Out-of-plane Stability And Design Method Of I-section Circular Arch With Web Openings

As a new type of structure,web arch with openings has beautiful appearance,high bearing efficiency and easy access to pipelines above buildings.It combines the characteristics of arch and openings,and has been more and more popular with engineers in recent years.Because of the existence of the initial curvature,the geometric equations of bending,torsion and warping of Web arch are mostly coupled with each other,and the influence of the hole effect leads to the complex theoretical analysis.At present,there are lacks of systematic and perfect research on this kind of arch with complex characteristics,which limits its application in engineerings.The main work of this paper are as follows:(1)Considering the coupling effect of in-plane deformation and out-plane deformation of steel arch under radial uniform pressure,and considering the second order terms of in-plane and out-plane deformation coupling,the out-plane elastic buckling load formula of double-axisymmetric cross-section arch under radial uniform pressure is derived.(2)Through hole equivalent method,the out-of-plane buckling loads of web-opening arch and solid-web arch are correlated,and a modified slenderness ratio formula is proposed,which can take into account the flexural and shear capacity of the open-web arch and facilitate the calculation of out-of-plane elastic buckling loads of web-opening arch.(3)By means of finite element numerical method,the effects of initial geometric imperfections,rise-span ratio,slenderness ratio,arch foot conditions and hole parameters on the out-of-plane stability of open arch are analyzed.(4)For uniform compression and uniform bending,based on regularized slenderness ratio,the correlation coefficient formula is established by modified slenderness ratio.Based on the correlation coefficient,the expressions of out-of-plane stability coefficient of open-ended arch under different boundary conditions and different load conditions are obtained.For unequal end bending moment,the equivalent correlation coefficient method and the equivalent modified moment coefficient method are used to propose opening.The expression of out-of-plane stability bearing capacity of arch is studied,and the bearing capacity of open-ended arch under compression-bending load is studied,and the expression of stability bearing capacity of open-ended arch under compression-bending load is put forward.(5)The influence of rise-span ratio,slenderness ratio and arch foot condition on the threshold stiffness of elastic support of open-pit arch is studied.A new correlation function is established by introducing the modified slenderness ratio,and the expression of the threshold stiffness of lateral support based on the correlation function under different numbers of supports is proposed.