Study On Mechanic Of Concrete Filled CFRP-Steel Tube Column

The aim of this paper is to introduce this structure in three aspects: accomplished work, the mechanics of short columns and long columns.In the first part the background and the states of study on the CFCST(concrete filled CFRP steel tube) are introduced simply; there are experiment and theoretical analysis on the mechanics of the CFCST columns under axial compression in the chapter two.In the second part the mechanics of the short CFCST columns is investigated: Firstly the ultimate strength of CFCST is obtained after the steel tube is plastic with the theory of Hencky's plasticity. The equation is derived for estimating the strengths of the system in the case CFRP-sheet break; At the same time the hoop force between steel tube and concrete is ascertained. The concept of the equivalent hoop force is cited with the effect of slenderness and eccentricity ratio. On the basis of these theories the balanceable equations between forces and moment deduced stabilized load capacity; the eccentricity ratio coefficient and slendemess ratio coefficient are put forwards and the safe coefficient on the CFST is revised to deduce load capacity of the CFCST.In the numerical simulation based on the constitutive relations of concrete and steel tube of the CFST the constitutive relations of the CFRP, steel and concrete are put forwards. The short CFCST columns under axial loading are analyzed by using finite element software ANSYS and their loading-strain curves are obtained. These curves agree with experimental curves.In the third part the theoretical and experimental analysis on the long CFCST columns are investigated. The relation and difference between short CFCST column and short CFST column are studied through these two structures experiment, and the experiment of long CFCST column under axial compression were carried on; On these basis mechanical properties and the increment ratio of load bearing capacity of the concentrically compressed the CFST columns due to CFRP are studied; The influence of slenderness ratio on the load bearing capacity of the specimens is analyzed; The equation is derived for estimating the stability strengths of the system and the calculated results accorded with the text results .