Previous records of fire and blast incidents have shown the extensive damage that these actions can cause in building structures in general and steel buildings in particular. Therefore, it is crucial that strategic facilities are designed to withstand these extreme loads with as little damage as possible. However, the design of structures to resist blast and fire actions has typically been carried out prescriptively and without consideration for the uneven distribution of temperatures in large building compartments typical of today’s architectural practice. Blast pressures due to explosions are also likely to be followed by travelling fires in these compartments. Moreover, due to the significant level of uncertainty involved, a performance-based framework is likely to be more suited for the design and assessment of structures subjected to these loads. This thesis aims to investigate the structural performance of steel structures under travelling fires as well as multi-hazard conditions involving blast and travelling fires from a performance-based perspective.
Non-linear finite element analyses are carried out on steel frames considering various travelling fires and post-blast travelling fire scenarios. The PEER performance-based framework, originally developed for seismic actions, is tailored and used to assess the building performance under these actions. The results show that the structural response could be underestimated or overestimated by up to 30 % when there is significant correlation between the maximum compartment temperature and the length of travelling fire for very low probabilities of exceedance. Under post-blast travelling fires, the first storey is likely to be the most critical storey, and blast and fire parameters can significantly affect the structural response. Moreover, correlation effects between maximum compartment temperature and blast overpressure are found to be more significant when low exceedance rates are considered.
The results of this research demonstrate that a performance-based assessment can be used to examine the response of steel structures under these extreme loads and to assess the efficiency of different structural systems. It can also potentially lead to great savings in the cost of blast and fire protection required.