Chord-end RHS-to-RHS and CHS-to-CHS X-connections with rigid cap plates: Stress concentration factors

Abstract

For rectangular hollow section (RHS)-to-RHS and circular hollow section (CHS)-to-CHS connections situated near a truss/girder end, reinforcement using a chord-end cap plate is common; however, for fatigue design, formulae in current design guidelines [for calculation of stress concentration factors (SCFs)] cater to: (i) unreinforced connections, with (ii) sufficient chord continuity beyond the connection on both sides. To develop definitive design guidelines for end connections with rigid cap plates, previous full-scale connection test results have been used to validate a finite element (FE) modelling approach, and a total of 496 FE models with different chord end distance-to-width (or diameter) (e/b0 or e/d0), branch-to-chord width (β), branch-to-chord thickness (τ), and chord slenderness (2γ) ratios have been modelled and analyzed. Existing SCF formulae in CIDECT Design Guide 8 are shown to be inaccurate if applied to cap plate-reinforced end connections. SCF correction factors (ψ), and parametric formulae to estimate ψ based on e/b0 (or e/d0), β, τ and 2γ, are derived.