Towards Fragility Analysis for Concrete Buildings in Fire: Residual Capacity of Concrete Columns

Fire engineering a building, in general, has one central performance objective – life safety – and property protection is rarely explicitly considered. The engineering is typically based on only one possible fire, which may not represent the most onerous scenario (or may be much too onerous to be considered realistic). Taking inspiration from fragility analyses used in seismic engineering, this paper explores the relationship between post-fire structural response and the ‘ intensity’ of the fire. The influence of 27 different parametric fires on the residual capacity of a reinforced concrete column is theoretically assessed and it is shown that the ventilation factor used to define the fire curves has a clear influence on the calculated residual response of the column, both in terms of peak fire temperature but also total duration of fire exposure. This paper represents a first step towards developing quantified fragility analyses for probabilistic structural fire design of concrete buildings.