Test and design of stainless steel K-joints in cold-formed circular hollow sections

Abstract Stainless steel structures have obvious competitive advantages for buildings in the corrosive environment. In recent years, many studies have been conducted on the behaviors of stainless steel materials and members, but the behaviors of joint were rarely reported. This study carried out nine tests on stainless steel K-joints in cold-formed circular hollow sections. The material properties of circular hollow sections, the ultimate loads, the failure modes, and the load-deflection curves of joint were all reported. All the joints failed in the chord plastification. Finite element models were developed for K-joints, and were validated using the test data. Parametric studies were then conducted. Totally, 720 finite element models were built, and the effects of the geometric configuration, the chord preload, and the chord material properties on the joint capacity were explored. Based on the results of the parametric studies, the parameter Qu accounting for the influence of geometric configurations (i.e. β, γ, and g) and the parameter Qf accounting for the influence of chord preload were modified based on the corresponding formulae in the CIDECT design guide for low-carbon steel K-joints. To further improve the accuracy of prediction, a new parameter Qy400 was proposed to consider the effect of the chord material property variations. The predictions of the proposed were compared with test data collected in literature. It is concluded that the proposed design formulae have good performances in predicting the capacity of stainless steel K-joint in circular hollow section.