Study On Mechanical Behavior Of Corrugated Steel Web Composite Box Girder Bridge

Composite box girder bridges with corrugated steel webs arouse wide concern due to various advantages such as small weight,high prestressing efficiency,no inclined cracks on webs and better durability.Compared with the general concrete box girder bridges,Composite box girder bridges with corrugated steel webs have different mechanical properties and more problems requiring special consideration in design calculation.This dissertation researches systematically the shear lag effect,the web shear deformation and corresponding computational methods of composite box girder bridges with corrugated steel webs in the light of model test.The analytical theory on the shear lag effect of curved and multi-cell box girders with corrugated steel webs is established.The finite beam-segment element program is compiled considering the shear lag effect and web deformation effect for the purpose of application.The experimental scheme is designed for the test of shear lag effect and shear deformation effect of composite box girder with corrugated steel webs.The test models are made for the simply supported and two-span continuous single-cell box girders with corrugated steel webs.The relationship between load and displacement is tested under various loading conditions and the distribution of longitudinal stress is obtained.The test verifies the correctness of the theoretical analysis and confirms the obvious shear lag effect existing in the top slab of box girders with corrugated steel webs.It is shown that the double effect of shear lag and web deformation has significant influence on the vertical displacement of box girders.The mechanical characteristics of composite box girders with corrugated steel webs are summarized.The finite element program based on the spatial beam segment element is compiled by applying FORTRAN language for analyzing static and dynamic properties of box girders with corrugated steel webs.The web deformation effect and the characteristics of composite box girders are considered in the element stiffness matrix.The top and bottom slabs contribute to the bending stiffness of composite box girders.The shear lag effect is also involved in the program compiled.The results from the program are in a good agreement with those from the shell element in ANSYS.The double effect of shear lag and shear deformation in the composite box girders with double and three cells is analyzed by applying the energy variation principle.The formulas of deflection,stress and shear lag coefficient considering the double effect of shear lag and shear deformation are obtained.The shear lag effects under different loading conditions are compared.The theoretical analytical results from the present dissertation are compared with those by applying the shell element in ANSYS.The theoretical results considering the double effect of shear lag and shear deformation are in a good agreement with those by the ANSYS.The present research work can provide a reference for relevant design.According to the curved bar theory,supplementing shear lag warping displacement function of second-order parabola in the basic deformation of flange slabs of curved box girder with corrugated steel webs,the governing differential equation and boundary condition are established considering restraint torsion and coupled effect of bending,shear and torque by applying energy variation principle.The effect of secondary shear deformation on the warping displacement is considered in the restraint torsion analysis of curved box girder.The Galerkin's method is applied to solve the differential equations of the curved box girder with corrugated steel webs and an numerical example is provided.The refined finite element model of the curved box girder with corrugated steel webs is created and the numerical analysis is completed.The numerical results are compared with the analytic results of displacement and stress.It validates the correctness of the present analytic solution and the finite element analysis.