Confiabilidade estrutural de vigas de madeira : comparação entre seções otimizadas e não otimizadas para situação de incêndio pelo método da seção reduzida

Abstract

The fire resistance of timber structures is directly related to the robustness of their structural elements. However, optimizing beam cross-sections can lead to a more efficient use of material without compromising safety. This optimization, however, affects structural reliability, making it necessary to quantify the residual safety of beams over the duration of fire exposure. In this context, this study investigates the structural reliability of optimized and non-optimized timber beams using probabilistic approaches. The analysis is carried out using Monte Carlo Simulation (MCS) and the First Order Reliability Method (FORM), considering beams exposed to fire and evaluated through the reduced cross-section method. The influence of material loss due to charring is incorporated into the model, enabling the estimation of residual strength over different fire exposure times. Beams with four faces exposed to fire were tested to analyze the impacts of structural optimization on failure probability. The results indicate that optimization can be a determining factor for structural safety in fire scenarios, as beams with greater crosssectional height exhibited lower failure probabilities. Furthermore, the modeling enabled quantification of the influence of varying fire exposure times on structural degradation. It is concluded that the integration of structural reliability and optimization contributes to the development of more efficient designs, allowing a balance between safety and material economy.