Experimental Study On Seismic Behavior Of Spatial Steel Frame SRC Concrete Columns

In recent years,with the increasing number of high-rise building layers,the requirements of the seismic performance of the columns are getting higher and higher.How to improve the bearing capacity and seismic performance of the columns while reducing the cross section of the columns is a hot issue.In this paper,a new type of steel-concrete combination column is proposed,which is the spatial steel frame steel reinforced concrete column by using the constraints of the spatial steel frame and the steel pipe on the core concrete.The structure of the structure is in the outer space steel frame instead of ordinary steel cage,while the inside of the different forms of steel and pouring concrete composition of the composition of the column.Based on the experimental study and the finite element analysis of the seven spatial steel frame-steel reinforced concrete columns under low cyclic loading,the seismic performance of this new type of composite column is studied.Based on the theoretical analysis,the formula for calculating the ultimate bearing capacity of spatial steel frame-steel reinforced concrete columns with bias space has been deduced.Six concrete frames of spatial steel frame-steel reinforced concrete columns and one concrete column with external steel frame were designed with the steel content(angle length),axial compression ratio and different steel forms as the parameters.The experimental data were studied under low cyclic loading.During the test,the data such as the destroy pattern,the development of the crack,the strain of the measuring point and the ultimate bearing capacity were mainly observed and recorded.The seismic performance indexes such as hysteresis curve,skeleton curve,stiffness degradation curve and energy consumption performance curve are analyzed.The results show that increasing the limb length(increasing the steel content)and reducing the axial compression ratio can improve the deformation capacity and ultimate bearing capacity of the space steel frame-steel reinforced concrete column.The spatial steel frame-steel reinforced concrete columns all show typical curved failure type,and the hysteresis curve is full and no obvious shrinkage,and the ultimate bearing capacity is large and the seismic performance is good.Nonlinear finite element model of spatial steel frame-steel reinforced concrete columns were established by large-scale finite element software ABAQUS.On the basis of the verification of the test specimen,the axial compression ratio,the internal and external reinforcement ratio,the internal and external stirrer rate,the thickness of the square steel pipe and so on,which are taken as parameters and model analysis.The simulation results show that it is also feasible to improve the mechanical behavior of the spatial steel frame-steel reinforced concrete column by increasing the width of the space steel frame,reducing the spacing between the spatial steel frames and increasing the thickness of the steel pipe.And the main factors of the mechanical behavior of the spatial steel frame-steel reinforced concrete column are obtained: the comprehensive impact parameters.Based on the experimental study and the mechanism analysis,the constraint effect of the square steel pipe on the core concrete and the restraint effect of the spatial steel frame on the concrete are studied.Two different constitutive relations model of concrete are obtained.Secondly,the calculation formula of eccentric compression ultimate bearing capacity of this new type of space steel frame-steel reinforced concrete column was deduced by superimposed method.The results of the theoretical formula were assord with the experimental data,which can provide the basis for the calculation of the space steel frame-steel reinforced concrete column.