C.J. Burgoyne and I.
Balafas
Engineering Department, University
of Cambridge, Cambridge, UK
Research on the application of
fibre-reinforced plastics (FRPs) in concrete structures has been extensive.
Fibre-reinforced plastics (FRPs) are a suitable alternative reinforcing
material but their high initial cost hinders their use, partly due to the high
cost of prototype batches. The high cost means little demand, so there is
little incentive for the composites industry to invest in the civil engineering
market. This paper arises from a study to investigate the various cost
interactions in the market for fibre-reinforced plastic (FRP) reinforced or
prestressed structures.
While most of the technical
questions concerning structural integrity of concrete structures prestressed
with fibre reinforced plastic bars have already been solved, their application
is limited to prototype structures due to their high initial cost. The paper
proposes a method for selecting structural dimensions that are optimised with
respect to cost. By observing the sensitivity of the optimum solution to
various factors, more efficient ways to use those materials in structures can
be found.
One of the drawbacks in design with
fibre-reinforced plastics (FRPs) is their brittle nature. Plastic behaviour
gives warning of failure, and in indeterminate structures, moment
redistribution can occur. In prestressed concrete structures with FRP tendons,
plastic deformation can come from concrete when properly confined. Recent work
on fibre-reinforced plastic (FRP) prestressed beams confined in the compression
zone with aramid spirals showed extensive non-linear characteristics in the
load deflection curve. By adjusting the bond conditions between concrete and
reinforcement, the desired concrete crushing failure mode can be achieved.
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