction factors (ψ), and a parametric formula to estimate ψ based on e/b₀, 2γ and β, are derived.

本文提出了一项实验和有限元（FE）研究，以确定在靠近弦末端的直焊矩形空心截面（RHS）到RHS轴向载荷X形连接的应力集中因子（SCF）。RHS到RHS X连接的256个有限元模型，弦末端到宽度的距离（e / b ₀），分支到和弦的宽度（β），分支到和弦的变化厚度（τ）和弦长（2γ使用商业软件对比率进行建模和分析。该分析是在施加到分支上的准静态轴向压缩力下进行的，并通过将应变集中因子（SCNF）与从两次大规模实验测试中获得的SCNF进行比较进行了验证。对于所有256个连接，在靠近弦开放端的连接侧的五个临界热点处确定SCF。所述SCFS发现的一个函数而变化È / b ₀，2 γ和β。当将CIDECT DG8中用于预测直接焊接的RHS-to-RHS轴向载荷X型连接中的SCF时，现有公式显示为保守的公式，适用于靠近开放弦端的连接。SCF折减系数（ψ），以及一个参数公式来估计ψ基于é / b ₀，2 γ和β，导出。