Compressive behaviour of CFS strengthened concrete specimens with various cross-sectional shapes and laminations

Abstract

The repairing technique of surface wrapping concrete structural members using fibre composite sheets has been widely used. Therefore, significant research efforts have concentrated on understanding the mechanism of concrete members wrapped with fibre composite sheets for lateral confinement. In order to apply the carbon fibre sheet (CFS) surface wrapping technique in retrofitting of aged concrete column structures, the effect of cross-sectional shape on concrete columns with CFS wrapping has been studied. In this research, compression tests have been performed on CFS reinforced concrete specimens with various cross-sectional shapes (i.e. square, octagonal, and circular) and lamination schemes (i.e. [0/0/0/0], [90/90/90/90], [0/45/−45/90], and [0/90/90/0]). The specimens were tested in order to understand the confinement effect of CFS from square to circular members. The test results showed that the strength and ductility of the specimens depend on the CFS fibre direction. Also, the specimens with octagonal cross-sectional shape behaved in a similar manner to the circular specimens, indicating that the retrofitting and strengthening of square columns can be effectively performed by converting them into octagonal columns. Based on the research results, a new repairing method of converting a square cross-sectional column to an octagonal one for CFS surface wrapping is currently being studied.