Finite Element Modeling of Single Lap Shear Screw Connection in Steel Sheeting in Fire

Abstract

The load bearing steel deck is used in insulated metal deck roofing system for industrial buildings with lowpitched roof areas. The steel sheeting sections are manufactured with cold forming from thin steel strip and are attached to the underlying purlins or more commonly straight to the steel trusses by self-drilling or self-tapping screws. The behavior of sheeting connections is important in fire especially when the sheeting is in catenary action and tensile forces are developed at supports where the screw connectors are located. A 3D finite element model is created using ABAQUS software to simulate the single lap screw connections connecting thinner sheet (0.8 mm) to thicker sheet (10 mm) under static shear at both room and high temperatures. This model considers the material nonlinearity, large deformation and contact behavior. The connection model is analyzed through the elastic and plastic ranges up to failure. The analysis reveals that the failure modes of the connection for both room and elevated temperatures are bearing failure of the thinner sheet. The load bearing capacity of the connections depends on the friction between the washer and the thinner sheet, the direct bearing of the screw shank against the thinner sheet and the postbuckling resistance of thinner sheet. Degradation of material at elevated temperature further reduces the strength and stiffness of the connections. This connection model can be taken as a component model in the analysis of the behavior of steel sheeting system in fire, which is highly non-linear so as to save the computing time.