Ultimate Bearing Capacity of Concrete-filled Circular Steel Tubular Long Columns with Axial Compression

Considering the intermediate principal stress effect of the steel tube on the circumferential tension and longitudinal compression based on the twin shear unified strength theory,a formula of bearing capacity of steel tube was established.Meanwhile,in terms of the unified strength criterion of concrete and avoiding uncertainty analysis of effect factor of circumferential compression in concrete failure criterion,the formula of bearing capacity of core concrete was established.And then by splicing the bearing capacity of short concrete-filled steel tube(CFST),the formula of bearing capacity was formed.Based on it,through elastic modulus theory,the stability effect factor of concrete-filled steel tubular long columns was deduced and then the formula of its ultimate bearing capacity was built.The results show that by altering weighted parameter value,the bearing capacity of concrete-filled steel tube is changed.The calculations are all agree well with the experiment results through comparing with the experimental values of related references.