The Research Of The Methods In The Second System Stress Of Orthotropic Beck

With the development of science and technology, the technique of thin wall flat steel box girder and orthotropic beck become one of the important markings of a national bridge level .There are mainly three methods in the second system stress analysis of the orthotropic steel deck, P-E method, the equivalent girder beam method and the FEM .The Issue which is the most adaptive in three methods of the second system stress of the orthotropic steel deck has been studied and discussed.This thesis chooses the typical models of the general orthotropic deck system to solve with three method. The models have been divided into two groups with the different diaphgagm distance, 3m and 4.5m.There are two load patterns in the models: the worst mode to the deck plate and longitudinal ribs, the worst mode to the diaphgagm. In order to get the accurate result with FEM, the computation, comparition and sum-up must be done in many kinds of the boundary conditions. This thesis grasps the rule of the second system of the orthotropic deck and every component's effect. This paper compares the results of these modals with three methods.With the computation and comparition, it is found the rule that in the worst mode to the deck plate and longitudinal ribs when the diaphgagm distance is less than 3 m, the difference between the results with P-E method and equivalent girder beam method and the result of FEM is less than 10% which means the precision of three method is approximate; when the diaphgagm distance is more than 3 m, the difference is more with the distance increasing, the results of P-E method and equivalent girder beam method can not be adapted; in the worst mode to the diaphgagm, the results of P-E method and equivalent girder beam method can not be adapted.The P-E method and equivalent girder beam method are the simplified analysis ways, with some hypothesis. Their boundary condition are strict, and the results are not precise, especially in the worst mode to the diaphgagm. The finite element method can simulate the structure accdurately, it is the trend of the computation of the second system stress of the orthotropic deck. But it's result include the stress of the third system. In order to apply the finite element method and combine the fatigue estimation system the more conveniencely,the thesis put forward to construct a new system for the steel orthotropic deck .