Static strength variation of thick-walled CHS X-joints with different included angles and chord stress levels

摘要

This paper reports the results of numerical study on thick-walled circular hollow section (CHS) joints with inclined braces, including the axial chord stress effects on static joint strengths. Four brace inclination angles θ, varying from 30° to 90°, and three brace-to-chord diameter ratios β are considered. It was found that the sin θ term, frequently used in current design recommendation, is insufficient to account for the θ effect. Thin-walled and thick-walled joints exhibit different trends with respect to θ due to different stiffness of the chord wall which affects the stress distribution around the brace-chord intersection. The brace inclination angle is found to influence the load-transfer mechanism in the joint and consequently the interaction between the braces loads and chord stresses. A new chord stress function is proposed in this paper, with the geometric parameters θ and β incorporated, which shows good agreement with the present finite element results.