Study On Mechanical Performance Of Continuous Curve Double Box Steel-concrete Composite Bridge In Construction Stage

In the selection of urban viaduct and Expressway Overpass,the Continuous Curved Steel-Concrete Composite Bridge which can effectively reduce the beam height is often the best choice.However,curved beams have curvature,which makes the stress situation more complex.And the transverse connection of composite girder bridges in foreign countries is mostly truss type,so the research results in foreign countries are not fully applicable.In the construction project,the concrete wet load is completely borne by the steel beam,if the displacement between the boxes varies,there is the possibility of torsion.In this paper,based on the key technology research on construction of Continuous Curved Steel-Concrete Composite Beams(2018042),a science and technology project fund of Zhejiang Provincial Department of transportation,the experimental research on continuous curved double box steel-concrete composite beams is carried out and the relevant parameters are analyzed by finite element method.The main work and conclusions are as follows:(1)Taking the two span continuous curve composite beam around Hangzhou as the engineering background,three composite beam specimens are designed with the curvature radius and transverse connection system as parameters.The concrete slab is poured with positive and negative moment interval.The effects of curvature radius and transverse connection on the mechanical properties of composite beams are investigated.Research shows:a)The larger the radius of the curve,the smaller the tangential and radial strain,the smaller the vertical displacement and the smaller the gradient of change.b)The torsional angle of the mid span section of the composite beam with bolt connecting plate as the transverse connection system is larger than that of the curved beam with ordinary diaphragm.c)The tangential strain on the web is larger than that on the curved beam with ordinary diaphragm,and the tangential strain,radial strain on the bottom and vertical displacement plate are smaller.(2)The finite element model is established by using the finite element software ABAQUS,and the number of diaphragms is taken as the parameter for extended calculation.The results show that the more diaphragms are set up for composite beams,the smaller tangential strain is produced.The number of diaphragms has little effect on the change gradient of tangential strain in the middle of web.The smaller the vertical displacement and radial displacement in the middle of steel beam bottomplate are,the smaller the torsional angle of steel beam midspan section is.(3)The finite element model is established by using the finite element software ABAQUS,and the transverse section slope is taken as the parameter for extended calculation.The results show that the larger the slope of the two boxes of the composite beam is,the smaller the tangential strain is.The larger the slope of the two boxes of the composite beam is,the larger the vertical displacement in the middle of the steel beam bottom plate is,the larger the radial displacement in the middle of the steel beam bottom plate is,and the smaller the torsional angle in the middle section of the steel beam span is.(4)The finite element model is established by using the finite element software ABAQUS,and the thickness of diaphragm is taken as the parameter for extended calculation.The results show that the greater the thickness of diaphragm,the smaller the tangential strain on the web,the smaller the vertical displacement on the bottom plate of the box girder,and the smaller the torsional angle of the midspan section.(5)The finite element model is established by using the finite element software ABAQUS,and the pouring sequence is taken as the parameter to do the extended calculation.The results show that the tangential strain produced when the composite beam is poured in sections is larger than when the whole beam is poured.The strain of outer box girder is larger than that of inner box girder.The vertical displacement of inner box girder is larger than that of outer box girder.The largest torsional angle is produced during sequential pouring.(6)Midas / civil is used to build the whole bridge model to check the whole construction process.The results show that the stress value generated in each stage is less than the maximum allowable stress value,which meets the requirements of the code.