Finite Element Analysis Of Mechanical Behavior Of Double Amplitude Curved Continuous Steel-concrete Composite Box Girder

Steel-concrete composite box girder bridge can effectively reduce beam height,reduce structural weight and facilitate construction.It is widely used in the construction of urban viaduct.Compared with straight-line box girder,the mechanical characteristics of Curved Steel-Concrete Composite Box Girder are more complex.While it is subjected to bending and shear,it is also affected by bending torsion coupling effect and spatial effect.In this dissertation,theoretical analysis,experimental research and numerical simulation are used to study the mechanical behavior of Curved Steel-Concrete Composite Box Girder.Firstly,by deriving the basic equation of curved beam,the main influencing factors of bending torsion coupling effect of curved composite beam are summarized;Then,taking the double amplitude curved continuous rigid concrete composite box girder bridge of Hangzhou ring viaduct as the engineering background,two test beams with radius of curvature of 26 m and 52 m are designed for static load test to preliminarily analyze and study the mechanical performance of Curved Steel-Concrete Composite Box Girder;Next,create an accurate finite element model by the finite element analysis software ABAQUS,verify the model reliability through the test data,and use Python language to develop ABAQUS to improve the modeling efficiency of the finite element model;Finally,use finite element numerical simulation method to research the effects of curvature radius,load form,concrete strength grade and the number of diaphragm on the mechanical performance of double amplitude curved continuous steel-concrete composite box girder.The main research results of this dissertation are as follows:(1)the greater the radius of curvature,the greater the ultimate bearing capacity of Curved Steel-Concrete Composite beam,and the smaller the mid span deflection and torsional angle of the structure.For the curved continuous steel-concrete composite box girder with the span of 2×4.5m studied in this dissertation,When the radius of curvature is between 20 m and 100 m,the curvature radius has an obvious influence on the bending torsion coupling effect and ultimate bearing capacity of the structure;When the radius of curvature is greater than 100 m,the radius of curvature hardly affects the mechanical characteristics of the structure.(2)Under the three working conditions of lane load studied in this dissertation,when the curvature radius of curved continuous steel-concrete composite box girder is in the range of 20 m to 100 m,the beam is twisted to the outside under lateral eccentric load and full bridge load,and the difference of support reaction force and torsion angle decrease with the increase of curvature radius;When the beam is loaded on the inner side,it turns to the inner side,and the difference of support reaction force and torsion angle increase with the increase of curvature radius.The lateral eccentric load has the greatest influence on the torsional effect of Curved Steel-Concrete Composite beams.(3)When the concrete strength grade of concrete slab is C40 to C60,it has little impacts on the deflection and ultimate bearing capacity of Curved Steel-Concrete Composite beam.The higher the strength grade of concrete,the less the increase of ultimate bearing capacity.Considering the engineering economy,it is suggested that the concrete slab with lower strength grade should be poured under the condition of meeting the design requirements.(4)The number of diaphragms has little impacts on the stiffness of Curved Steel-Concrete Composite beams.The setting of diaphragms between supports can increase the torsional performance of curved beams.It is suggested that the diaphragms should be arranged at the mid span and support in the steel box girder.