Analysis And Evaluation Of Fatigue Resistance Of Orthotropic Steel Bridge Deck

The orthotropic steel bridge deck, which is constituted by orthogonal stiffening ribs (longitudinal ribs and transverse ribs) and bridge deck slabs, to bear wheel load together. It has already become a kind of bridge structure form of the long span steel bridges in the world. However, Fatigue crack of the orthotropic steel bridge deck often happened at home and abroad in recent years. Due to the complexity of the orthotropic steel bridge deck structures, it’s difficulty to simulate the actual stress state of orthotropic steel bridge decks in the traditional way. Combining with the background bridge structure, this paper makes the following aspects:(1) By constraint equations, mixed finite element model including beam, plate and shell element is established to achieve different analytical precision. The calculation results are compared with the full-bridge refined finite element model. The results shows that mixed finite element method can accurately consider the boundary conditions of the structural force and displacement, and reflect the stress distribution on the large span steel box girder.(2) Taking the background bridge as the research object, discuss the impact on the orthotropic steel bridge deck of design parameters, such as height of U rib and thickness of bridge deck. Then these parameters are recommended for the new design bridge. On the basis of a summary of engineering and fatigue test results at home and abroad, a series of structure design recommendations are given for the key details for orthotropic deck, such as the connection between longitudinal ribs with roof, the connection between longitudinal ribs with beams and roof. For existing bridges, pavement material on the surface of the steel bridge can be altered. Lightweight composite deck can take advantage of the rigid pavement structure UHPC layer to reduce fatigue stress amplitude of steel deck. Mixed finite element method analysis shows that for mechanical properties before and after using deck structure of the background bridge, UHPC layer of lightweight composite bridge panel will make a greater contribution on the stress amplitude. It’s an effective way to reduce the stress concentration of steel bridge deck and fatigue cracking. (3) The most disadvantaged sites and various structural details of the stress state of four fatigue sensitive areas of orthotropic bridge deck are ensured by mixed finite element model. For the most disadvantaged sites, A preliminary study of the orthotropic rigid bridge deck fatigue performance test and monitoring scheme have been done.