In-plane Stability Performance Research And Design Method Of Cold-formed Circular Steel Tube Arch

Arch is an ancient structural system,and due to its beautiful shape,light structure and high carrying capacity,arch is now widely used in the field of building structure and bridge structure.Stability problem is an important control factor in arch structure design,Although the current theoretical research on the stability of the arch plane is relatively comprehensive,there are aslo lost of differences in the theories and formulas of in-plane stability design methods of steel arches proposed by scholars and specifications.And press bending is one of the cold-formed processes of curved steel tubes commonly used in engineering,the research on the influence of press bending formed residual stress on the in-plane stability theory of arch is still almost blank.Therefore,it is of great theoretical and practical significance to study the in-plane stability of circular steel tube arches after press bending.This paper uses the analytical methods and finite element methods,residual stress and strain distribution of press bending formed steel tube,studies the in-plane elastic buckling load of circular steel tube arch and the in-plane elastoplastic stability bearing capacity considering press bending formed residual stress and strain,and proposes a corresponding in-plane stability design method of the arches.Based on the plane cross sectional assumption and other theoretical assumptions,this paper establishs a steel tube micro-element segment model,and the theoretical solution of stress and strain of steel tube section in press bending formed process is derived by using equilibrium method.And the finite element software ABAQUS is used to simulate the press bending process of circular steel tube,combined with numerical analysis results and theoretical solutions,the paper proposes the residual stress-strain distribution pattern of the circular tube section after press bending.Writing the parametric modeling analysis scripts to achieve full automation of model preprocessing modeling and post-processing analysis processes,thereby improving the efficiency and accuracy of modeling analysis.Combined the fiber technique and initial defection addition technique,the in-plane stability analysis model of the circular steel tube arch is established in batches under the premise of verifying the accurate and reasonable parameter setting of the finite element model.This paper studies the in-plane elastic buckling problem of cirualr steel tube archin unifoem compression,and the parametric modeling analysis method is used to analyze the influencing factors and variation law of the buckling critical load.Considering the classical theoretical solution of the arch,the deformations before the buckling and the compressible condition of the arch axis,the calculation method of the in-plane buckling critical load of the circular steel tube arch based on the elastic buckling coefficient is proposed.Considering the effects of material nonlinearity,geometric nonlinearity and initial defections,this paper establishs the in-plane elastoplastic stability analysis model of the arches subjected to uniform compression or axial force and moment in batches.Combined with the results of numerical analysis and existing research results,the influence of different geometric parameters,residual stress and strain on the in-plane stability bearing capacity is discussed.Under different arch conditions and based on the regularized slenderness ratio,this paper proposes the calculation formula of the in-plane stability coefficient of steel tube arch in uniform compression,and also puts forward the design method of the in-plane elastoplastic stability bearing capacity of the cirular steel tube arch subjected to axial force and moment.Finally,the numerical analysis results of the test model verify the applicability,rationality and reliability of the design formula,which can provide a certain reference for the practical application.