Analysis and design of lapped connections between cold-formed steel Z sections

This paper presents an analysis and design method for lapped connections between cold-formed steel Z sections after careful calibration against test data obtained from a total of 26 one point-load tests on lapped connections. Based on the experimental observations on the lapped connection tests where combined bending and shear is always critical in the cross-sections at the end of laps, an analysis method is proposed to evaluate all the internal forces within the lapped connections. Once the co-existing moments and shear forces in the lapped connections are evaluated, the critical sections are readily checked against combined bending and shear using codified design rules. Moreover, design expressions are also proposed for the evaluation of effective flexural rigidities of lapped connections with various bolt configurations against practical lap length to section depth ratios. Consequently, the structural behaviour of lapped sections between cold-formed steel Z sections in terms of strength and stiffness is quantified rationally for general design. The research project aims to provide understanding to the structural performance of lapped connections between cold-formed steel Z sections, and hence, to develop a set of rational design rules for multi-span purlin systems with overlaps in modern roof construction.