Fatigue assessment of a complex welded steel bridge connection utilizing a three-dimensional multi-scale finite element model and hotspot stress method

摘要

Some novel complex structural components of steel bridges are not explicitly addressed in the existing fatigue design codes and require an alternative local fatigue assessment method. This paper proposes a fatigue assessment protocol for these complex critical components of steel bridges, using the hotspot stress method. A computationally efficient finite element model of a large-scale bridge is created to provide the local structural response of complex components, under simulated dynamic traffic loads. A multi-scale model is implemented to accommodate higher dimension elements, which are recommended for fatigue assessment via hotspot stress method. The multi-scale model is created for the case study, the Memorial Bridge in Portsmouth, NH, which is a vertical lift steel truss bridge with a novel gusset-less curve-welded connection. A truck load test is used to validate the multi-scale model by comparing numerical results to the field collected data through the structural health monitoring system of the bridge. The result shows that the multi-scale model can determine the critical hotspot stresses, to study the fatigue performance of the bridge's critical components.