The document discusses ongoing research on repairing and retrofitting beam-column joints in reinforced concrete using carbon fiber reinforced polymer (CFRP) to withstand seismic loads, particularly in light of past California earthquakes that caused significant damage. It highlights the strengths and weaknesses of CFRP materials and outlines methodologies for improving repair techniques based on previous studies. The researchers aim to enhance performance data and establish a new standard for using CFRP in structural engineering applications.

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

2. Student Researchers: AmeraldSimanungkalit (Presenter) Brendon BaichTuan Quoc LeFaculty Advisors: Dr. Uksun KimDr. PinakiChakrabartiDr. David Naish Lab Technicians:Leroy Sanchez (Civil Engineering Dept.)John (Mechanical Engineering Dept.)

3. Acknowledgements(Funding)

4. Two recent enormous California earthquakes :Loma Prieta (1989) and Northridge (1994)

5. Loma Prieta earthquakeOctober 17, 1989a magnitude earthquake measured 6.9 that caused 63 deaths, injured 3,757 people a8,000 to 12,000 people homeless. The aftermath of the earthquake totaled approximately 6 to 13 billion dollars in damages.

6. Loma Prieta EarthquakeRESIDENTIALSFREEWAYSBRIDGESPARKING STRUCTURE

7. Northridge earthquakeJanuary 17, 1994 with a magnitude earthquake measured 6.9that caused 72 deaths, over 9,000 injuries The aftermath of the earthquake totaled approximately $20 billion in damages.

8. Northridge EarthquakePARKING STRUCTUREBRIDGESHOSPITALSAPARTMENTS

9. Unfortunately, “ 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%”Southern California Earthquake Center (SCEC) & U.S Geological Survey (USGS)

10. Civil Engineers DutyProvide Solutions :1. Safety2. Practical3. Cost Efficient4. List goes on….

11. Structural Element: Joint FailuresFocal point of research since 1994 Northridge EQ in structural engineering community

12. VcolC2 = Ts2Vb2Vb1C1 = Ts2Vcol(b) internal stress resultants acting on jointJoint Mechanism(a) moments, shears, axial loads acting on joint

13. Repair and Retrofit SolutionsBonded steel platesSteel or concrete jackets External post-tensioning to the structural elementsAFTERBEFORE

14. Repair & Retrofit using CFRPPros Highest strength, Highest stiffness, Most durable fibers. Highly resistant to most environmental conditions.Low creepHigh fatigue endurance. Consfabricate this composite material is very expensive compared to traditional concrete and steel materials.

15. Required Chemicals (epoxy, resin, etc) the cost of the material is balanced by much lower installation costs.

16. CFRP (Carbon Fiber Reinforced Polymer)

17. CFRP Property& Manufacture

18. Previous research done at CSUF1998Dr. Chakrabarti2009“Study of Concrete Beam Column Joint Repair with Carbon Fiber Reinforced Polymer” (2009) By Delgado, H, and Lam, C.

19. Improvement from previousFully externally wrap CFRP (not practical)Excess materials or layers of lamination (not economical)

20. Improvement from previousPrecise Data (Test set-up improvement) Shifting (Moving)Additional prestressing wires on beams (Specimen 3&4)

21. Construction of Specimens – Rebar and FormworksSTEEL CAGESFORMWORKSGRINDING REBARS FOR STRAIN GAGESINSPECTIONS

22. Construction of Specimens – Concrete PouringSLUMP TESTFORMWORKS LAYOUTCYLINDER AND BEAM TESTS28 DAYS – CONCRETE CURING

23. Material TestingPRESTRESSING WIRESHYDRAULIC JACKSLOAD TESTCOMPRESSION TESTUNIVERSALTESTINGMACHINE (UTM)ACI 318-08ACI 440.2R-08FLEXURE TEST

24. Typical Specimen DetailsSTRAIN GAGES

25. Typical Specimen Section Details4

26. Experiment Test Set-up

27. Test on Specimen#1 (RCBC-1)

28. Cracking BehaviorSHEAR CRACKS

29. Result DataLoad vs Deflection - No ShiftingNot symmetrical

30. CFRP Proposal Scheme

31. 3D Rendering

32. Apply CFRP Increased Load

33. Research ExpectationsAfter comparing the controlled and repair specimens:Accurate result dataBetter performance (higher Loadings)Practical CFRP repair schemeProviding less layers CFRP and resin materialsProviding new standard set-up for the next research (post tension beam)

34. Thank YouAmerald Simanungkalit, EIT, S.M. ASCE.Amerald24@CSU.Fullerton.eduQuestions?BEAM TO COLUMN JOINTS