HM CFRP Strengthening System

The carbon fibers used in this study were the DIALEAD K63712 high modulus pitch based carbon fibers produced by Mitsubishi Chemical Functional Products Inc. The fibers were pultruded into 4mm thick, 100mm wide laminates by Epsilon Composite Inc., a French pultrusion company. The modulus of elasticity and ultimate strain of the strips which were reported by the manufacturer are 460 GPa and 0.00334 respectively. The laminates have a fiber volume fraction of 70 percent and were fabricated with a glass fiber peel ply on both faces to minimize the need for surface preparation of the composite material. The strips were bonded to the tension flange of the steel beams using the Spabond 345 two part epoxy adhesive with the fast hardener which is manufactured by SP Systems North America. This adhesive was selected from six adhesives in a previous phase of this research (Schnerch, 2005). The tension flange of the steel beam was grit blasted immediately prior to installation of the strengthening system to remove rust and mill scale from the surface. The surface was subsequently cleaned by air blowing and solvent wiping. After the CFRP strips were installed a wooden clamping system was applied for at least 12 hours until the adhesive had thoroughly set. The adhesive was allowed to cure for at least one week prior to testing.