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Features and Benefits
Repair
FRP
composite systems can be used to repair damaged concrete structures. The
FRP is used in combination with resin crack injection, cementitous repair
mortars, epoxy grouts, etc., to repair the section and restore it to
pre-damaged load ratings. Repair of concrete structures caused by
corroding steel rebar can be accomplished provided the corroded elements
are repaired or replaced and the source of corrosion is addressed. The
repair of any element in a structure must be approached as
project-specific. The type of composite, the number of layers, the
orientation of fibers, and the preliminary work and surface preparation
all depend on the design goals and type of structural element as
determined by the project.
Strengthening
FRP composite systems can be used to strengthen undamaged concrete
structures that require greater load capacity due to functional changes,
additional loads, code changes or other reasons. The FRP is placed on
tensile surfaces in a manner similar to steel plate bonding for
strengthening or embedded into saw cut grooves near the concrete surface.
FRP composite systems can add shear and flexural strength to beams and
slabs for both positive and negative moment conditions. Strengthening of
existing concrete structural members with FRP composites is accomplished
by utilizing the tensile strength and stiffness of the composite and the
strain compatibility of the composite to the existing member. The design
must include proper selection of the adhesive used to bond the FRP
reinforcement to the surface of the concrete to be strengthened. As in
repair, the type of composite, the number of layers, the orientation of
fibers, and the preliminary work and surface preparation all depend on the
design goals and type of structural element as determined by the project.
Seismic
Retrofit
FRP composite systems have been used extensively in seismic zones for
confinement of concrete columns and walls. A number of FRP systems have
been qualified for use by State DOT’s for wrapping circular and
rectangular bridge columns. Improvements in ductility factors of up to 10
fold have been realized through the use of FRP column wrapping. Specific
FRP systems, offered by some of the manufacturers referenced below,
address seismic requirements according to the load capacities anticipated
and geometric considerations of the building structure. In addition, FRP
systems can be used for stabilizing hollow clay tile, brick and other
unreinforced and lightly reinforced masonry walls in life-safety
applications where vital egress and exit paths in buildings are required.
Codes and Specifications
The designer or end-user considering the use of FRP composite systems for
the repair, strengthening or seismic upgrade of existing structures should
reference:
USA
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ACI 440.2R-02,
Guide for the Design and Construction of Externally Bonded FRP
Systems for Strengthening Concrete Structures, American Concrete
Institute, 2002.
Europe
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Europe fib
Bulletin 14,
Externally Bonded FRP Reinforcement for RC Structures,
Federation
Internationale du Beton, 2001, ISSN 1562-3610.
Canada
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CSA S806-02,
Design
and Construction of Building Components with Fiber-Reinforced Polymers,
Canadian Standards Association, May 2002, ISBN 1-55324-853-8.
Design Guide Manuals
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FRP Systems: Wet Lay-up
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