Study On Mechanical Properties Of Through Type Continuous Beam Arch Composite Steel Bridge

Recent years, with the rapid raise of the output of steel, more and more steel bridges have appeared in China. Through type continuous beam arch composite steel bridge has both advantages of steel bridge and continuous beam arch composite bridge, lowering the construction height under the premise of maintaining the rational distribution of force. Meanwhile, this type of bridge could be built with high speed, which has beautiful shape and broad prospect in engineering application.Based on Meilin Bridge located in Yixing Jiangsu Province, researches have been done on the mechanical properties of through type continuous beam arch composite steel bridge from four aspects, such as beam arch cooperation mechanism, analysis of structural parameters, shear lag effect of steel box girder and the ultimate capacity of structure.(1) Use structural mechanics method and derive the formula of load ratio for arch ribs. Analyze the influence of structural parameters on the ratio as mentioned above and find out that the girder of side span has little influence on this ratio while the girder of middle span and the rigidity of suspenders have greater influence on it.(2) By means of building up a truss element model, the influence of the arch beam rigid ratio, the angle and the arrangement form of cross arms between the arch ribs on the vibration frequency and mode have been analyzed.(3) Build up an ABAQUS shell element model for the whole bridge and analyzed the shear lag effect of steel box girder. This paper made a comparison between the shear lag effect of vehicle load and lane load, founded that the shear lag coefficient of lane load was less than that of vehicle load in the middle span, while they were almost similar in the side span. Under the case of partial loads, the shear lag coefficient caused by vehicle load is slightly larger than the case of symmetrical loads.(4) Based on the ABAQUS explicit dynamic analysis model of the background bridge, the ultimate capacity has been studied and values under each case are obtained. The calculation result turned out that the minimum structural safety coefficient of live load is 8.6 times of lane load and human load, which indicates that the structural operation safety reserve of the background bridge is sufficient.(5) Based on the completion experiment of the background bridge, the static and dynamic performance has been evaluated. Meanwhile, by means of comparing the values obtained from filed test and finite element model, the correctness of the truss element model and shell element model built in this paper is confirmed.