Hoop fiber and surface matrix strain development on concrete members confined with FRCM composites

In this paper, the effectiveness of FRCM composites for the confinement of concrete specimens is studied. Concrete cylinders were confined using either carbon- or glass-FRCM jackets, and then tested monotonically under axial load. Performance of the system was evaluated in terms of gain in axial strength and ductility with respect to unconfined specimens. In addition, values of hoop strains recorded with strain gauges mounted on the fibers were compared to those obtained on the composite surface using a digital image correlation (DIC) system. Results show that carbon-FRCM jackets provide higher gain in axial strength than their glass-FRCM counterparts and have a higher fiber exploitation ratio. Measurement of hoop strains on composite surface were significantly higher than those recorded directly on the fibers using strain gauges, for both the FRCM-confinig systems.