Numerical Studies on Fire Performances of the Joints in Steel Staggered-Truss Framing System

The structural behaviors of a sub-truss, typically used in a steel staggered-truss framing system (SSTFS), under fire conditions was studied comparatively using the finite element method with the solid element and beam element respectively. Both the internal force of structural members and the mechanical response behavior of joints at elevated temperature were investigated. And the reasonable computational simplification way for joint was explored. The results indicate that: the joint plays an important role in the fire resistant performance of SSTFS. The gusset plate is easily destroyed at high temperature and its fire protection should be enhanced relatively. Comparative with the result of solid element, it suggests that the hinged joint could simulate the connection of web members better than rigid joint. As to the simulation method of structural members, some obvious deviations were found between the beam element and solid element in fire resistance analysis as whether the gusset plate is considered. Fortunately, the internal force of components and the structural deformation could be simulated well using the beam element and it can save lots of computing resource and time. Hence, while the gusset plate is protected well, the beam element for structural members with hinged joint for connection could be used for the preliminary estimate.