The Fatigue Life Analysis Of The Welded Detail Of Orthotropic Steel Bridge Deck And Longitudinal Rib Based On Lefm

In recent years, fatigue problems of welded steel bridges have become more and more prominent because of the increasing traffic loads. Their fatigue problems have become a research hotspot nationally and abroad. However, as one of the main types in long-span and mid-span bridges, the orthotropic steel bridge deck has not been explored extensively for its fatigue issue. Based on previous research on the fatigue life, fracture-mechanics theory can be applied to study the fatigue life of the detail of orthotropic steel bridge deck and longitudinal rib.In this thesis, the weld detail of orthotropic steel bridge deck and longitudinal rib is the focus of the analysis. The stress intensity factor, its effect parameters and fatigue life of cracks in the joint of orthotropic steel bridge deck and longitudinal rib were analyzed. The main research contents and approaches are listed as follows:1. The2-dimensinal finite element model of the joint of orthotropic steel bridge deck and longitudinal rib is created. The stress intensity factor was calculated.According to national specification, the initial crack was preset in the finite element model of the joint of orthotropic steel bridge deck and longitudinal rib. The stress intensity factor was calculated. With regard to structural parameters of the model, sensitivity of the stress intensity factor is analyzed. The results showed that the fatigue life can be improved by controlling the initial crack length or increasing the thickness of deck.2. The fatigue life of the joint of orthotropic steel bridge deck and longitudinal rib was forecasted based on fracture-mechanics theory.According to the European steel bridge specification and based on the Pari’s model and the previous stress intensity factor, the fatigue life of the joint of orthotropic steel bridge deck and longitudinal rib was calculated. The S-N curve of this thesis was fitted well with the S-N curve of the European steel bridge specification. The results in this thesis have the reference value.