Structural behaviour and design of high strength steel RHS X-joints

Design of chord sidewall failure in RHS joints using steel grades up to S960

“…Kuhn et al [21] and Wardenier [22], among others, proposed modifications to the codified design method in order to reduce the conservatism and scatter of the resistance predictions. Other analytical models were also proposed for chord sidewall failure, e.g., the four-hinge yield line model in combination with a reduced chord sidewall buckling length proposed by Yu [19], and the plate buckling models proposed by Becque and Cheng [20] and Lan et al [23][24]. Two alternative design methods, i.e., a modified bearing-buckling method and a so-called "Lan-Kuhn method" are proposed herein.…”

“…Apart from using the reduced chord sidewall slenderness (0.5) for RHS joints that are sufficiently restrained against out-of-plane movements, Wardenier [22] proposed to reconsider the effect of brace-to-chord height ratio (*=h1/h0). This is because the numerical results of Yu [19] and Lan et al [23][24] show that full-width RHS X and T joints with higher * and 2γ* (=h0/t0) ratios have a more-abrupt chord sidewall failure mode, i.e., the loaddeformation curve exhibits a sharp drop in load after the peak load. Thus, it would be logical to increase at least the safety margin for RHS joints with a less-ductile failure mode.…”

“…The restraint from the chord face and the brace to the chord sidewall is stronger than that of a pinned-end boundary condition, but weaker than that of fixed edges. Lan et al [23] proposed an analytical model of plate buckling for chord sidewall failure in RHS-to-RHS X joints which can properly consider the restraint and utilize the strain hardening of steel materials by using the continuous strength method. Later, Lan et al [24] simplified the resistance equations without considering the strain hardening for RHS-to-RHS X and T joints to reduce the computational effort.…”

“…The elastic buckling stress equation proposed for RHS-to-RHS T and X joints with θ1=90°, which can properly consider the restraint from the chord face and the brace to the chord sidewall, is as follows [23][24]:…”

“…Lan et al [23][24] developed an analytical model for plate buckling to properly consider the beneficial restraint of the chord face and brace for the chord sidewall in RHS-to-RHS X and T joints. Comprehensive assessment of the design methods remains limited, and more suitable design rules for chord sidewall failure in RHS joints are needed.…”