External jacket of FRP wire for confining concrete and its advantages

This study investigates the effectiveness of FRP wire to confine concrete. For this purpose, axial compressive tests are conducted with three parameters, peak strength of concrete, confining amount of FRP wire, and epoxy application. The behavior of the FRP-wire confined concrete is examined in the axial and circumferential directions as well as in terms of volumetric strain. Each behavior is discussed according to the stiffness ratio of the confining FRP wire to concrete. Moreover, the confinement effectiveness of the FRP wire is estimated using the actual rupture strain of the FRP wire as well as the ultimate tensile strain. Both cases show slightly larger effectiveness than that of FRP sheet confined concrete. The external jacket of the FRP wire increases the peak strength satisfactory and restrains volumetric expansion when the stiffness ratio of the jacket is sufficiently large. The failure of the FRP wire confined concrete occurs at the mid-height of the cylinder. Furthermore, this study investigates the behavior of partially confined concrete exhibiting smaller peak strength compared to the corresponding fully confined specimen, as it appears to have a smaller stiffness ratio.