Volumetric Response of FRP-Confined Full-Scale RC Columns

The external confinement of reinforced concrete (RC) columns by means of externally bonded fiber reinforced polymer (FRP) laminates is a well established technique for strengthening and retrofitting purposes. This paper presents a pilot research that includes laboratory testing of full-scale square and rectangular (with side-aspect ratio smaller than 1.5) RC columns externally confined with glass and basalt-glass FRP laminates and subjected to pure axial load. Specimens that are representative of full-scale building columns were designed according to a dated ACI 318 code (i.e., prior to 1970) for gravity loads only. The study was conducted to investigate how the external confinement affects peak axial strength and deformation of a prismatic RC column. The results showed that the FRP confinement increases concrete axial strength, but it is more effective in enhancing concrete strain capacity.