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Tensile strength and Mechanical Properties Of FIBER REINFORCED

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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
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
Fiberglass rebar negative
attributes
  Low Modulus of Elasticity
  Brittle nature
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
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
Experimental Program
 Setup:
  Cut specimen to
   appropriate length
  Affix strain gauges
   to bars
  Encase select
   samples in steel
   tubing
Experimental Program
 Testing Method
  Secure specimen in
   SATEC machine
  Connect wires to
   strain gauge boxes
  Apply load
  Collect data
Observations
  Slippage
  Epoxy failure
  Tensile performance
  Specimen failure
Experimental Results


                                                                       Modulus
                                                      Failure             of
                    diameter     area      failure     stress  Failure Elasticity
              Bar      (in)      (in2)  (force - kip)   (psi)   strain   (psi)
 steel ends   A           0.64   0.3217         29.70    92322 0.01968 4.00E+06
              B           0.64   0.3217         21.96    68263 0.01840 4.00E+06
 naked clamp C           0.41    0.1320         9.75       70374     0.02360 6.00E+07
             D           0.41    0.1320 -              -           -         -
Experimental Results



 Failure of naked bar
Graphical Results
                                                                                                                                                     stress-strain: bar-B
                                                 stress-strain: bar-A
                                                                                                                                                                                   y = 4E+06x + 143.31
                                                                                y = 4E+06x + 6742.8                           100000
                 105000                                                                                                                                                                 R2 = 0.9918
                                                                                     R2 = 0.9992
                                                                                                                              80000
                 85000
  stress (psi)




                                                                                                                                                                                     stress vs. strain (B)




                                                                                                               stress (psi)
                                                                                stress vs strain(A)                           60000
                 65000
                                                                                Linear (stress vs strain(A))                  40000
                                                                                                                                                                                     Linear (stress vs. strain
                 45000                                                                                                        20000                                                  (B))
                 25000                                                                                                            0
                          0   0.005      0.01      0.015      0.02   0.025                                                             0   0.005    0.01      0.015         0.02
                                                                                                                              -20000
                                              strain                                                                                               strain




                                                 stress-strain: bar-C
                                                                                 y = 6E+06x - 67613                             BAR A: large diameter steel ends
                                                                                     R2 = 0.9978
                 80000
                                                                                                                                BAR B: large diameter naked ends
                 60000                                                             stress vs. strain (C)
  stress (psi)




                 40000                                                                                                          BAR C: small diameter steel ends
                                                                                   Linear (stress vs. strain
                 20000                                                             (C))
                                                                                                                                BAR D: small diameter naked ends (results unattainable)
                     0
                      0.01            0.015            0.02             0.025
                                              strain
Conclusion
  Developed method relatively successful
  Modulus of Elasticity much less than steel
  Failure stress much greater than steel
Sources of Error
 Failure of epoxy to perform to full potential
 Specimen not completely vertical
 Slippage
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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