Effect of shape modification on the confinement effectiveness of CFRP strengthened square concrete compression members: Experimental study

The effect of shape modification on the confinement effectiveness of CFRP strengthened square section concrete members experimentally investigated. Parameters examined were: (a) the type of shape modification namely; edges rounding, circularizing and curvilinearzing square section, (b) the strengthening configuration (i.e. fully and partially strengthening configurations), and (c) the number of CFRP layers (1 and 2 layers). A total of 32 specimens were prepared, strengthened, and tested under uniaxial compression loading. It was mainly found that; (a) the circularized shape modification showed the highest compressive strength increase than the curvilinearized and edges rounded shape modification strengthened specimens (b) the full confinement strengthening configuration was more effective than the partial confinement configuration in enhancing the compressive strength (c) doubling the number of CFRP layers (from 1 to 2 layers) resulted in an approximately proportional increase in the compressive strength. Furthermore, modifying the square to circular and curvilinear section resulted in considerable enhancement in the energy absorption compared to the edges rounded confined specimens. Additionally, the deformation capacity of the strengthened specimens increased compared to non-strengthened specimens and also was sensitive to the number of CFRP layers and shape modification. Finally, the failure mode of strengthened specimens was not affected by the type of shape modification.