Research On Fatigue Performance Of The Steel-concrete Composite Bridge Deck Under Vehicle Loadings

Steel-concrete composite bridge deck which is a new type of structure has been used in large span suspension bridge and has achieved good economic benefits. The economy has got good result after using the new deck. With the increase in working time, traffic and vehicle loadings, the life of the bridge under service time has been reduced drastically. The fatigue problem of steel-concrete composite bridge deck under vehicle loadings is increasingly outstanding. At present, the research of steel-concrete composite bridge deck is focused on the static aspects, and there is less research of fatigue aspects in China. So it is significant that we research the fatigue performance of steel-concrete composite bridge deck under vehicle loadings. In this paper, we combine the actual traffic survey data of the highway-bridge and finite element analysis method to research the fatigue performance of steel-concrete composite bridge deck under vehicle loadings. Detailed research contents are as follows:(1) After reading Chinese and foreign related literature, this paper has carried on the detailed introduction which is about the basic theory and calculation method of steel-concrete composite structural fatigue. By comparing the merits of various methods and the actual situation, we choose the S-N curve of Miner standards to analyze the fatigue damage and life.(2)Through the calculation and analysis of the 24 hours’ traffic data of a highway bridge in Jiangsu province, trucks were grouped into 16 categories of common models. By using fatigue damage equivalence principle and the British BS5400 relevant norms, the 16 categories are divided into seven categories of models typical car. Then, we can establish a model vehicle load spectrum frequency value.(3)The steel-concrete composite bridge deck segmental model is established by the background of actual project, based on the theory of finite element method to study the fatigue properties. The seven categories of typical vehicles are loaded into the finite element model. The stress-time history data of steel-concrete composite bridge deck was obtained by using the transient dynamic analysis function of ANSYS. Then, People can calculate the fatigue damage and predict fatigue life of structure. It is found that the fatigue life of concerns(1)(point of forcing most negative) is lower than the design life(100 years). It shows that vehicle dynamic load significantly affect the fatigue properties of steel-concrete composite bridge deck. The vehicles of passing the bridge may overload, because the load spectrum of model vehicle were built from the actual traffic investigation.(4) Each concerns in steel-concrete composite bridge deck model, which is in the action of BS5400 and AASHTO standards fatigue car, is solved and analyzed the fatigue damage.Studies show that the fatigue damage of the point of forcing most negative in the steel-concrete composite bridge deck model is much larger than other locations. The differences of vehicle parameter value, such as total weight, axial spacing and single axle loadings, may cause the different amount of fatigue damage, leading to fatigue life of steel-concrete composite bridge deck differences.