Structural fire analysis of simple steel structures by using LS-DYNA explicit solver

When design steel structures, structural fire safety design is equally important as loading-bearing design. Currently, structural fire design is moving from prescriptive approach to performance-based approach. One of the key essential techniques for performance-based approach is the numerical analysis technique of steel structures in fire using advanced calculation models. In this paper, the structural fire analysis procedure from 2D temperature analysis to structural response using Ls-Dyna was developed and validated by the fire tests of a simply supported beam, a simple steel frame and a both axially and rotationally restrained steel column. 2D implicit temperature analysis is efficient in these cases and sufficient accuracy was achieved. Using explicit solver, structural response in fire can be simulated up to collapse with the considerations of the temperature-dependent material non-linearity and possible contacts in joints. Both beam element models and shell element models were developed and the structural responses were compared with the fire tests from literature. Results show that the developed modeling techniques using Ls-Dyna explicit solver can effectively capture the key behavior of steel structures in fires. These key behavior includes deformation responses of beam and column, axial forces developed due to restraints and fire resistance time.