The Distortion Behavior Of Composite Box Girder With Corrugated Steel Webs

As a new type of composite structure bridge,the box girder bridge with corrugated steel web has attracted wide attention in the world for its superior performance.For the mechanical behavior of composite box girder with corrugated steel webs,there have been a lot of studies on bending and shear properties,but the research for the behavior of restrained torsion and distortion is short,and the theoretical and experimental studies are not sufficient.In this paper,the distortion behavior of composite box girder with corrugated steel webs is studied.The main work is as follows:1.By summarizing the existing distortion theory of corrugated steel web composite box girder,it can be found that the existing theory is deduced and established on the basis of the distortion theory of thin-walled box girder.The distortion theory of box girder with corrugated steel webs is divided into five types,among which the most widely used theories of the first type and the second type take the distortion angle as the basic displacement parameter,and the distortion control differential equation is established based on the static method and the energy method respectively.After comparing the two theories,it is found that the form of the distortion control equation is consistent,but the two theories cannot be unified into one because the distortion warping moment of inertia is different.2.Based on the distortion theory of thin-walled box girder and combined with the structural characteristics of composite box girder with corrugated steel webs,the calculation method of distortion generalized coordinates is improved and developed.Using the principle of minimum potential energy,the distortion control differential equation considering shear deformation has been extended.Compared with the two most widely used distortion theories,the new distortion theory fully considers the influence of shear deformation.Considering the relation between distortion angle and distortion warping function,the new distortion differential equation can be reduced to a form that does not consider shear deformation.Since the distortion warping moment of inertia of the three theories is not unified,the degenerated distortion theory and the first two theories cannot be unified into one theory.3.The distortion differential equation of the new theory can not be solved by the elastic bed beam analogy method.In this paper,the finite beam method is used to obtain the stiffness matrix of the distortion element and the load vector by taking the homogeneous solution of the distortion control differential equation as the displacement model.Based on the existing literature on the differential equation of rigid torsion of composite box girder with corrugated steel webs,the element stiffness matrix and load vector of rigid torsion can also be derived.The program was programmed with Fortran language,and the results of rigid torsion and distortion normal stress were obtained,which are in good agreement with the results of existing solid model experiments.4.The calculation program established in this paper analyzed a three-span corrugated steel web composite box-girder bridge,and the obtained stress results are in good agreement with the calculation results of the three-dimensional simulation model.Compared with 3d simulation model,this program is simple in modeling,and the calculation results basically meet the requirements of engineering design in the force analysis of the whole bridge.Based on the calculation program,the influence of rigid torsion and distortion effect caused by live load is analyzed.The obtained stress envelope diagram and stress amplification factor are of certain reference value to the analysis of practical engineering.