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Designing with Composite Rebar
The mechanical
properties of FRP reinforcing bars differ from those of conventional steel
rebar in a number of areas. As a result, several issues arise in the
development of a design methodology for concrete structures reinforced
with such bars. The general design recommendations for flexural concrete
elements reinforced with FRP reinforcing bars are presented in ACI
440.1R-06 (2006), Guide for the Design and Construction of Structural Concrete
Reinforced with FRP Bars, as reported by the American Concrete
Institute (ACI) committee 440.
The design
philosophy adopted for FRP bars allows
consideration to be given to either FRP rupture or concrete crushing as
the mechanism that controls failure. It is based on limit states design
principles. An FRP reinforced concrete member is designed based on its
required strength, and then checked for fatigue endurance, creep rupture
endurance, and serviceability criteria. In most cases serviceability
criteria or fatigue and creep rupture endurance limits will control the
design.
Design engineers should consider the
appropriateness of reinforcing concrete with FRP bars, keeping in mind the
following basic points in their designs:
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Direct substitution of FRP bars in a
concrete member designed with steel bars is
not
possible in most cases. |
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Lower modulus of elasticity and shear
strength of composite rebars may limit the applications where FRP bar
can be utilized. |
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Glass FRP bar is limited to a maximum
sustained stress of 25% of the guaranteed design tensile strength. |
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Glass FRP bar applications are limited
to the reinforcement of concrete and should not be used as a prestressing or post-tensioning element. |
Design Codes/Guidelines
Extensive effort on an international level has resulted in
the development of codes and guidelines for FRP composite use in reinforced concrete. Existing publications currently
available for such use are as follows:
American Concrete Institute (ACI)
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ACI 440R-07 “Report on
Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures,”
ACI Committee 440, American Concrete Institute, Farmington Hills, Mich.,
(2007), 100p. |
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ACI 440.1R-06 “Guide for the Design
and Construction of Structural Concrete Reinforced with FRP Bars,” ACI Committee
440, American Concrete Institute, Farmington Hills, Mich., (2006), 44p. |
| ACI 440.5-08 "Specification for
Construction with Fiber-Reinforced Polymer Reinforcing Bars," ACI
Committee 440, American Concrete Institute, Farmington Hills, Mich.,
(2008), 5p. |
| ACI 440.6-08 "Specification for
Carbon and Glass Fiber-Reinforced Polymer Bar Materials for Concrete
Reinforcement," ACI Committee 440, American Concrete Institute,
Farmington Hills, Mich., (2008), 6p. |
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ACI 440.3R-04 "Guide for Test
Methods for Fiber Reinforced Polymers (FRP) for Reinforcing and
Strengthening Concrete Structures," ACI Committee 440, American Concrete
Institute, Farmington Hills, Mich., (2004), 40p. |
|
ACI 440.2R-08 "Guide for the Design and
Construction of Externally Bonded FRP Systems for Strengthening Concrete
Structures," ACI Committee 440, American Concrete
Institute, Farmington Hills, Mich., (2008), 76p. |
|
ACI 440.7R-10 "Guide for the Design and
Construction of Externally Bonded FRP Systems for Strengthening
Unreinforced Masonry Structures" ACI Committee 440, American Concrete
Institute, Farmington Hills, Mich., (2010), 46p. |
|
ACI 440.4R-04 "Prestressing Concrete
Stuctures with FRP Tendons," ACI Committee 440, American Concrete
Institute, Farmington Hills, Mich., (2004), 35p. |
Available from:
American Concrete Institute
www.concrete.org
American Association of State Highway
and Transportation Officials (AASHTO)
|
"LRFD Bridge Design Guide Specifications for
GFRP-Reinforced Concrete Bridge Decks and Traffic Railings," American
Association of State Highway and Transportation Officials, Washington,
D.C., (2009), 68p. |
Available
from: AASHTO
www.transportation.org
Canadian Standards
Association (CSA)
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CAN/CSA-S806-02 “Design and
Construction of Building Components with Fibre-Reinforced Polymers”,
Canadian Standards Association, Toronto, Ontario, Canada, (2007),
218p. |
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CAN/CSA-S6-06 “Canadian Highway Bridge
Design Code” Canadian Standards Association, Toronto, Ontario,
Canada,
(2006), 1078p. |
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CAN/CSA-S807-10 “Specification for Fibre-Reinforced
Polymers” Canadian Standards Association, Toronto, Ontario,
Canada,
(2010), 44p. |
Available from:
Canadian Standards Association
www.shopcsa.ca
Intelligent Sensing for Innovative
Structures - Canada (ISIS)
|
Design Manual No. 3, “Reinforcing Concrete Structures with
Fiber Reinforced Polymers”, Intelligent Sensing for Innovative
Structures Canada Corporation, Winnipeg, Manitoba, Canada, (2001), 158p. |
Available from:
ISIS
Canada
www.isiscanada.com
Japan
Society of Civil Engineers
|
Concrete Engineering Series 23, “Recommendation for Design and Construction of Concrete Structures
Using Continuous Fiber Reinforced Materials,” Research Committee on Continuous Fiber
Reinforcing Materials, Japan Society of Civil Engineers, Tokyo, Japan,
(1997), 325 p. |
International Federation for Structural
Concrete
|
fib Bulletin No. 40, “FRP
Reinforcement in RC Structures”, International Federation for Structural
Concrete, Lausanne, Switzerland, (2007),
160p. |
Available from: Int'l
Federation for Structural Concrete
fib.epfl.ch
Italian National Research Council
|
CNR-DT 203/2006,
"Guide for the Design and Construction of Concrete Structures Reinforced
with Fiber-Reinforced Polymer Bars", Italian National Research Council,
Rome, Italy, (2007), 35p. |
Available from:
Italian
National Research Council
www.cnr.it
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Concrete Protection
Products, Inc.
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Sales/Warehouse:
627-C Graves Street
Kernersville, NC 27284
Phone: 336-993-2461
Fax: 336-996-2732
Email:
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Mailing Address:
Concrete Protection Products, Inc.
P.O. Box 786
Oak Ridge, NC 27310
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