TENSILE STRENGTH AND MECHANICAL PROPERTIES OF FIBER REINFORCED PLASTIC REINFORCING BARS

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TENSILE STRENGTH AND MECHANICAL PROPERTIES OF
FIBER REINFORCED PLASTIC REINFORCING BARS

• David Imam and Allison Johnson-Moore
• Undergraduate Civil Engineering Research
• University of Southern California 

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Fiberglass rebar positive attributes

• Impervious to chloride ion and chemical attack
• Tensile strength greater than steel
• 1/4th weight of steel reinforcement
• Transparent to magnetic fields and radio
  frequencies
• Electrically non-conductive
• Thermally non-conductive

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Fiberglass rebar negative attributes

• Low Modulus of Elasticity
• Brittle nature

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Objective

• This exploratory study was carried out to for
  two purposes
• to develop a suitable method for producing
  uniform stress throughout the member during
  testing
• to investigate the tensile strength of Fiber
  Reinforced Plastic (FRP) reinforcing bars

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Experimental Options

• Analyze a plain FRP specimen
• Wrap the ends of the sample in epoxy-coated
  carbon fiber cloth
• Encase the ends of the sample with metal sleeves

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Experimental Program

• Setup
• Cut specimen to appropriate length
• Affix strain gauges to bars
• Encase select samples in steel tubing

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Experimental Program

• Testing Method
• Secure specimen in SATEC machine
• Connect wires to strain gauge boxes
• Apply load
• Collect data

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Observations

• Slippage
• Epoxy failure
• Tensile performance
• Specimen failure

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Experimental Results
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Experimental Results

• Failure of naked bar

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Graphical Results
BAR A large diameter steel ends BAR B large
diameter naked ends BAR C small diameter steel
ends BAR D small diameter naked ends (results
unattainable)
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Conclusion

• Developed method relatively successful
• Modulus of Elasticity much less than steel
• Failure stress much greater than steel

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Sources of Error

• Failure of epoxy to perform to full potential
• Specimen not completely vertical
• Slippage

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Conclusion

• Improvements for Testing/Producing FRP
• Use a more ductile polymer
• Allow Epoxy to fully set
• Custom design metal sleeves
• Experiment with a variety of wrapping procedures

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