Research On Structure Performance Of Steel And Concrete Composite Curved Girder Bridge

With the development of construction and transportation industry in China, steel and concrete composite curved girder bridge, due to its graceful curves, good adaptability to roads and its ability to span, has become an important bridge style in modern traffic engineering. Because of the lack of relevant codes, in the steel and concrete composite curved girder bridge design, normally there have been such difficulties as the shortage or the complete inexistence of design guidelines. Therefore, there is an urgent need for the research on and supplementation of such information. This article first introduced the curved girder bridge design and construction problems as well as a reasonable choice of finite element software to analyze the steel and concrete composite curved girder bridge in question; then it described the calculation theory of the bridges and practical method of calculation, focused on the introduction of finite element modeling method and related theory for a particular three-span continuous curved steel-concrete composite girder bridge; finally, it studied the factors affecting the characteristics of response of such bridge to loads, with some valuable conclusions obtained.The results of study indicate that:(1) for a three-span continuous curved girder bridge under only the vertical load, if its radius of curvature is greater than 200m, its internal forces can be replaced by a corresponding straight girder, with an error of less than 5%; with the only consideration of torque, the same conclusion can be obtained if its radius of curvature is greater than 300m; furthermore if its radius of curvature is greater than 200m, the effects of its curvature on its natural frequencies can be ignored;(2) under second phase of dead load, the relative slippage between the steel box girder and top concrete deck has a marked influence on the longitudinal stress in the deck, but a little impact on the longitudinal stresses at the bottom of steel girders, deflection, overall stiffness and transverse deformation of the bridge;(3)it is quite necessary to take reinforcement into consideration in the establishment of shrinkage and creep model for a continuous composite curved girder bridge; the effect of shrinkage and creep is prominent in the early stage of loading; the effect of shrinkage takes up 70% of the total of the two;(4) with the multiple temperature increase, the horizontal displacement of bridge deck, the maximum middle span deflection, the tensile stresses in the concrete deck over the piers, increase proportionately; with increasing temperature, there is an greater tendency for the girder to be disconnected with the bearing at the piers; tensile stress resulting from the lowering of temperature is greater than that from the rise of temperature of the bridge as a whole;(5) prestressing effect significantly increases the carrying capacity of sections with positive moment and cracking load at sections with negative moment, delaying the appearance of cracks.