Axial compressive behavior of grouted concrete block masonry columns confined by CFRP jackets

Confining existing concrete and masonry columns by Carbon Fiber Reinforced Polymers (CFRP) is a beneficial method for enhancing the column axial capacity and ductility. This paper presents an experimental investigation of the CFRP confinement influence on the uniaxial compression stress-strain behavior of concrete block masonry columns. Scaled fully grouted concrete block masonry columns, with a square cross section, were confined by continuous CFRP jackets and tested under concentric axial loading up to failure. The results indicate that CFRP enhances the ultimate axial strain and the axial load capacity by up to 281% and 79%, respectively compared to unreinforced columns. In this study, the effect of corner radius and the thickness of CFRP jackets are investigated. Special attention was also given to the effective tensile strain in the CFRP jackets. Finally, the CNR-DT 200 R1 confinement model, the only guide addressing strengthening masonry columns with external FRP composites, was assessed and refined equation is proposed.