Reliability of a timber structure exposed to fire: estimation using fragility function

Abstract

Natural fires occurring in buildings and damage to structures caused by these fires have always been uncertain phenomena. Failure of a structure exposed to a natural fire can not be predicted with certainty. The present paper de-scribes an approach to an estimation of failure probability by developing a fragility function for a timber structure exposed to the hazard of fire. The fragility function is used to relate results of a probabilistic computer simulation of a potential fire to the probability that an exposed structure will fail during this fire. The developing of the fragility function utilizes the fact that fire damage to an unprotected timber structure can be expressed through the depth of char front. This depth is used as a key demand variable of the fragility function. The estimate of the failure probability is calculated as a mean of fragility function values.