Bending Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Laminates and Subjected to Freeze-Thaw Cycles

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Title: Bending Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Laminates and Subjected to Freeze-Thaw Cycles

Author(s): M. del Mar Lopez, A. E. Naaman, and R. D. Till

Publication: Special Publication

Volume: 188

Issue:

Appears on pages(s): 559-576

Keywords: beams; carbon; fiber; freeze-thaw; laminates; plates; polymers; reinforced; ultimate deflection

Date: 8/1/1999

Abstract:
Thirty-six concrete beams strengthened with glued-on CFRP laminates were tested in bending after being subjected to different numbers of freeze-thaw (F.T.) cycles. In order to evaluate a possible deterioration of the interface bond between the concrete and the CFRP laminate, the development length of the glued-on plate was purposely made smaller than the required value. Parameters investigated were: 1) different strengthening systems; 2) precracking of the beams, prior to strengthening; and 3) number of freeze-thaw cycles (0, 100, 200 and 300). For each number of freeze-thaw cycles three control specimens (RC beams with no externally glued-on CFRP laminates) were also tested. It was generally observed that both the moment capacity and the ultimate deflection decreased with an increase in the number of freeze-thaw cycles. The rate of decrease was larger for precracked than for non-precracked beams. For design purposes the value of the horizontal interfacial shear strength can be taken conservatively as 0.17 ÷f’c.