Local Stress Analysis Of Orthotropic Bridge Deck For Railway Steel Truss Bridge

With the progress of the times,orthotropic steel deck has been widely used in various bridge projects because of its light weight,low structure,high bearing capacity,good overall performance and relatively short construction period.However,due to the stress concentration caused by welding,the cracks in the structural details are easy to generate cracks,and then develop into dangerous behaviors such as fracture.Therefore,this paper will study the stress distribution of the bridge deck system,find out where the stress concentration is likely to happen,and make corresponding measures to reduce the stress concentration.The project background is a two line down bearing steel truss girder of the ballast bridge deck in central and southern Shanxi,with a full length of 81.5m,and its calculation span is 80 m of the bottom bearing steel truss bridge.In this paper,the finite element analysis of the bridge deck system is used to carry out the finite-element analysis.The full scale model A and the model B are established respectively.The stress performance of the lower deck steel truss bridge deck system is systematically studied.The main work and results are as follows:(1)The length of three beams in the actual model is selected vertically by the model A,and the middle crossbeam is taken as the research object,and the ends of the crossbeams are used as boundaries.The influence of different confining modes and diaphragm opening on the force is analyzed.The analysis results show that only the two ends of the bridge deck are treated simply,and the U stiffener is not constrained,and the stress reaches the most unfavorable state.In addition,through the comparison of the opening form under various specifications,the opening form of the railway is better in Europe.(2)Model B takes the structure of two main truss nodes in the standard section of the bridge deck as the research object,uses the space plate and shell element to establish the local finite element model,carries out the stress analysis under different load conditions,and obtains the most unfavorable load loading position,and then changes the roof thickness,the distance between the transverse beams,the height of the U ribs and the thickness,and then makes a comparison on the effect of its stress.Comparison and summary.The results show that with the increase of the thickness of the roof,the thickness of the U ribs and the increase of the height,the stress concentration can be improved effectively,but the increase of the spacing of the beams has an effect on improving the stress concentration.(3)In view of the above research results,the existing bridge is analyzed and optimized locally,opening the hole in the stress concentration area and optimizing the arc gap,so that the stress state of the orthotropic steel bridge panel is effectively improved and the stress concentration is reduced.(4)The causes of cracks are analyzed and summarized.Then a scheme of controlling cracks is put forward based on the stress characteristics of engineering cases.The research results in this paper can be a reference for the design of simply supported steel truss girder.