Estudo do fator de redução da resistência ao escoamento do aço de perfis U enrijecido em situação de incêndio

Abstract

This work presents a study on the resistance factor to the steel yield strength for cold formed profiles, U lipped section types, at elevated temperature. The strength reduction factor of steel for class 4 sections at elevated temperatures, k,, is used in the design resistance to normal forces of the cross-section to uniform compression at elevated temperature. It was analyzed, through numerical simulation by finite element method, the variation of the reduction factor as a function to the slenderness ratio associated with the failure mode. There was no significant observed variation of the reduction factor in relation to the local and distortional buckling mode failure. Thus, it was used only the profiles that failed for local buckling to establish an equation to the variation of the reduction factor as a function to the reduced slenderness ratio associated with local buckling and the ratio of the profile nominal dimensions of the flange and the web. The equation presented in this work presents a continue variation with reduced slenderness ratio associated with local buckling, unlike the standardized reduction factor that presents a discontinuity between the ky, and the k, values.