Reference Type: Journal Article Record Number: 1 Author: LI, G. C., Di, C. Y., Tian , L. and Fang, C. Year: 2012 Title: Nonlinear finite element analysis on long columns of high-strength concrete-filled square steel tube with inner cfrp circular tube under axial load Journal: Advanced Steel Construction Volume: 9 Issue: 2 Pages: 15 Start Page: 124 Short Title: Nonlinear finite element analysis on long columns of high-strength concrete-filled square steel tube with inner cfrp circular tube under axial load DOI: 10.18057/IJASC.2013.9.2.3 Keywords: ABAQUS finite element, inner CFRP circular tube, axial compression, working mechanism, boundary slenderness ratio. Abstract: The concrete-filled square steel tubular structure has been applied wildly in the practical projects around the world. To install CFRP into the column is beneficial not only to overcome the disadvantages of the high-strength concrete, but also to improve the bearing capacity and the stability of the concrete-filled square steel tube. This paper adopts finite element analysis software ABAQUS 6.7 to make nonlinear finite element analysis on a large number of long columns of high-strength concrete-filled square steel tube with inner CFRP circular tube subjected to axial compression. The analysis results are verified by the tests. In addition, the load-axial strain curves in the whole process are calculated and analyzed, and they are divided into 4 segments: elastic phase, plastic phase, descending phase and rebound phase. Based on the curves of load-axial strain, the stresses analysis on the core concrete, CFRP tube and square steel tube are conducted. The results of finite element simulation analysis show the destruction of long columns subjected to axial compression are all buckling failure. It indicates that slenderness ratios are the key to decide the type of buckling failure for long columns under axial compressive loading. The boundary slenderness ratio between elastic buckling and plastic buckling is discussed. Author Address: Professor, School of Civil Engineering, Shenyang Jianzhu University, Shenyang, China