Tests on Axially Loaded Concrete Columns Confined by Fiber Reinforced Polymer Sheet Wrapping

Wrapping of columns by means of FRP (Fiber Reinforced Polymer) reinforcement enhances the structural behavior of concrete columns considerably. At the Magnel Laboratory for Concrete Research a test program is set-up to evaluate some specific problems in the modeling of FRP confined concrete, i.e., effective circumferential FRP failure strain and effect of increasing confining action. Parameters studies are FRP type, bonded or unbonded wrapping application, column shape and strengthening lay-out. Both wrapped cylinders and wrapped columns are investigated. An analytical verification of the test results is performed according to different models. From the test results obtained so far, the efficiency of this strengthening technique has been demonstrated, both in terms of structural performance and ease-of-application. Quality of the application (voids, protrusion, etc.) and the wrapping concept (bonded or unbonded, partial wrapping, etc.) influence the strengthening effect.