3D TEMPERATURE FIELDS IN SHOT-NAILED COLD-FORMED STEEL SHEETING JOINTS

摘要

Powder-actuated shot-nail connection is widely used in connecting the cold-formed steel sheeting to its supporting members in roof structures. In fire, the catenary action is developed in roof sheeting at large deformation. The tensile forces at supports are sustained by the connectors. The temperature in proximity of fasteners under fire is a critical parameter of the load carrying resistance of the roof sheeting systems. In this paper, 3D temperature fields in the proximity of connections are studied numerically when the structure and connections are protected by intumescent paint and rockwool panels for the following five cases: Case 1 neither steel sheeting nor its support is fire protected; Case 2 only the support member is protected by lmm-thick intumescent paint; Case 3 both support member and part of steel sheet near the connectors is protected by the intumescent paint; Case 4 steel sheeting is protected by rockwool panels and chord is protected by the intumescent paint; Case 5 both steel sheeting and chord are protected by rockwool panels. Numerical model and parameters used in the model are briefly introduced. The simplified representation of intumescent paint is described. Parametric analyses are performed in order to investigate the sensitivity of the parameters of thermal contacts. The approximate cavity radiation method in ABAQUS is used to take the cavity radiation into account among the surfaces of the profiled steel sheeting and fire protection panel. The 3D temperature fields in the proximity of shot-nail connections from above mentioned fire protection solutions are compared. The benefits of using various fire protection solutions are discussed.