The flexural rehabilitation of reinforced concrete beams by the use of prestressed advanced composite plates

The flexural strengthening of reinforced or prestressed concrete beams by external plate bonding has proved to be an effective and convenient technique in applications worldwide. If advanced fibre-reinforced composite plates are to be utilised as the strengthening medium, then a possible extension to the technique is that of pretensioning the plate prior to bonding to the concrete member. Some of the experimental work carried out in a current investigation at the University of Surrey on the structural behaviour of beams strengthened in this way is detailed in this publication. The prestressing technique employed was developed and refined on smaller-scale 1.0 m length specimens before being applied to larger 2.3 m length beams. This technique is described before results obtained during the application and release of the prestress and subsequent monotonic testing to failure of the strengthened beams are presented. Comparisons are made with beams externally reinforced with a plate unstressed at the time of bonding. The main conclusions drawn from the work are noted at the end of the paper and these indicate that the technique of prestressing advanced composite plates prior to bonding to reinforced concrete beams has the potential to provide a more efficient solution to strengthening problems. (C) 1998 Elsevier Science Ltd. All rights reserved