Stress concentration factors for RHS-to-RHS X-connections near an open chord end

Abstract

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.