Analysis On Structural Stressing State Characteristics Of CFST Arch Models Under Spatial Loads

In existing analysis of concrete-filled steel tube(CFST)arch structures,studies on in-plane mechanical properties are much more than those on spatial stabili ties.Their basic theories mainly refer to the theories of CFST columns.Due to the restrictive factors existing in theories and methods,arches with specific parameters and structural forms can always obtain ideal analysis results while others will have large calculation errors or even the method will not be applicable.It indicates that there is no systematic and unified understanding of mechanical properties and failure process of arch structures,and many structural working behaviors are still not revealed.In order to reveal the working behavior characteristics of CFST arches under spatial loads,this paper uses the method of modeling structural stressing state to analyze the experimental data of single tube CFST arches.The main works of this paper includes:(1)The method of modeling structural stressing state is systematically elaborated.The generalized strain energy density(GSED),as the stressing state characteristic parameter,is proposed to model experimental data for describing the structural stressing state mode.The Mann-Kendall criterion is also used to detect the mutation of structural stressing state and to reveal/determine the starting point of structural failure.It is defined as the failure load for structural design rather than the ultimate load.(2)The spatial working behavior of a single tube CFST arch is analyzed,and the stressing state characteristic curve is obtained by GSED.The elastic-plastic branching point and the failure load of the curve are identified.When the load exceeds the failure load,the arch enters the unstable failure stage and is no longer suitable for load bearing.The rationality of the failure load is validated by analyzing the change trend of structural response parameters(strain,displacement),and structural stressing state submodes constructed by internal forces.(3)The numerical shape function method,which combines the simulation and interpolation,is used to achieve more accurate interpolation values of experimental data and obtain more abundant test information.By interpolating the limited measured data of the arch with this method,the stress/strain fields of each section and the distribution modes of internal forces can be obtained,so that the mechanical characteristics of the structure can be thoroughly analyzed,and the rationality of the failure load can be further verified.(4)The working behavior of a single tube CFST arch under in-plane uniform loads is analyzed.Based on the method of modeling structural stressing state,the similarities and differences between the stressing state characteristics of this arch with the arch under spatial loads are compared.In practical design,the lateral loads should be limited so that the arch can be subjected to vertical loads as possible,so as to improve the actual bearing capacity of the arch.