Improving deep steel deck roof diaphragm performance by adding end-lap panel strips

Roofing systems made of steel deck panels are widely used in North America for low-rise commercial and industrial building structures. Besides their gravity load-carrying role, these roofing systems can be used as a diaphragm to transfer the in-plane shear forces induced by wind and seismic loads to the structures' lateral force-resisting systems. Deep steel deck panels (depth greater than 76 mm) under in-plane shear loading are more susceptible to distortion and warping effects compared to shallower deck panels. This paper proposes a new method to increase the shear strength and stiffness of roof diaphragms by adding end-lap panel strips at both ends of the roof diaphragms on the corrugated edges. The extra stiffness provided by the end lap panel strips mitigates panel distortion and local buckling of the webs. The Métal Sartigan MS100 steel deck panel investigated in this research has a depth of 100 mm. The deck has web and flange stiffeners and is the first stiffened deep steel deck panel produced in Canada. Two large-scale diaphragm specimens were tested under monotonic quasi-static loading. The first specimen was a standard roof diaphragm, and the second specimen was identical to the first except for added end-lap panel strips at both corrugated ends. The test results showed that the added end-lap strip panels influenced the shear diaphragm strength and stiffness, resulting in a 35 percent increase in shear strength and a 39 percent increase in shear stiffness. The proposed strengthening/stiffening method could be effectively used in practice to improve the performance of building structures.