Study On Shear Lag Effect Of Steel-concrete Composite Oblique Box Girder With Inclined Web

With the advocacy of sustainable development and green development in my country,it is very necessary to develop new combined bridges.The steel-concrete combination structure can give full play to the excellent performance of concrete and steel,which is fully in line with my country's advocacy for green development.In addition,compared with the ordinary concrete structure,the combined structure has the advantages of light weight and short construction period.It has been widely used and developed in bridge engineering.However,the shear connection between the concrete roof and the steel web of the composite structure cannot be completely rigid.There is slip deformation between the two,which makes the stress on the concrete roof and the steel floor change greatly,and the shear lag effect is also obvious.Therefore,considering the sliding effect of the box girder with inclined web has theoretical significance and application value for the study of the shear lag effect.In this paper,through the theoretical derivation and numerical simulation of the steel-concrete composite oblique web box girder,the stress,deflection and other related issues are studied more comprehensively.The main research contents and conclusions are as follows:(1)The cubic function is selected as the shear lag warping displacement function.Based on the energy variation method,the control differential equation of the steel-concrete composite oblique web box girder without considering the sliding effect and considering the sliding effect is derived,and Analytical solutions for the stress and deflection of composite simply supported beams under uniform load,concentrated load and combined cantilever beam under uniform load and concentrated load at the end of the beam are solved.(2)Through the ANSYS finite element software,a simple composite supported box girder was established under uniform load,and the spring element was used to simulate the shear connection.The sliding effect between the steel web and the concrete roof was considered and the two were not considered.The two models of the slip effect are obtained,and the numerical solutions of the longitudinal stress of the top and bottom plates of the mid-span of the combined simply supported box beam and the vertical deflection value along the span of the beam are solved,and compared with the analytical solution.The analysis shows that the relative error of stress and deflection at the mid-span of the analytical solution and the finite element solution is the largest when considering the slip effect.The relative error of the top plate stress is 3.92%,the relative error of the bottom plate stress is 1.43%,and the deflection value The maximum relative error is 9.36%.(3)Change the shear stiffness of the connector through the finite element model,and study the influence of the shear stiffness on the deflection and stress of the composite beam.Research and analysis show that as the shear stiffness decreases,the stress of the concrete roof becomes smaller,while the stress and deflection of the steel floor become larger.Provide a reference for the design of composite beams in the future.