Research On Compression Performance Of Centrifugal Concrete Filled Steel Tube

As an important branch of concrete-filled steel tube,the centrifugal concrete filled steel tube(CCFST)not only makes full use of the material properties of steel and concrete,but also makes up for the defects of each own and shows excellent mechanical properties.Therefore,it is of great practical significance in the study of the compressive mechanical properties of CCFST.Based on the finite element software ABAQUS 6.11 and the relevant experiment on axial bearing properties of CCFST,the compression resistance capability of CCFST were analyzed in thispaper.Firstly,the finite element models of CCFST,which were consistent with the tested component on the size,were established by adopting four kinds of representative material constitutive relation models.On the basis of the finite element results and the experiment results,the applicable scope of different material constitutive relation models in the analysis of CCFST were researched.Then,the influence of thickness of steel pipe,the strength of concrete and ratio of hollow on the axial bearing property of CCFST were analyzed by the numerical analysis.The influence of thickness of steel pipe,eccentricity and ratio of hollow on the eccentric bearing property of CCFST were analyzed by the numerical analysis.Finally,based on the unified theory of concrete filled steel tube and the formula for calculating the bearing capacity of concrete filled steel tubular columns under eccentric loading,the calculation formula of CCFST under eccentric compression was deduced.The followings can be concluded through the study on CCFST: different material constitutive relation models have different scope of application.Mander model is suitable for circular section,Liuwei model is suitable for square cross section.Neither Han Linhai model nor Zhong Shantong model is suitable for circular section and square cross section.The thickness of steel pipe has a relatively obvious influence on the axial pressure performance of CCFST and the strength of concrete has a weak influence.Large hollow ratio can significantly weaken the axial compression bearing capacity of CCFST.When the hollow ratio decreases to a certain value,the further decreased of the hollow ratio has a weak influence on the increasing of the axial compression bearing capacity of CCFST.The eccentricity has a relatively obvious influence on the mechanical performance of CCFST under eccentric loading and the hollow ratio has a weak influence.It has not obvious influence on the elastic stiffnessof CCFST when increasing the thickness of steel pipe or decreasing the hollow ratio,but it has a certain influence on the ductility of the member.As for improving the ductility of the member,the increasing of the thickness of steel pipe is superior to decrease the hollow ratio.The propose formula for calculating the ultimate bearing capacity for bias has good agreement with the numerical analysis results.