Flexural strengthening of RC continuous beams using CFRP laminates

This paper presents test results at failure of 16 reinforced concrete (RC) continuous beams with different arrangements of internal steel bars and external carbon fibre reinforced polymer (CFRP) laminates. All test specimens had the same geometrical dimensions and were classified into three groups according to the amount of internal steel reinforcement. Each group included one unstrengthened control beam designed to fail in flexure. Different parameters including the length, thickness, position and form of the CFRP laminates were investigated. Three failure modes of beams with external CFRP laminates were observed, namely laminate rupture, laminate separation and peeling failure of the concrete cover attached to the laminate. The ductility of all strengthened beams was reduced compared with that of the respective unstrengthened control beam. Simplified methods for estimating the flexural load capacity and the interface shear stresses between the adhesive and concrete at failure of beams tested are presented. Comparisons between results from experiments and those obtained from the simplified methods show that most beams were close to achieving their full flexural capacity and the longitudinal elastic shear stresses at the adhesive/concrete interface calculated at beam failure conformed to the limiting value recommended in the Concrete Society Technical Report 55. (C) 2003 Published by Elsevier Ltd.