Chris Burgoyne and Miguel Morais
Department of Engineering, University of Cambridge,
Cambridge, UK
The main problem in the use of fibre
reinforced plastic (FRP) materials for prestressing beams is their linear elastic
behaviour; this results in a brittle structural failure. By enhancing the
plastic capacity of concrete and by using it, we can increase the ductility of
our structures. An analytical study is presented that shows that the same
values of energy dissipation can be achieved using steel and Fibre Reinforced
Plastic
(FRP) prestressed concrete sections, provided we used over-reinforced
beams with confined concrete.
Interest in the use of Fibre
Reinforced Plastics (FRP) as reinforcement material started in the early 1980’s
due to corrosion problems with steel, particularly in hot and wet or saline
environments. Small bridge sections and full bridges have been built on a trial
basis in Canada, Japan and Germany (Grace at al, 1998) as well
as many other places.
The main advantages in the use of Fibre
Reinforced Plastic (FRP) prestressing reinforcement are high resistance to
corrosion, high strength-to-weight ratio, good fatigue resistance and low
relaxation. The main disadvantages are high cost in comparison to steel; lack
of design codes, brittle behaviour resulting in reduced structural ductility
and lack of understanding of the behaviour of Fibre Reinforced Plastic (FRP)
reinforced continuous structures.
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