Research On Fatigue Behaviour Of The Steel-Concrete Composite Bridge Deck Of Long-span Suspension Bridge

With the rapid development of the economy,the traffic load of the bridge during the operation period also increases,which is a severe test for many bridges.There are many problems in the engineering application of the traditional bridge deck system,which provides a new opportunity for the development of the new steel-concrete composite deck system.The new steel-concrete composite deck system has been widely used in long-span bridges because of its advantages such as material performance,light weight,easy transportation,easy installation,good stress and so on.However,the research on this new structure is not a lot so far,the theoretical system is not perfect,especially in the study of fatigue performance on the large span suspension bridge steel-concrete composite bridge system is very rare,and the fatigue damage is an important factor in the disease of the bridge deck system.Therefore,it is especially important to study the fatigue performance of the new steel-concrete composite deck system.Based on the combination of theoretical analysis,numerical simulation and experimental research,the fatigue performance of steel-concrete composite deck system is studied in this paper.The main work as follows:First of all,by reading a large number of domestic and foreign literature,the research and application of steel-concrete composite bridge deck system are described in detail,the field of research deficiencies were found,and the new steel-concrete composite bridge deck fatigue research was put forward.Secondly,the fatigue theory and calculation method of the new steel-concrete composite deck system are introduced in detail,including the design principle and design method of the fatigue resistance of the new steel-concrete composite deck system.Thirdly,the fatigue load model of highway regulation in Britain,USA,Europe,Japan and China is described,ANSYS finite element software is used to simulate a large span steel-concrete composite bridge deck suspension bridge.and the fatigue load model is used to analyze the calculate model.Then,the scale model of the bridge deck is made according to the proportion of 1:4,and the test is carried out under static load and fatigue load.Finally,the differences between the calculated results and the experimental data are analyzed.The results show that the load size of the vehicle is proportional to the amount of fatigue damage,and the influence of the load size on the fatigue damage of the steel-concrete composite deck is very significant.In order to prevent the fatigue damage of the highway bridge,the overloading of the bridge should be eliminated.During the fatigue test,the welding surface of the I-beam and the web is the first to be damaged,and the damage is most serious.The main reason is that it is located in the welding site where the fatigue is broken,and its stress amplitude is the largest.During this test,the damage was not found in the I-beam and concrete connections,and the shear key was working well.