Finite Element Simulations of the CFRP Retrofitted Hollow Square Columns

This article describes the finite element analysis of concrete columns with a hollow square reinforced which restricted with a square Carbon-Fiber-Reinforced polymer (CFRP) tube.  In this study, about sixteen square hollow core columns were investigated. These columns were classified into four sets. The set number one was the reference set which involved four unconfined reinforced columns with traditional steel helices and longitudinal steel bars. The columns of the 2nd category have a similar configuration as the set number one except that these columns were restricted outwardly by the CFRP tube. The columns of the set number were restricted outwardly by a CFRP tube and restricted inwardly by a steel tube. Finally, the columns of the 4th category do not have a steel reinforcement where they produced with only an outer CFRP tube and an inner steel tube. These columns were exposed to various loading conditions: concentric, eccentric (22 and 44) mm, and four bendings' points. It was investigated that the CFRP tube confinement faintly improved the columns’ strength. Moreover, the use of a steel tube as inner confinement in the columns with a hollow section led to improve the structural performance and ductility.