| Because of the advantages of low weight, big ultimate bearing capacity, easy to assemble connection, structure good continuity and so on, the orthotropic steel bridge panel has been widely applied in the large span Bridges. Because the orthotropic steel bridge panel belongs to the thin-walled structure. In the service period of the bridge, the construction bear the high frequency load directly under wheel prone to fatigue cracks. The finite model of the orthotropic steel bridge deck has been established in this paper with fatigue cracks. The fatigue crack propagation rate was studied based on the theory of fracture mechanics, and the crack morphology, site, size effect on the fatigue life were evaluated. Here is the main content:1. Reviewed the development course of orthotropic steel bridge panel since the second world war, Summarized the research results about fatigue of Japan,European and US. Analysed the orthotropic steel bridge panel fatigue problems existing in China.2. The finite element model with details of typical structure has been established. Calculate the stress history of the different structural detail parts under different axle load. Evaluate the influence of different axle load to the structural detail parts on the orthotropic steel bridge panel on the basis of miner linear damage cumulative theory. Summarized the details which are sensitive to overload and welding defects.3. The finite element model has been establishedwith initial cracks.(The weakest part of cut out in web of crossbeam between two adjacent longitudinal ribs; Welded connection ends of transverse rib web to longitudinal rib; Fillet weld connection of longitudinal rib to deck plate), Calculate the stress intensity factor of the crack tips under different condition of wheel load, Classify the structure detail parts crack initiation form, Analysis of the fatigue crack propagation rate under different circumstances based on the theory of fracture mechanics. And make a shape optimization of the weakest part of cut out in web of crossbeam between two adjacent longitudinal ribs which are easy to occur. The fatigue damage occur cracks. |
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