Repair and Retrofit on Beam and Column Joints


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A research experiment has been conducted on the structural performance of repaired minor damaged reinforced concrete beam and column Joints using composite known as CFRP (Carbon Fiber Reinforced Polymer) under simulated cyclic 2D loadings to find the practical lamination repair scheme for flexural strengthening, shear strengthening, and joint strengthening.

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  • Fiber reinforced polymer (or FRP) materials are created by combining high strength, thread-likefibers with a polymer or resin material. The result is a rigid material that is high strength yet light weight. The fibers in the materialgive the material all of its strength and stiffness characteristics while the polymer holds thefibers in alignment.
  • Repair and Retrofit on Beam and Column Joints

    1. 1. Repair and Retrofit Systems for Reinforced Concrete Beam-Column Joints using Carbon Fiber Reinforced Polymer (CFRP) subjected to cyclic/seismic loadings – Research in progress<br />
    2. 2. Student Researchers: <br />AmeraldSimanungkalit (Presenter)<br /> Brendon Baich<br />Tuan Quoc Le<br />Faculty Advisors: <br />Dr. Uksun Kim<br />Dr. PinakiChakrabarti<br />Dr. David Naish <br />Lab Technicians:<br />Leroy Sanchez (Civil Engineering Dept.)<br />John (Mechanical Engineering Dept.) <br />
    3. 3. Acknowledgements(Funding) <br />
    4. 4. Two recent enormous California earthquakes :<br />Loma Prieta (1989)<br /> and <br /> Northridge (1994)<br />
    5. 5. Loma Prieta earthquake<br />October 17, 1989<br />a magnitude earthquake measured 6.9 <br />that caused 63 deaths, injured 3,757 people a<br />8,000 to 12,000 people homeless.<br /> The aftermath of the earthquake totaled approximately 6 to 13 billion dollars in damages. <br />
    6. 6. Loma Prieta Earthquake<br />RESIDENTIALS<br />FREEWAYS<br />BRIDGES<br />PARKING STRUCTURE<br />
    7. 7. Northridge earthquake<br />January 17, 1994 <br />with a magnitude earthquake measured 6.9<br />that caused 72 deaths, over 9,000 injuries <br />The aftermath of the earthquake totaled approximately $20 billion in damages. <br />
    8. 8. Northridge Earthquake<br />PARKING STRUCTURE<br />BRIDGES<br />HOSPITALS<br />APARTMENTS<br />
    9. 9. Unfortunately,<br /> “ California has a 99.7% chance of having a magnitude 6.7 or larger earthquake during the next 30 years. The likelihood of a more powerful quake of magnitude 7.5 or greater in the next 30 years is 46%”<br />Southern California Earthquake Center (SCEC) <br />& U.S Geological Survey (USGS)<br />
    10. 10. Civil Engineers Duty<br />Provide Solutions :<br />1. Safety<br />2. Practical<br />3. Cost Efficient<br />4. List goes on….<br />
    11. 11. Structural Element: Joint Failures<br />Focal point of research since 1994 Northridge EQ in structural engineering community<br />
    12. 12. Vcol<br />C2 = Ts2<br />Vb2<br />Vb1<br />C1 = Ts2<br />Vcol<br />(b) internal stress resultants acting on joint<br />Joint Mechanism<br />(a) moments, shears, axial loads acting on joint<br />
    13. 13. Repair and Retrofit Solutions<br />Bonded steel plates<br />Steel or concrete jackets <br />External post-tensioning to the structural elements<br />AFTER<br />BEFORE<br />
    14. 14. Repair & Retrofit using CFRP<br />Pros <br />Highest strength, <br />Highest stiffness, <br />Most durable fibers. <br />Highly resistant to most environmental conditions.<br />Low creep<br />High fatigue endurance. <br />Cons<br /><ul><li>fabricate this composite material is very expensive compared to traditional concrete and steel materials.
    15. 15. Required Chemicals (epoxy, resin, etc)</li></ul> the cost of the material is balanced by much lower installation costs. <br />
    16. 16. CFRP (Carbon Fiber Reinforced Polymer)<br />
    17. 17. CFRP Property& Manufacture<br />
    18. 18. Previous research done at CSUF<br />1998<br />Dr. Chakrabarti<br />2009<br />“Study of Concrete Beam Column Joint Repair with Carbon Fiber Reinforced Polymer” (2009) By Delgado, H, and Lam, C.<br />
    19. 19. Improvement from previous<br />Fully externally wrap CFRP<br /> (not practical)<br />Excess materials or layers of lamination<br /> (not economical)<br />
    20. 20. Improvement from previous<br />Precise Data (Test set-up improvement)<br /> Shifting (Moving)<br />Additional prestressing wires on beams (Specimen 3&4)<br />
    21. 21. Construction of Specimens – Rebar and Formworks<br />STEEL CAGES<br />FORMWORKS<br />GRINDING REBARS FOR STRAIN GAGES<br />INSPECTIONS<br />
    22. 22. Construction of Specimens – Concrete Pouring<br />SLUMP TEST<br />FORMWORKS LAYOUT<br />CYLINDER AND BEAM TESTS<br />28 DAYS – CONCRETE CURING<br />
    23. 23. Material Testing<br />PRESTRESSING WIRES<br />HYDRAULIC JACKS<br />LOAD TEST<br />COMPRESSION TEST<br />UNIVERSAL<br />TESTING<br />MACHINE (UTM)<br />ACI 318-08<br />ACI 440.2R-08<br />FLEXURE TEST<br />
    24. 24. Typical Specimen Details<br />STRAIN GAGES<br />
    25. 25. Typical Specimen Section Details<br />4<br />
    26. 26. Experiment Test Set-up<br />
    27. 27. Test on Specimen#1 (RCBC-1)<br />
    28. 28. Cracking Behavior<br />SHEAR CRACKS<br />
    29. 29. Result Data<br />Load vs Deflection - No Shifting<br />Not symmetrical<br />
    30. 30. CFRP Proposal Scheme<br />
    31. 31. 3D Rendering<br />
    32. 32. Apply CFRP Increased Load<br />
    33. 33. Research Expectations<br />After comparing the controlled and repair specimens:<br />Accurate result data<br />Better performance (higher Loadings)<br />Practical CFRP repair scheme<br />Providing less layers CFRP and resin materials<br />Providing new standard set-up for the next research <br /> (post tension beam) <br />
    34. 34. Thank You<br />Amerald Simanungkalit, EIT, S.M. ASCE.<br /><br />Questions?<br />BEAM TO COLUMN JOINTS<br />