Static Behavior Analysis And Experimental Investigation Of Accelerated Construction Steel-Concrete Composite Small Box Girder Bridges

When the replacement, maintenance or newly-built bridges happens in the urban area, it always came with traffic jams. What’s more, the quality is out of control because the weather has great influence on the in-site construction. Aiming at existing problems on bridges replacement, maintenance or newly-built bridges for small and medium span in the construction of urban infrastructure facilities,this paper proposed a high performance steel-concrete composite small box girder bridges. Take advantage of oriented -prefabrication production, low beam depth and large rigidity,which can give full play to the strength of the steel and concrete material, it is suitable for the accelerated construction of medium and short span bridges. The related experimental and theoretical research was conducted after the discussion of the methods for structure design and construction. The main work and achievements are as follows.(1) The key technical problems of accelerated high performance steel-concrete composite small box girder bridges include standard module selection, arrangement of longitudinal and transverse diaphragms, the type and partition of bridge deck, the application of high performance concrete, the longitudinal and transverse joints, the design and layout of group studs, the deployment of posttensioning, the contents and methods for the calculation of whole bridge, the installation et. All of these issues are considered in this work.(2) Simulating the construction of accelerated high performance steel-concrete composite small box girder bridges, four accelerated high performance steel concrete composite beam were design and constructed. The mechanical properties and the reasonable arrangement of grouped shear studs were studied after the implement of experiment. The suggestions for the calculation of deflection, stress and ultimate loading capacity were given.(3) The fine finite element model of single beam was established. The load deflection curve, ultimate loading capacity, slip and stress were compared with the test results. The model establishing method and the theoretical calculation formula were studied. The plasticity design method can get the ultimate flexural bearing capacity of grouped stud composite beams exactly. Using the transformed section method,the calculated steel beam stress is greater than FEM and tested results.(4) After the summary of composite beam splitting mechanism, the fine finite element model of push-out was established. The performance of group studs and concrete under complex stress condition were analyzed. And the improve measures were proposed. With the using of bending force and posttensioning, the average shear capacity and shear stiffness improves a lot. When the height is larger than four times the diameter of stud, the height of stud has little effects on the average shear capacity and shear stiffness.(5) Adopting of the double shell element and spring element, a model of forty meter span accelerated high performance steel-concrete composite small box girder bridge was established. The response of structure along with the change of group studs stiffness was analyzed. The stress and deflection of bridge were checked. Under full composite action,the stress and deflection of group studs composite beams do not much affected by the group studs stiffness. With the decrease of the degree of shear capacity, the stress and deflection of composite beams increased slightly. The ultimate limit states and serviceability limit states of bridge were checked by. And it reserves high security.