Ultimate response of RC beams strengthened with CFRP plates

Poststrengthening and retrofitting is a growing reality, as existing structures are required to meet the demands of modem society. Apart from the need to increase load capacity, upgrading of a structure may be necessitated through deterioration of the structure by corrosion or accidental damage, a change in the structural system, or to rectify initial design and construction faults. A commonly observed mode of failure for beams strengthened using carbon-fiber-reinforced polymer composite material plates is one due to the plate peeling off prematurely and unpredictably at relatively low magnitudes of applied loading. End plate anchorages and long unanchored plate lengths, which can add significantly to the overall cost of a strengthening solution, overcome this problem. This paper presents the results of flexural tests on ten reinforced concrete beams strengthened with different plate configurations. A strain compatibility and force equilibrium method of analysis, coupled with an empirical rule derived from the test data, is demonstrated to be effective in predicting the ultimate response of simply supported beams in bending with and without end plate anchorages and irrespective of plate length.