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New
Infrastructure Repair Method - Fiber Reinforced Plastics
The Need
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As the United States infrastructure gets
older, the need for repair and rehabilitation increases. Most of the constructed
facilities are deteriorating at a rate faster than they can be repaired. Nearly half of
the nation's 575,600 highway bridges are structurally deficient or functionally obsolete
(Engr. News Record, 11 Sept, 1995). Several studies have documented the three trillion
dollar rehabilitation /retrofitting need of U.S. infrastructure. Through the development
and use of composite materials, this tremendous problem could be solved. New materials
need to be developed that can act as a permanent "Band-Aid" that would not
require large amounts of demolition work to be done before repair begins. Also, simple
retrofits to reinforce substandard structures have a huge potential place in the
marketplace. |
Beam strengthened with Fiber Reinforced Plastic
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The Technology
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Thermal setting resins and fiber rods and
sheets are being used to repair and upgrade structural systems. High-strength FRP fabric
can be wrapped with relative ease around a bridge pier, a concrete column, or a concrete
beams. They are primarily used to stiffen columns and beams and to repair deteriorated
concrete components. |
The Benefits
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Tests have established that wrapped structural
elements, with confined concrete, can have an increase in strength and stiffness of 50% to
500% above that found with unwrapped elements. In addition, weak links in a structural
system such as the lap-splice area near the column-footing interface can be strengthened
to resist earthquake forces. Moreover, FRP plates and sheets are easier to install because
they only need to be glued to the surface of a structure, which requires less on-site
effort compared to steel plates. |
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Status
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Research and development (R&D) concerning
the strengthening and stiffening of reinforced concrete structural elements has been going
on in Europe, Japan, and North America for nearly ten years. Much of the surface repair
technology for defective bridge columns, smoke stacks and earthquake damaged buildings
originated in Japan and consisted of either wrapping preformed composite sheets around
structurally damaged column surfaces or jacketing smoke stacks with large-scale,
on-location filament winding.
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For example, the Constructed Facilities Center
at West Virginia University has been working closely with several U.S. and Japanese
industries to understand the behavior of concrete beams wrapped with CFRP fabrics through
extensive testing. Two Japanese companies have promoted their products to the construction
industry. One is the FITS method by Mistui Construction Co., which can improve existing RC
columns' shearing strength and deformation properties by wrapping the surface of the
columns with adhesive UD tape made of aramid fiber. The other is FTS system by Tonen
Corporation, which is dry type sheet material alighted carbon or glass fiber
unidirectionally on a thin back net with a layer of epoxy resin adhesive. Similarly in
California, concrete bridge columns have been retrofitted to enhance their flexural and
shear strength. For over ten years, Swiss Federal Laboratories for Material Testing and
Research has been investigating static and fatigue resistance of CFRP sheets that
reinforce concrete rectangular and T-beams on their tension side. FYFE Co. LLC is one of the companies which offer a wide range of FRP product
for use in various structural application, such as column, beam, slabs, wood piles, pipes,
masonry walls and tanks. |
Barriers
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One barrier to the widespread use of these
technologies using FRP materials for infrastructure repair is that they have not been
broadly accepted by any building codes. Some concerns still remain about FRP's fire
resistance, long-term creep characteristics, and aging due to ultraviolet rays or
degradation of bond forces with time. Also, a full understanding of failure behavior and
design models that would reflect the improvements in strength and stiffness of
rehabilitated or retrofitted concrete structural members still need to be developed. |
Points of Contact
- Professor Antonio Nanni, Civil Engineering
Department, University of Missouri-Rolla, 119 Butler-Carlton Civil Engineering Hall,
Rolla, MO 65409-0030. Phone: (573)341-4400. e mail: nanni@umr.edu.
- Dr. A. Zureick, 790 Atlantic Drive, Georgia
Institute of Technology, Atlanta, Georgia 30332-0355 USA, Phone: (404)894-2294, Fax:
(404)894-2278 email: abdul.zureick@ce.gatech.edu.
- Duane J Gee, FYFE Co. LLC, 6044 Cornerstone
Court W., Suite C San Diego, CA, 92121-4730, email: duane@fyfe.com
References
- Faza, S.S. and Gangarao, H.V.S. "Fiber
Composite Wrap for Rehabilitation of Concrete Structures", Infrastructures: New
Materials Engineering Conference; San Diego, CA, USA; 1994.
- Faza, S.S. and Gangarao, H.V.S.
"Experimental and Theoretical Behavior of Hybrid Concrete-Carbon Rectangular
Beams,", CFC Report to Tonen Corporation, 1994.
- FYFE Co. LLC home page, http://www.fyfe.com
- McConnell, V.P. "Bridge Column Retrofit
- Hybrid Woven Unifabric,", High Performance Composites, September/October 1993.
- Meier, U. and Deuring, M. "The
Application of Fiber Composites in Bridge Repair," Strasse and Verkehr, No. 9, 2p
1991.
- Tonen Corporation, Technical Brochure,
Tokyo, Japan, 1993.
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
SSL03/CHC
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