Avaliação global-local da vida em fadiga de uma junta soldada do vão de acesso da ponte de Alcácer do Sal

Abstract

Fatigue is one of the predominant limit state in the design of steel and composite structures under cyclic loading, such as railway bridges, highway bridges and viaducts. Fatigue occurs, preferably, in regions with geometric changes and stress concentrations, such as welded joints. For the evaluation of fatigue resistance, the most common approach employed is based on the maximum variation of the nominal stress. However, this methodology has a limited number of geometric details, related in specific codes for the design of structures. Recent studies have presented other approaches, such as the “Hot Spot Stress” (geometric stress) approach, which fatigue life of welded connections can be estimated based on numerical analysis by finite element method, through obtaining the stresses at a reduced number of points. The present work aims to evaluate the fatigue process through the submodeling dynamic analysis in a critical detail for fatigue using the “Hot Spot Stress” methodology. It is proposed to analyze the fatigue life using the local model of welded connections from the “Alcácer do Sal” city railway structure, in Portugal, considering the recommendations from IIW (2008) and Eurocode 19931-9 (2005). The submodeling analysis proved to be an important and effective tool for the fatigue evaluation in welded joints.