Theoretical Analysis Of Mechanical Properties Of Double Spatial Steel Frame Concrete Biased Short Columns

The existing research shows that the spatial steel frame makes the core concrete in the three-direction stress state,which improves the mechanical properties of the concrete,so that the spatial steel frame concrete short column has good bearing capacity and ductility.In order to further improve the performance of the spatial steel frame concrete columns,this paper proposes a new type of composite column—double spatial steel frame concrete short columns,which is a spatial steel frame built into the spatial steel frame concrete short column to form a combined column with double restraint.In this paper,a comprehensive theoretical analysis of the eccentric behavior of double-spatial steel frame concrete short columns is carried out.1)Analysis of mechanical mechanism of double-spatial steel frame concrete short columnsAccording to the confined concrete constitutive model proposed by Mander and the constitutive relation model of confined concrete in spatial steel frame,the force mechanism of double-spatial steel frame concrete short column is proposed.2)Nonlinear finite element analysis of double-spatial steel frame concrete biased short columnsThe nonlinear finite element analysis model of double-spatial steel frame concrete short column was established by ABAQUS finite element analysis software.Based on the agreement with the existing tests,the eccentricity,the inner space steel frame steel distribution ratio(ρ_s1),the outer space steel The frame steel ratio(ρ_s2),the embedded steel frame restraint influence coefficient(λ_v1)and the outer steel frame restraint influence coefficient(λ_v2)are the design parameters.The double-spatial steel frame concrete bias short column model is established and compared.The results show that with the decrease of eccentricity,the increase of the length of the inner and outer steel skeleton angle steel,the increase of the thickness of the inner and outer steel skeleton angle steel,the decrease of the inner and outer transverse strip spacing,the increase of the inner and outer horizontal strip width,and the improvement of concrete strength.As the strength of the steel is increased,the bearing capacity of the test piece is improved.3)N_u-M_u correlation equation for eccentric compression of double-spatial steel frame concrete short columnsBased on the existing experimental research and calculation methods,99 spatial steel frame concrete biased short column models were designed and analyzed.The N_u-M_u correlation equation of spatial steel frame concrete biased short columns was established.The results and experimental data were obtained.Good agreement,can provide reference for practical projects.Based on the N_u-M_u correlation equation of the spatial steel frame concrete biased short column,the N_u-M_u correlation equation of the eccentric compression of the double-spatial steel frame concrete short column is further proposed.4)Calculation method of bearing capacity of double-spatial steel frame concrete biased short columnBased on the theoretical analysis,three kinds of calculation models for the bearing capacity of three-spatial steel frame concrete biased short columns are established.The calculated values agree well with the experimental values,which can provide a basis for the calculation of the bias bearing capacity of the double-spatial steel frame concrete short columns.