| With the increase of the height of the tall building,the demand for the bearing capacity and the ductility of the column is becoming more and more high,and a new type of composite column is needed.At present,many scholars have studies the steel tube concrete columns with the built-in steel.Based on the constrain of spatial steel frame and circular steel tube to concrete,this paper puts forward a new type of embedded steel in the steel tube composite column——circular steel tube concrete column filled spatial steel frame.This structure is a double constrain composite column formed in the circular steel pipe with spatial steel frame formed by the angle steel and steel strip.Based on the experimental study and the finite element analysis of the five circular steel tube concrete columns filled spatial steel frame and a circular steel tube concrete column under axial loading,the axial performance of this new type of composite column is studied.And the formula for calculating the ultimate bearing capacity of the composite column has been deduced.With the diameter and thickness ratio of the outer circular steel tube and the spacing between steel strips as the parameters,five circular steel tube concrete columns filled spatial steel frame and a steel tube concrete column were designed and tested.The test results show that the circular steel tube concrete columns filled spatial steel frame has higher load carrying capacity than the ordinary circular steel tube concrete column and have better ductility.The peak load of the circular steel tube concrete columns filled spatial steel frame was increased,as the diameter and thickness ratio of the outer circular steel tube increased and the spacing between steel strips decreased.Nonlinear finite element model of circular steel tube concrete columns filled spatial steel frame were established by large-scale finite element software ABAQUS.First,the correctness of the model is verified on the basis of the existing experiments.Then,taking the diameter and thickness ratio of circular steel tube,angle steel length,angle steel thickness,steel strip spacing and steel strip width as parameters,the same method is used to establish the circular steel tube concrete columns filled spatial steel frame.The results show that the bearing capacity and ductility of the specimens increase with the increase of the diameter thickness ratio of the circular steel pipe,the increase of the angle steel length,the increase of the angle steel thickness,the decrease of the steel strip spacing and the increased of the width of the steel strips.On the basis of experimental research and theoretical analysis,the ultimate bearing capacity of circular steel tube concrete columns filled spatial steel frame is derived by superposition method,which is in good agreement with the experimental data. |
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