Stress Analysis On The Minjiang River Bridge Ballast Deck Through Girder Structure

The design of the bridge floor of the long span high way steel truss bridge is very important. The Minjiang River Bridge of the new railway line from Fuzhou to Xiamen is a (99+198+99) m continuous steel truss Bridge with flexible arch. The ballast deck of Minjiang River Bridge is achieved by the use of the trough girder supporting on the steel cross beam. And the section of trough girder is designed as "?"type.There are 18 trough girders on the bridge. And the trough girder has the advantages of small building height, a low noise effects, good space utilization of cross-section, and graceful appearance, low cost in total, and so on. Based on the Minjiang River bridge as a backdrop, the analysis of the Minjiang River Bridge deck trough girder is made in this paper. The main parts are as follows:①. Using the special software MIDAS, an entity model of the single trough girder is established, and made numerical analysis for it by entity element method. It Detailed studies a singer trough girder's spatial distribution of longitudinal normal stress, shear lag effect, transverse normal stress, vertical normal stress, and the horizontal shear stress under the action of dead load, prestressing force ,superimposed dead load and live load while supporting on the ground.②.It establishes a space gridiron model of trough girder, and adds it to the model of the whole bridge in this paper. And the analyses under the action the entire bridge self-weight, prestressing force superimposed dead load and live load are made respectively.③.The results of the whole bridge shows that the trough girder in the bridge are overstressed.So the stress of trough girder must be optimized . In this paper we apply the method of impact matrix ,and change the reactions of the trough girder by alter the height of the bearing in order to optimize the stress state of the trough girder.