Distortion Effect Analysis Of A Slip In Steel-concrete Composite Box Girder

Steel-concrete box girder is a kind of bridge structure widely used nowadays.By connecting steel girder and concrete plate with shear connectors,the advantages of steel girder and concrete structure can be brought into full play.When the box girder structure is under stress,it will produce the longitudinal warping stress.Because the shear connector is not completely rigid,the slip phenomenon will occur when the steel girder and the concrete interface is under stress,it provides a theoretical basis for the study of the distortion effect of steel-concrete composite box girder considering slip in this paper.This paper studies the distortion effect of composite box girder through three parts:(1)The energy variational method based on the principle of potential energy is used to analyze the distortion effect of steel-concrete composite box girder without considering slip.The expressions of warpage strain energy and transverse frame strain energy of composite beams are given,and the fourth-order distortion control differential equation of single-box-single-cell trapezoidal box girder with unknown distortion angle is established,the expressions of distortion angle,distortion warpage,distortion double moment and distortion moment are obtained by using initial parameter method.(2)Based on the principle of potential energy stationary value,the distortion warping stress considering slip is established by introducing the slip angle displacement function,and the distortion differential equation considering slip is established.In this paper,an effective coefficient of distortion slip is proposed,which is only related to the properties of concrete and steel materials,the types of studs and the arrangement of studs,the initial parameter solution of the distorted differential equation is given.The Ansys finite element model of steel-concrete composite box girder considering slip is established.The distortion stress and distortion angle under uniform load are in good agreement with the derived formula.Whether the slip results are considered in the comparative analysis,the results show that the distortion angle and distortion warpage under uniform load are smaller than those without slippage,and the distortion angle under slippage is closer to the finite element results The results of distortion double moment and distortion moment are larger than those without considering slip.The distortion angle considering slip under concentrated load is smaller than that without considering slip,and the distortion warping,distortion double moment and distortion moment are similar.(3)Based on the deformation differential equation of steel-concrete composite box girders,the effects of slip stiffness,ratio of span to height,ratio of height to thickness and ratio of wing width on distortion angle and distortion double moment of composite box girder are analyzed respectively.The distortion angle increases with the increase of slip stiffness,span-height ratio and height-thickness ratio,and decreases with the increase of wing width ratio.As a whole,the influence of box girder height on the distortion effect of box girder is more obvious than other geometric parameters.