Lapped cold-formed steel Z-shaped purlin connections with vertical slotted holes

• 42 CFS Z-shape lapped purlins with vertical slotted connection were tested.
• Flexural strength and stiffness of the lapped purlin were investigated.
• The parameters that influence the behavior of the lapped purlin were studied.
• Design recommendations for the lapped purlins were proposed.

In current construction practice, vertical slotted holes are widely used in the lapped joints of cold-formed steel (CFS) Z-shaped purlins to simplify the erection of multi-span purlin systems by providing extra installation tolerance. However, almost no research has been conducted on the performance of CFS Z-purlin lapped joints with vertical slotted holes. Presented in this paper is an experimental study on the structural behavior of lapped CFS Z-shaped purlin connections with vertical slotted holes. A total of 42 flexural tests were performed on lapped CFS Z-shaped purlins with different lap lengths, purlin depths, thicknesses and spans. The results indicate that the flexural strength and stiffness of the lapped purlins are primarily influenced by four parameters, i.e., the ratio of lap length to purlin depth, the ratio of lap length to purlin thickness, the ratio of purlin depth to purlin thickness, and the ratio of lap length to span. Based on the test results, design recommendations for evaluating the moment resistance and flexural stiffness of lapped CFS Z-shaped purlins with vertical slotted holes are proposed.