Study Of Structural Detail On Fatigue Properties Of Orthotropic Steel Bridge Deck

Orthotropic steel bridge deck has been widely utilized for the modern bridges around the world, due to its large spanning ability, light weight, strong bearing capacity, convenient construction and economy etc.. However, owing to the comprehensive factors including its complex structure, numerous welded joints, residual stress, initial defects and the complex loading etc., fatigue issue is arised in orthotropic steel bridge deck.Based on the hot spot stress method, the fatigue properties of welded structure details evaluted by the hot spot stress and stress concentration coefficient in orthotropic steel bridge deck were investigated in this paper. The main research contents is as follows:1) The development and application of orthotropic steel bridge deck were reviewed and the fatigue problem caused by the welding methods was analyzed. After that the general application of the hot spot stress method in welded structure was introduced.2) The basic theory of orthotropic steel bridge deck was described, including the definition of fatigue, the cumulative fatigue damage theory, and the calculation method of fatigue assessment.3) Two welded construction details of orthotropic steel bridge deck were analyzed. One detail is at the terminal connection weld between rib and diaphragm and the other is at the rib-deck weld. According to the analysis results of the force mechanism and the present research achievements at the above two weld types, the main effect parameters at each detail were achieved and made a preparation for the following calculation analysis.4) The concept and calculation method of the hot spot stress and stress concentration coefficient were introduced. In view of the above two welded construction details, the hot spot stress and stress concentration coefficient were regarded as the indexes based on the tests. And the effects of fatigue properties caused by the changes of each main parameter in the two details were analyzed. Some conclusions were achieved as a reference for improving the fatigue properties in orthotropic steel bridge deck and a prepartion was made for the following further research in this paper at the same time.5) Based on the theory of regression analysis, regression equations between the the hot spot stress and stress concentration coefficient indexes of the above two welded construction details and each main influence parameter such as structural thickness, height, welded penetration rate were obtained.The influence degree of the parameters in each index can be seen from the regression equation.