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Flexural Strengthening of Reinforced Concrete Beams by FRP Composites to Reduce Creep Deflection

Zarringol, Mohammad Reza | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 44366 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Kazemi, Mohammad Taqhi
  7. Abstract:
  8. The strengthening of reinforced concrete structures with externally bonded fibre reinforced polymer (FRP) laminates has shown excellent performance, so this technology is rapidly replacing externally bonded steel plates, steel or concrete jackets, and many traditional techniques available. In this study strengthening of reinforced concrete beams by GFRP to reduce creep deflection is investigated by mathematical method using available relations. Five RC beams with different dimensions, with and without strengthening with GFRP laminate, were investigated for their creep deflection. The creep coefficient of beams selected from experimental result that were mentioned in RILEM DATA BANK. In this study the effects of the following parameters are considered on the creep deflection of strengthened RC beams using GFRP laminate: different creep models, various concrete strength, age, time of application of GFRP laminate, steel ratio, GFRP ratio and type of FRP. Also the effects of following parameters are considered on failure modes of strengthened RC beams using GFRP laminate: Different steel ratio and GFRP ratio. For this aim the MATLAB program is used to formulate the calculation of the creep deflection using the effective modulus method (EMM) and analysis of ultimate limit state (ULS) in order to investigate the effects of GFRP laminate on a creep deflection and failure mode of the strengthened beams. Parametric study is conducted by using simplified relation ACI code and other approaches
  9. Keywords:
  10. Creep ; Fiber Reinforced Polymer (FRP) ; Failure Modes ; Reinforcement Concrete Beam ; Flexural Strength ; Carbon Fiber Reinforced Polymer (CFRP)

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  • Abstract
  • Acknowledgements
  • Introduction
    • General
    • Creep Effect on Strengthened RC Members
    • Objective and Scope of Study
    • Thesis Structure
  • Concrete, FRP and FRP Strengthened RC Beams
    • Introduction
    • Elastic Modulus of Concrete
      • Prediction equations recommended by ACI
      • CEB-FIP Model
      • Gardner model
    • Development of strength by time
    • Creep of Concrete
      • Definition of creep of concrete
      • Basic creep:
      • Drying creep:
      • Loading rate
    • Significance of creep
      • Factors influencing creep
    • Fiber Reinforced Polymer (FRP)
    • Mechanical properties of FRP
    • Application in Retrofitting
    • Failure modes of RC beams strengthened with FRP
      • Crushing of the concrete in compression before yielding of the reinforcing steel
      • Yielding of the reinforcing steel in tension followed by rupture of the FRP laminate
      • Yielding of the steel in tension followed by concrete crushing
      • Debonding of the FRP from the concrete substrate
    • Experimental Studies on Long-Term Behavior of FRP strengthened RC Beams
  • Creep prediction
    • General
    • ACI
    • CEB-FIP model
    • Bazant B3 model
    • Gardner-Lockman GL2000 model
    • Comparison with the available results
    • Time-Dependent Deflection
    • ACI 318 approach (ACI 318-2011)
    • Effective modulus method (ACI 209R-92)
    • Adjusted effective modulus method (ACI 209R-92)
    • Branson’s Approach (Branson 1977)
    • Mayer’s Approach (Mayer 1976)
    • Gilbert’s Approach (Gilbert 1999)
    • Comparison with experimental data
  • Time-Dependent Behavior of FRP Strengthened RC Beams
    • General
    • Short-Term Deflection
    • Time-Dependent Deflection
      • ACI Approach (ACI Committee 318-2011)
      • Effective Modulus Method
        • Adjusted effective modulus method
    • An example on deflection of a FRP strengthened RC beam under sustained loading by EMM method and ACI209
      • Initial deflection of un-strengthened RC beam:
      • Short term deflection of strengthened RC beam:
      • Creep deflection of un-strengthened RC beam (due to dead load plus 20%live load)
      • Creep deflection of strengthened beam with GFRP laminates:
  • Effect of GFRP on reduction of creep deflection
    • Introduction
    • Various parameters considered in this study
      • Effect of GFRP on reduction of creep deflection
      • Failure modes consideration
      • Calculation method
    • Material properties
      • Beam specimens
      • Concrete properties
      • FRP system properties:
    • Consideration of steel and GFRP ratio on failure modes
      • Failure modes of the beam specimens
      • Effect of steel ratio
      • Effect of GFRP ratio
    • Consideration of a different influencing parameters on a creep deflection
      • Prediction of creep deflection by various creep models
      • The effect of concrete strength
      • Effect of GFRP laminate on creep deflection, with different steel ratio
      • Effect of GFRP ratio on creep deflection
      • Effect of GFRP laminate on creep deflection by time
      • Effect of time of GFRP laminate application on creep deflection
      • Effect of type of FRP laminate on creep deflection
  • Conclusions and future study
    • Review of Work
    • Summary of Findings
    • Recommendations for Further Study
  • References
  • Mixture of concrete
  • Appendix B Matlab program
  • Appendix C RILEM data bank: Tables
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