Probability of Collapse of Steel Frame Structures Subjected to Fire Hazard

The issue of fire scenarios approach to fire protection is often the subject of ongoing dis- cussions within the fire safety engineering community. The choice of an adequate number and type of fire scenarios is not always univocal and straightforward. Even if significant large-scale fire tests and sophisticated numerical simulation have been carried out to define the fire scenarios to be used in structural assessment, the definition of fire scenarios remains difficult, since several variables needs to be considered. For this reason it seems appropriate to introduce statistical tools to assess the most probable fire scenario s. Recently the authors proposed a probabilistic methodology integrating the MonteCarlo simulation with plastic limit analysis to assess the probability of collapse of a structure subjected to fire. The pro- cedure, finalized to identify the most onerous fire scenarios for the structural response, was already illustrated by means of a case study represented by a steel frame structure. Prelimi- nary results of some analyses showed the capability of the methodology, beyond the limita- tions related to the simplified assumptions. In this paper the results are briefly summarized whereas some simplified assumptions of the procedure are refined to comply with sugges- tions provided by Eurocodes. In particular relationships to define both the space-time evo- lution of the fire action and the response of materials and structural members are intro- duced.