Research On Shear Resistance Of Corrugated Steel Webs And Encased Concrete Of Long Span Box Girder With Corrugated Steel Webs

Prestressed concrete composite box girder bridge with corrugated steel webs has many advantages,such as lightweight structure,beautiful appearance,reasonable force,good seismic performance,economic cost and environmental protection.It has become a new type of bridge structure which has been popularized and applied in China in recent years.But compared with the traditional concrete continuous beam(rigid frame)bridge,the span of continuous beam(rigid frame)bridge of corrugated steel web is still at a small level.The main reason is that the relevant codes only think that the corrugated steel webs bear all the shear force of the box girder conservatively.The theoretical and experimental research is mainly based on the shear strength of the corrugated steel webs with small span and equal section.The shear mechanism and design method of the corrugated steel webs and the lined concrete of the long-span corrugated steel webs box girder bridge need to be improved.These problems have seriously restricted the development of box girder bridge with corrugated steel webs to larger span.Therefore,there are still some problems that have not been solved well or need to be further studied,although this kind of bridge type is popularized in our country at present.The research on shear design method of corrugated steel webs and encased concrete for large span corrugated steel web girder bridge is of great significance and engineering application value.In this paper,the scale model tests of shear behavior of corrugated steel webs and encased concrete steel-concrete composite webs of long-span box girder bridges with corrugated steel webs were carried out.The deformation and failure process of corrugated steel webs and encased concrete and the design parameters of different encased concrete,such as concrete thickness,stud density and reinforcement ratio,were summarized from the macroscopic level.The shear behavior of corrugated steel webs and concrete-lined steel-concrete composite webs of long-span box girder bridges with corrugated steel webs with variable cross-section was studied.The shear mechanism and load-bearing capacity calculation method in the elastoplastic stage of liner coagulation were proposed.The variable cross-section waveform was analyzed.The buckling sensitivity of structural parameters of steel webs and encased concrete was studied.The shear calculation method and checking calculation flow of encased concrete steel-concrete composite box girder were established.The main research contents include:(1)Scale model tests on shear behavior of large-scale corrugated steel plate and lined concrete webs were carried out.The shear strength and deformation characteristics of corrugated steel webs and encased concrete steel-concrete composite webs under 8 different design parameters were compared and analyzed.The deformation and failure process and regularity of corrugated steel webs with variable cross-section and concrete lining were obtained from macroscopic view.It provided an important basis for further theoretical analysis.(2)The formulas for calculating the elastic local shear buckling strength and the global shear buckling strength of corrugated steel webs were derived by Galerkin's method and Rayleigh-Ritz's method respectively.The influence of the structural parameters of corrugated steel webs on the buckling strength was discussed.The shear failure mechanism of encased concrete arch-truss mode and calculation method of shear bearing capacity,which considering the effect of reinforcement,were proposed.The calculation method of shear ratio in elastic-plastic stage of corrugated steel web-encased concrete composite web was established.(3)Based on the finite element method and ABAQUS large-scale finite element program,the finite element numerical model of steel-concrete composite web considering the contact relationship between bolts and steel-concrete was established.The validity of the numerical model was verified by comparing the results of laboratory test and numerical simulation.Based on a large number of Engineering examples,the commonly used structural parameters such as corrugated type,variable cross-section height and concrete thickness were summarized.The influence of different structural parameters on the buckling sensitivity of large corrugated steel webs was analyzed by numerical model.The optimum design range of structural parameters of corrugated steel webs and encased concrete was proposed.(4)The general formula of shear stress calculation for steel-concrete composite box girder room with corrugated steel webs was deduced by analytical method,and the formula for calculating the shear stress of the top and bottom plate and the corrugated steel web-encased concrete web,considering the thickness variation rate dt/dx = tan?of the bottom slab and the change rate dh/dx-tan ?' of beam height,was discussed.In view of the lack of shear resistance of encased concrete and roof and floor slab in current code,the process of checking the shear resistance of large span steel-concrete composite box girders with encased concrete was presented.(5)On the basis of the above theoretical research,taking Qianshan River Bridge of Zhuhai Connection Line Project of Hong Kong-Zhuhai-Macao Bridge as the background,the shear bearing capacity of long-span corrugated steel webs steel-concrete composite box girder was calculated by using the theoretical formula of shear design,and the shear stress and allowable range of corrugated steel webs steel-concrete composite box chamber of the background bridge were compared,analysis.The research results can provide important reference for the design of shear strength of large span box girder bridge with corrugated steel webs.