Fragility Analysis of a Steel Building in Fire

Community resilience to extreme events is an issue of increasing concern in our interconnected and urbanized societies. This work provides a framework to evaluate the response of a community of buildings to fire following earthquake, a potentially highly destructive cascading multi-hazard event. In a previous part of the work, a model has been developed to predict the probability of ignition in a building due to an earthquake. Given an ignition in a building, the probability of the structure exceeding certain limit states must be evaluated in order to quantify the expected damage loss. Adopting an approach similar to that used in seismic engineering, fragility functions can be developed for structures subjected to fire. The methodology is described here for a prototype nine-story steel frame building. In developing the fragility functions, uncertainties in the fire model, the heat transfer model and the thermo-mechanical response are considered. In addition several fire scenarios at different locations in the building are studied. The demand on and capacity of the system are assessed probabilistically in terms of critical temperature. The developed fire fragility functions yield the probability of exceedance of predefined damage states as a function of the fire load in the building. Future works will aim to implement fire fragility functions into a GIS based risk assessment software platform for assessment of the expected risk and cost associated with fire following earthquake for a community of buildings.