Research On Stress Calculation Theories Of Orthotropic Steel Bridge Deck System Of Steel Box Girder

Steel box girder has the advantages of light weight,fast construction and high strength.As an ideal form of long-span bridges,this kind of structure has been widely used in cable-stayed bridges and other types of bridges.As an important component of steel bridge system,orthotropic steel deck not only acts as a direct bearing of wheel load,but also acts as a part of the main beam.The mechanical behavior of the steel deck is very complicated.Generally,calculation and Analysis of orthotropic steel bridge deck is divided into three systems.This paper focuses on the stress calculation method for the second system of the bridge deck.Based on the theory of elastic mechanics,analytical methods suitable for stiffened panels with closed sections is introduced in detail,such as Pelikan-E?linger method,grillage method,finite element method.With a single span steel bridge deck to verify the equivalent beam grillage method and finite element method,found that the calculation results of the panel directly under the wheel load in finite element method is far greater than the other two methods.This is because the deformation panel is much bigger than the stiffening rib.Therefore,the finite element calculation can better reflect the real situation of the structure.Then,based on the Fourth Bridge project of the Fanhe River,the internal force of the bridge deck under four loading conditions was calculated by using the P-E method.And the detailed calculation process was given.Equivalent beam grillage model and finite element model are also established for results comparing.The errors between the results from three methods are analyzed.The calculation results show that that the location of stress peak appeared at the place where bearing the wheel load,and soon decay from the peak to the both sides,which means the transverse distribution of bridge deck under load is not uniform.With the help of finite element model,the influence of the diaphragm spacing,the stiffener height,the panel thickness and the stiffener thickness on the stress of the second system of the bridge deck is analyzed.The steel box girder structure is widely used in flexible high order statically indeterminate structures,such as cable-stayed bridges,and has strong geometric nonlinear effects under the action of loads,The orthotropic steel deck of cable-stayed bridge is subjected to large axial load during the service,and it is in the state of bending and pressure coupling,By means of a single span bridge deck model,the flexural stress growth law of orthotropic steel panels under different axial load levels is obtained,Then,based on the actual engineering background and the finite element analysis model,the nonlinear analysis of the steel deck of the Fourth Bridge project of the Fanhe River is carried out.It is found that the stress of the second system increases by about 10% when the axial force is taken into account,and the increase of the fulcrum position is higher than the mid span position,and the upper edge of the cross section is higher than the lower edge of the cross section.This effect should be paid attention to in the design and calculation of orthotropic steel bridge decks of cable-stayed bridges.