Abstract:
The current study investigates the fire resistance of the steel roof structure for a typical warehouse using the performance-based approach. Various fire scenarios are simulated using the Fire Dynamics Simulator (FDS) program. The simulation considers the location of the ignition source, the fuel type and the clearance height of the warehouse as the varying parameters. For each of the modeled fire scenarios, the behavior of the roof structure is examined using nonlinear structural analysis, taking into account the varying properties of steel under fire, with and without fire protection. Based on the fire modeling results, it is found that the fuel types significantly affect the behavior of the modeled fire in terms of the fire growth and the spread of flames. The plastic storage contents result in a rapid fire growth due to the significant feedback of heat from the flames. The wood storage contents result in a considerably slower fire growth that occurs through direct radiation from the flames to nearby objects. It is observed that the failure of the roof structure is due to three key factors: the increasing axial compression; the significant drop of the mechanical properties of steel; and the P-[Delta] effects. For the cases of plastic storage contents, the time to failure is in the range of 1100-1500 seconds and 330-400 seconds for the roof structure with and without fire protection, respectively. For the cases of the wood storage contents, the minimum time to failure is 1750 seconds for the roof structure without fire protection and the maximum time to failure is longer than 7200 seconds (the maximum burning time) when the roof structure is fire-protected. The outcome of the current study can be used to assess the safe egress time for the structure under consideration, to establish a guideline for proper design of the fire protection systems, as well as to set an initial step towards the fire risk assessment of similar structures in accordance with the national fire safety regulations.
