Fatigue Behavior Research Of Orthotropic Steel Bridge Deck

Orthotropic steel bridge deck has many advantages as one of the main configuration of steel bridge deck, for its light weight, high bearing capacity, wide application, short construction period, low girder height, beautiful appearance and so on, it is favored by domestic and overseas bridge designers. In China, most bridges that have been completed and in construction adopt orthotropic decks. For the complex configuration ,serious effects of residual stresses, at the same time, the steel bridge decks are directly under wheel loads, some details are prone to fatigue, when the fatigue cracks propagate a specific length, the service safety of the whole bridge will be intimidated. With the increasing of orthotropic steel bridge deck in medium-long span bridges, larger traffic volume, over loading and oversize worsen the situation further, and it is imperative to study the fatigue behavior of orthotropic deck immediately.In this thesis, the following aspects are investigated:1. The general situation of steel deck applications and configuration characteristics are introduced. Domestic and overseas development situations and fatigue behaviors situations are summarized. At the same time, the paper sums up the fatigue evaluation and design methods for orthotropic steel bridge decks.2. Basing on summarizing the fruits of projects experiences and fatigue experiment researches, aiming fatigue cracks appeared at the key details of orthotropic steel bridge deck, such as cracks at the rib-to-deck, the rib-to-crossbeam, the rib connection and so on, the generating mechanism of the fatigue cracks are analyzed, the influence factors are discussed together, combined with European bridge design code, the corresponding fatigue details are classified.3. Applying shell-element to build 3D FEA model, different holes for rib passing crossbeam are analyzed. The investigation indicates that the improved Haibach hole and circle hole are better than ellipse hole, and should be used in rib-to-crossbeam connection precedently, but the application of circle hole need further verifications of fatigue experiments. By changing parameters, the paper studied the influence of plate thicknesses on fatigue behavior of the rib-to-crossbeam, and gave reasonable plate thicknesses for the connection. Based on FEM anlysis and investigations home and abroad, fatigue design advices and manufacture items for orthotropic steel bridge deck are proposed.4. For the fatigue cracks appeared in projects, combine with maintenance and reinforcement demands, such as saving retrofit time and costs, disturbing traffic as little as possible and so on, the paper give some methods for maintenance and reinforcement.