Research On Mechanical Behavior Of Steel-concrete Continuous Composite Beam Bridge Under Operation

After the reform and opening up,with the continuous development of China’s economy and the improvement of urban infrastructure construction,steel-concrete composite girder bridges have become more and more widely used as emerging bridge structures.The steel-concrete composite structure is a new structure in which the steel beam and the concrete slab are integrally connected by a shear connecting member to realize a joint action.The steel-concrete composite structure can give full play to the advantages of good concrete compressive performance and good tensile properties of the steel structure,avoiding its shortcomings.In this paper,a steel-concrete composite girder bridge is used as the engineering background,and the bridge is numerically analyzed.The main research contents of this paper are as follows:(1)Explain the basic concepts and classification of composite beams,introduce the advantages and disadvantages of steel-concrete composite structures and the research situation at home and abroad,and put forward the main contents and research significance of the research.(2)The design theory of steel-concrete composite beams is studied.The force characteristics of composite beams are briefly summarized.The elastic analysis method and plastic analysis method of steel-concrete composite girder bridges are introduced.The creep effect of steel-concrete continuous composite girder bridges is introduced.And the calculation method under the temperature effect is elaborated in detail.(3)Using the joint section method in the finite element analysis software midas/civil to model and analyze the interchange of a city in Anhui,calculate the upper structure of the bridge.The effects of creep effect and temperature effect on the steel-concrete composite girder bridge are analyzed,Creep has a certain unloading effect on the deck,and this unloading effect will increase significantly between three years from the bridge to the bridge.After three years into the bridge,it will gradually slow down over time,eventually tending to stable.and the effects of creep parameters such as loading age and relative humidity on the creep effect are studied.The effects of creeping parameters such as loading age and relative humidity on the creep effect were studied.Further analysis and calculation of the influence of automobile load,relative humidity,steel girder and concrete deck height ratio on the crack width of negative bending moment zone of steel-concrete composite girder bridge.(4)Based on the stress characteristics of the negative bending moment zone of steel-concrete continuous composite girder bridge,the crack width of the negative bending moment zone of the steel-concrete composite girder bridge is calculated according to European norms,British norms,American norms and Chinese norms.By comparing the crack width of the concrete bridge deck in the negative moment zone when comparing different load combinations,it is concluded that the dead load and the vehicle live load are the main load factors affecting the crack width of the bridge deck in the negative moment zone.Furthermore,the influence of the height ratio of automobile load,relative humidity,steel main beam and concrete bridge deck on the crack width of negative bending moment zone of steel-concrete composite beam is further analyzed.