Aplicação de confiabilidade ao estudo de elementos de aço comprimidos em situação de incêndio

Abstract

The exposure of steel structural elements to high temperature fields induces changes in its mechanical properties, penalizing the bearing capacity of these elements. Currently, the design of steel structures in fire situation is treated by ABNT NBR 14323: 2013. The codes that deal to structural design are mostly based on deterministic or semi-probabilistic procedures, based on partial safety factors, not allowing an accurate assessment of limit states of structures. The reliability analysis applied to the structural design can assess the uncertainties associated to the problem, since variations in the mechanical and geometrical properties of the element to the intensity of load and probability of occurrence of extreme values through the structure lifetime. In this reliability-based framework, the probability of failure of the structure can be predicted still in the design stage. In this context, design variables are described as random variables, within the choice of an adequate distribution model to represent statistical data. This work aims to develop a study on the safety levels associated with the design of compressed steel columns exposed to fire, according to the Brazilian code, in order to verify its applicability face to the related literature recommendations. It is also presented an alternative design procedure based on the search of a target reliability index.