Research On Behaviour Of Concrete-Filled Thin-Walled Steel Tube Under Axial Compression

The thin-walled steel tubes which are adopted in the concrete-filled steel tubeengineering are able to economize steel materials and lower the cost of theengineering. But the capacity of concrete-filled thin-walled steel tubularcolumns(CFTST) of which the D/t(a/t) ratio is relatively large is less than the sum ofcapacity of the two materials, because the tubular will buckle partly before the actionis equal to the ultimate capacity. So we must know rightly the capability of CFTSTsubjected to axial compressive force. Moreover, in order to use widely CFTST in theactual engineering, we must take reasonable measures to aviod or put off the bucklingof part of the tube. This paper put forward, the study of CFTST with annular hoop baris just an viable method to solve the problem.This paper study CFTST subjected to axial compressive force, and review theinfluence of its capacity because of the factors including D/t(a/t) ratio, L/D ratio,material strength and annular hoop bar etc. The specimens include concrete-filledcircular steel tubular columns which are analyzed primarily and square columns. Thispaper describes the phenomenon of experiment and the form of collapse of thespecimens, then in greater detail analyses the ultimate capacity of the specimens, thestrain of column, tubular and annular hoop bar, and the stress-strain relationship ofconcrete filled in the tube. Based on the experiment, the mechanical properties ofCFTST are further investigated by the non-linear finite element analysis program.According to the data of the experiment, the strength calculation formula of CFTSTsubjected to axial compression is presented by the regressive analysis, And theaccurately analytic strength formula of CFTST under axial compression is advancedbased on the related theories.