Performance of Steel Fiber under Fire and Impact Loading (Piti Sukontasukkul)

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Performance of Steel Fiber under Fire and Impact Loading (Piti Sukontasukkul)

  1. 1. Performance of Steel Fiber Reinforced Concrete under High Temperature and Impact Load from Direct Fire Weapon Assc. Prof. Dr. Piti Sukontasukkul King Mongkut University of Technology-North Bangkok Thailand Concrete Association
  2. 2. Presentation Topic Performance of SFRC subjected to high temperature • Concrete under high temperature • SFRC under high temperature • Steel fiber vs. Other fibers Performance of SFRC under impact loading • Structure under attack • Material behavior under impact loading • Performance of SFRC under impact loading
  3. 3. Performance of SFRC under High Temperature
  4. 4. General Knowledge To Stop Fire Credit http://en.wikipedia.org/wiki/Fire • Turning off the gas supply, which removes the fuel source; • Covering the flame completely, which remove the oxygen in the air and displaces it CO2; • Application of water, which removes heat from the fire faster than the fire can produce it • Application of a retardant chemical such as Halon to the flame, which retards the chemical reaction itself until the rate of combustion is too slow to maintain the chain reaction.
  5. 5. Temperature by Flame Appearance Temperatures of flames by appearance Red Orange White Just visible: 525 °C (980 °F) Deep: 1,100 °C (2,000 °F) Whitish: 1,300 °C (2,400 °F) Dull: 700 °C (1,300 °F) Clear: 1,200 °C (2,200 °F) Bright: 1,400 °C (2,600 °F) Cherry, dull: 800 °C (1,500 °F) Cherry, full: 900 °C (1,700 °F) Credit http://en.wikipedia.org/wiki/Fire Cherry, clear: 1,000 °C (1,800 °F) Dazzling: 1,500 °C (2,700 °F)
  6. 6. Behavior of Concrete Subjected to High Temperature Pore pressure rises Increasing compression stress at the heated surfaces Internal cracking between agg. and paste Cracking and spalling between paste and rebar. Strength drop ?????
  7. 7. Expansion under Thermal Difference Expansion of RC. Structure under High Temp. include Expansion of aggregates Expansion of cement paste Expansion of rebar Thermal Expansion Coefficient Cement paste 11-16 x 10-6 /oC Coarse aggregate 0.9-12 x 10-6/oC Steel 11-12 x 10-6 /oC
  8. 8. Temperature Change vs. Strain
  9. 9. Type of Thermal Cracking and Spalling Violent Spalling, Progressive Gradual Spalling, • Appear at the very beginning of the exposure. • A separation of small pieces from the cross section, during energy release. They form popping off pieces with a certain speed, and a cracking sound. • After long period of exposure, loss of strength due to internal crack and deterioration of cement paste cause this kind of spalling. Corner Spalling Explosive Spalling, • The type of spalling that occurs when a corner of concrete breaks off due to the restrained expansion or the difference in TEC of paste and rebar. • This occurs when there is a thermal gradients in the cross-section (one side of structure expose to high temperature while the other side does not).
  10. 10. http://www.promat-tunnel.com/en/concretespalling-effect-standard-fire-tests.aspx
  11. 11. Plain Concrete vs. SFRC subjected to Fire Plain Concrete SFRC • Unequal expansions of cement paste and aggregates cause cracking and spalling to occur. • At temperature lower 200oC, the expansions are still small, in many cases the strength is found to remain unchanged or may be increased slightly. • At temperature higher than 200oC, the strength begins to drop. • The cracks are restrained by fibers, this reduce the process of disintegration and maintain the ability of concrete to sustain load. • Similar results are found at temperature lower than 200oC, increasing in strength and toughness is found. • At temperature higher than 200oC, both strength and toughness are found to decrease but still higher than plain concrete
  12. 12. Compressive Strength Mahasneh, B, The Effect of Addition of Fiber Reinforcement on Fire Resistant Composite Concrete Material, J. Applied Sci., 5 (2): 373-379, 2005
  13. 13. Tensile Strength Mahasneh, B, The Effect of Addition of Fiber Reinforcement on Fire Resistant Composite Concrete Material, J. Applied Sci., 5 (2): 373-379, 2005
  14. 14. EXPERIMENTS AT KMUTNB:FLEXURAL PERFORMANCE OF FRC SUBJECTED TO FIRE
  15. 15. Flexural Toughness ASTM C1018 Flexural Toughness FIRST CRACK •  = Area under the curve up to elastic limit (OAB) 10.5δ 5.5δ 3δ δ 0 0' • 10.5 = Area under the curve up to 10.5 times of  (OAGH) = Area OACD / Area OAB • I10 = Area OAEF / Area OAB • I20 = Area OAGH / Area OAB B D F H DEFLECTION FIRST CRACK A C E G LOAD • I5 E G • 5.5 = Area under the curve up to 5.5 times of  (OAEF) Toughness Indexes C LOAD • 3 = Area under the curve up to 3 time of  (OACD) A 10.5δ 5.5δ 3δ δ 0 0' B DEFLECTION D F H
  16. 16. Standard Fire Test ASTM E119-98 Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974.
  17. 17. Flexural Response of PC vs. SFRC 30 0.5%SFRC 30 25 Load (kN) Plain Concrete 25 Load (kN) 20 Room Temp 15 15 5 600oC 5 600oC 10 400oC 10 400oC 20 800oC 0 800oC 0 2 0 0 0.2 0.4 0.6 Deflection (mm) 0.8 Room Temp 4 Deflection (mm) 6 8 1 30 400oC 1.0%SFRC 25 SFRC (@Bekeart HE Steel Fiber) Load (kN) Plain Concrete 600oC 20 15 Room Temp 10 800oC 5 Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974. 0 0 2 4 Deflection (mm) 6 8
  18. 18. Toughness Indexes of SFRC SFRC 25.0 20.0 15.0 Before subjecting to Fire 10.0 5.0 0.5% 1.0% Room Temp 0.5% 1.0% 0.5% 400 C I5 1.0% 600 C I10 0.5% 1.0% 800 C I20 Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974. After subjecting to Fire (800oC)
  19. 19. Steel Fiber vs. Synthetic Fibers 30 30 0.5%PE/PP FRC 0.5%PPFRC 25 25 20 400oC Room Temp 15 10 Load (kN) Load (kN) 20 600oC 15 600oC 10 800oC 5 400oC 5 800oC 0 0 2 4 Deflection (mm) 6 8 0 PP/PE Fiber (@Strux Fiber) 2 4 Deflection (mm) 6 8 PPRC (@Bekeart PP Fiber) 30 30 1.0%PE/PP FRC 1.0%PPFRC 25 25 400oC 400oC 20 15 Load (kN) 20 Load (kN) Room Temp 0 600oC 600oC 15 10 10 5 5 800oC Room Temp 0 800oC Room Temp 0 0 2 4 Deflection (mm) 6 8 0 2 4 Deflection (mm) 6 8
  20. 20. Flexural Toughness Synthetic Fibers PEFRC PPFRC 25.0 30.0 20.0 25.0 20.0 15.0 15.0 10.0 10.0 5.0 5.0 - 0.5% 1.0% Room Temp 0.5% 1.0% 0.5% 400 C I5 1.0% 0.5% 600 C I10 I20 Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974. 1.0% 800 C 0.5% 1.0% Room Temp 0.5% 1.0% 0.5% 400 C I5 1.0% 600 C I10 I20 0.5% 1.0% 800 C
  21. 21. Cross-section after 800oC Synthetic FRC Steel FRC Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974.
  22. 22. Ultrasound Test Pulse Velocity (m/s) 5,000 4,500 4,000 3,500 3,000 2,500 Plain PEFRC-0.5 PEFRC-1.0 PPFRC-0.5 PPFRC-1.0 SFRC-0.5 SFRC-1.0 Room 400 C 600 C 800 C 4,795 4,683 4,718 4,667 4,728 4,683 4,667 4,445 4,383 4,295 4,357 4,122 4,525 4,277 4,132 4,260 3,590 3,702 3,620 3,815 3,687 3,257 2,922 2,866 2,883 2,808 2,990 2,972 Sukontasukkul, P., and Pomchiengpin, W., Post-Crack (or Post Peak) Flexural Reponse and Toughness of FRC after Exposure to Elavated Temperature, Journal of Construction and Building Material (JCBM), Vol. 24, 2010, pp. 1967-1974.
  23. 23. Conclusion Steel fibers exhibit the ability to improve the fire resistance of concrete as seen by the ability the maintain strength and toughness after subjection to high elevated temperature. Steel fiber’s ability to bridge across the cracks that occurred during exposure to fire play an important role on this matter.
  24. 24. Concrete Under High Rate of Loading Concrete may sometime be required to withstand dynamic loads due to impact, or explosion. Under high rate of loading, the strength of concrete increases with the increasing loading rate. 90 Static loading Impact loading (250mm) Impact loading (500mm) 80 70 Large cracks are typically found. Stress (MPa) Cracks are forced to propagate through aggregates. 60 50 40 30 20 10 - 0.005 0.010 0.015 Strain 0.020 0.025 0.030
  25. 25. SFRC under Impact Loading Mechanical Properties: strength increases, toughness increases and bond strength increases Multiple cracks with less severity are often found. 90 Static loading Impact loading (250mm) Impact loading (500mm) 80 70 60 Stress (MPa) Under high rate of loading, fibers are forced to pullout at faster rate, thus cause the increase in mechanical properties. 50 40 30 20 10 - 0.005 0.010 0.015 Strain 0.020 0.025 0.030
  26. 26. Structures Being Hit by Bullets Three Scenarios • Penetrated Bullets: When the bullets hit the wall and penetrate through. They injure people or damage properties • Un-penetrated Bullets: when the bullets hit the wall, but do not penetrate, instead turning into flying debris (broken concrete pieces and ricocheted bullets). The debris injure people and damage properties. • Panicking: People get panic, running around, stumbling and get hurt.
  27. 27. Typical Failure Patterns of Bulletproof Panel Global Local Penetration Perforation Flexure Scabbing Spalling In the case of impact loading by bullet which leading to penetration, the specimen response is usually dominated by the local response of the small zone at the contact area
  28. 28. Main Ideas of Bulletproof Panel Requirement for bulletproof panel: • Penetration or perforation must not occurs. In order to achieve that: • Improve impact resistance by increasing strength and energy absorption ability of the panel. • Anticipating energy dissipation by using soft medium into the panel. http://www.examiner.com/article/ethicspanel-ruling-keeps-jobsohio-bullet-proofon-kasich-board-biz-deals
  29. 29. Two Types of Panel SFRC Panel Rubberized Concrete Steel Fiber Reinforced Concrete • Fiber: Hooked End steel fiber (©Dramix Bekeart), Addition rate: 2%-4% • Thickness: 3 cm. • Category: Improve impact resistance using steel fiber. Double layer: SFRC and Rubberized Concrete • Fiber: Hooked End steel fiber (©Dramix Bekeart) , Addition rate: 2%-4% • Crumb rubber: Commercial type, Size: passing seive No. 6. • Panel Thickness: 3 cm. Varied Thickness between layer from 0.5:2.5, 1.0:2.0 and 1.5:1.5 • Category: • Adding energy dissipation medium (rubberized concrete), • Increase impact resistance using steel fiber T1 T2
  30. 30. Two Types of Bullet Manufacturer Winchester Load FMJ Mass Velocity 7.5 g (115 gr) 352 m/s Energy 462 J Remington FMJ 15 g (230 gr) 255 m/s 483 J Expansion Penetration 9.1 mm 620 mm 11 mm 690 mm PC 41 mL TSC 174 mL 70.3 mL 150 mL
  31. 31. Failure Patterns PC vs. SFRC Panel Plain concrete Panel 29 Front 43 . Back SFRC Panel .
  32. 32. Failure Patterns : Double Layer Panel Typical Failure Patterns Partially Energy Dissipation Ideal Failure Patterns Full Energy Dissipation
  33. 33. Passing Requirement Type R25 R50 R75 S2 S3 S4 R50/S2 R75/S2 R100/S2 R50/S3 R75/S3 R100/S3 R50/S4 R75/S4 R100/S4 A-R75/S2 B-R75/S2 A-R75/S3 B-R75/S3 9 mm Failure Type Perforation Perforation Perforation Scabbing Scabbing Scabbing Scabbing Scabbing + Spalling Scabbing + Spalling Scabbing Scabbing Scabbing + Spalling Scabbing + Spalling Scabbing Scabbing Scabbing + Spalling Scabbing + Spalling Scabbing + Perforation Scabbing + Perforation 11 mm Classification Failure Type not pass Perforation not pass Perforation not pass Perforation pass Scabbing pass Scabbing pass Scabbing pass Scabbing pass Scabbing + Spalling pass Scabbing + Spalling pass Scabbing pass Scabbing pass Scabbing pass Scabbing pass Scabbing pass Scabbing pass Scabbing + Perforation pass Scabbing + Perforation not pass Scabbing + Perforation not pass Scabbing + Perforation Classification not pass not pass not pass pass pass pass pass pass pass pass pass pass pass pass pass not pass not pass not pass not pass
  34. 34. Typical Acceleration Res. SFRC (9 mm)
  35. 35. Typical Acceleration Res. Double Layer (9 mm Bul.)
  36. 36. Comparison Single Layer Plate Double Layer Plate Responding time: Slower in Double layer plate Acceleration Value: Lower in Double layer plate
  37. 37. Center Acc. vs. Rubber content Double-layer plate 1,200.00 0% Crumb Rubber 50% CR (0.5/2.5) 75%CR (0.5/2.5) 100%CR (0.5/2.5) 1,053.38 1,000.00 Acceleration (m2/s) 864.41 819.33 800.00 735.98 785.21 759.05 602.97 600.00 432.51 400.00 579.81 526.22 389.40 353.43 200.00 SFRC2% SFRC3% SFRC4%
  38. 38. 200.00 100.00 - 432.51 355.28 300.00 100R4S (0.5/2.5) 735.98 648.22 546.52 353.43 100R3S (0.5/2.5) 100R2S (0.5/2.5) 602.97 506.47 389.40 452.31 400.00 75R4S (0.5/2.5) 75R3S (0.5/2.5) 738.45 864.41 759.05 1,000.00 75R2S (0.5/2.5) 526.22 451.34 500.00 50R4S (0.5/2.5) 554.84 600.00 50R3S (0.5/2.5) 700.00 628.42 800.00 819.33 900.00 50R2S (0.5/2.5) Acceleration (m2/s) Bullet Type vs. Center Acceleration 9 mm. 11 mm.
  39. 39. Displacement (9 mm.) SFRC 2% 50RS2 SFRC 3% 50RS3
  40. 40. Conclusions Steel fiber reinforced concrete exhibit superior impact resistance as seen by the test results that no perforation occur in the SFRC panels. Crumb rubber used in this study has shown it ability to enhance the efficiency of the bulletproof SFRC panels. The results are successfully shown that the rubberized concrete layer is able to act as a cushion layer and dissipate the impact energy from the bullet test as seen by the decreasing values of acceleration, displacement and D/W ratios.

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