The behavior of reinforced concrete beams strengthened with various types of fiber reinforced polymer (FRP) laminates is presented. The experimental program included strengthening and testing 24 simply supported rectangular cross section beams. Each beam was initially loaded above its cracking load. The cracked beams were strengthened with FRP laminates and then tested until complete failure. Five available strengthening systems of various types of carbon/glass fiber reinforced polymer (CFRP/GFRP) strengthening materials were used. These materials included two types of CFRP sheets, bi- and unidirectional GFRP sheets, and CFRP plates. The effects of strengthening on deflection, failure load and failure mode, strain, and beam ductility are discussed. In addition, the influence of different numbers of FRP layers, type of epoxy, and strengthening pattern on the behavior of beams was examined. The ratio of absorbed energy at failure to total energy, or energy ratio, was used as a measure of beam ductility. It is concluded that, in addition to the longitudinal layers, the fibers oriented in the vertical direction forming a U-shape around the beam cross section significantly reduce beam deflections and increase beam load carrying capacity. Furthermore, the presence of vertical and horizontal sheets, together with a proper epoxy, can lead to a doubling of the ultimate load carrying capacity of the beam. However, all the strengthened beams experienced brittle failure, mandating a higher factor of safety in design.


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  • Accession Number: 00778159
  • Record Type: Publication
  • Contract Numbers: OGP0042033
  • Files: TRIS
  • Created Date: Nov 16 1999 12:00AM