Study On The In-plane Stability Of The Plate-tube Connection Steel Arch

In this paper,based on two different forms of a new type steel arch,namely the planar plate-tube-connected circular steel arch and the plate-tube-connected circular steel arch with inverted triangle section,the in-plane elastic stability and the elastic-plastic bearing capacity of the arch are studied,Based on the analysis of the influence of shear on the failure mode of the arch.The in-plane design method of the stable bearing capacity of two different section types of steel arch is established for practical application reference,the specific research contents are as follows:(1)The FE software ANSYS is used to establish the FE model,and according to the characteristics of the structure,the appropriate element,material constitutive relationship and analysis method are selected.In the elastic-plastic analysis,not only geometric nonlinearity is considered,but also the influence of geometric initial defects is considered.By comparing the results of shell element and beam element,the validity of beam element model is verified.(2)Based on the basic mechanics principle,the section bending,compression and shear stiffness of plate-tube-connected circular steel arch are deduced theoretically.Based on the in-plane classical elastic buckling theory of the arch,considering the influence of the shear deformation of the section,the in-plane elastic buckling load formula of the arch hinged at both ends is derived.For the arch with different geometric parameters,the results of FE and the elastic buckling load formula are compared.(3)According to the theory of steel structure stability,the limit conditions of avoiding the instability of connecting plate and chord are deduced before the global elastic buckling of the arch.The results are verified by the FE results.(4)Based on the design method of axial compression column,the regular slenderness ratio and stability coefficient are introduced,and based on the numerical results of large deflection elastic-plastic analysis,the stability curves of two different types of the plate-tube-connected circular steel arch are established,and the design formula of bearing capacity is given.On this basis,the bearing capacity of plate-tube-connected circular steel arch is proposed under the compression-bending.(5)Through numerical simulation,the characteristics of various local failures of the arch are analyzed comprehensively when shear force is considered.Based on the comprehensive consideration of bearing capacity,deformation and structural stiffness,a corresponding strength design formula is proposed for one of the local failures,and the strength design formula is compared with the FE results.