Strengthening of RC Beams with External Post-Tensioned CFRP Tendons


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Title: Strengthening of RC Beams with External Post-Tensioned CFRP Tendons

Author(s): A. Elrefai, J. West, and K. Soudki

Publication: Special Publication

Volume: 245


Appears on pages(s): 123-142

Keywords: external prestressing; flexure; FRP; overloading; post-tensioning; strengthening; tendon; unbonded

Date: 4/1/2007

The monotonic flexural performance of reinforced concrete beams strengthened with external post-tensioned CFRP tendons was investigated. Variables include straight and double draped tendon profiles, and two post-tensioning conditions: at service load (50% of the yielding capacity - in-service beam) or after overloading to twice the steel reinforcement yield strain (overloaded beam). The beams were tested to failure in four-point bending. Experimental results indicated that the tendon profiles investigated did not affect the beam behavior. Overloading of the beam prior to post-tensioning had a significant effect on the deflection capacity of the beam, with a slight effect on the yield and ultimate capacities. A strain reduction approach, developed previously for unbonded steel tendons, was extended to model the beam behavior. The loading history of the beam prior to strengthening was explicitly accounted for in the model. The analytical predictions showed good agreement with the experimental values.