Random parameters and sources of uncertainty in practical fire safety assessment of steel building structures

Abstract

The purpose of this article is to identify sources of uncertainty and outline the basis of probabilistic safety assessment of steel structures exposed to fire conditions. Awareness of the existence of unavoidable uncertainties and non-deterministic nature of many phenomena and parameters may be essential for a proper understanding of the issues of structural reliability in the event of extreme or accidental actions. The study highlights various sources of uncertainty associated with practical fire safety assessment of steel structures which significantly affects the reliability of estimates. Universal factors influencing random structural resistance in all design conditions were separately described. A significant part of the paper is devoted to issues that relate only to an accidental design situation of fire. Reference was made to the uncertainty of the analytical model describing the bearing capacity of the structure in terms of probabilistic approach. A synthetic summary on the impact of the method of carrying out material testing in elevated temperatures on the strength parameters, was made. In the conclusion it has been underlined that, inter alia, due to the lack of relevant statistical data, conducting a fully reliable probabilistic analysis of random structural resistance under fire is currently not possible. A unique part of the paper contains the proposed model of probability-based analytical approach to assess random structural resistance in fire conditions, incorporating an authorial modification to models used for standard conditions.