Research On The Influences Of Pavement On The Fatigue Performance Of Orthotropic Steel Bridge Deck

Orthotropic steel deck has to face severe fatigue problems due to its numerous crisscrossed slabs and three-dimensional weld joints which result in complex mechanical state and significant stress concentration. On the other hand, fatigue designs of orthotropic steel deck are mostly considered from its own structural parameters. However, the research combined with deck pavement is relatively few. Considering the action of pavement, in this thesis, it was firstly discussed that the influences of pavement parameters on the fatigue properties of typical details in orthotropic steel deck by FEM (finite element method). Secondly, the safety of the pavement simplified methods which widely used at home and abroad were verified. Finally, the diffusion angle of wheel loading area was discussed for fatigue problems. The details of the research are as followings.(1) The development course of orthotropic steel deck was reviewed, the types and locations of steel deck fatigue cracks were summarized, and the available references and research about pavement and steel deck which worked together were studied;(2) The mechanism of steel bridge fatigue and the types of structure fatigue damage was explained, the conversion process of fatigue strength between variable range and constant range was described, and the dispose methods of the stress history was presented;(3) Characteristics, material composition and structure forms and main diseases of deck pavement were summarized, the varied range of pavement parameters was determined. And the simplified methods which were commonly used were studied to provide theoretical support for FEM analysis;(4) The orthotropic steel deck finite element model including pavement was established, and the influences of layer unite state between deck pavement and the roof of steel deck, thickness, elastic modulus and structure forms of pavement on the fatigue properties of selected typical details in orthotropic steel deck were studied;(5) One of the pavement simplified method-the diffusing effect namely considering a diffusion angle instead of the action of pavement was analyzed, and the finite element model to carry out a proper diffusion angle for fatigue problems was established.