Steel fiber reinforced concrete

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Steel fiber reinforced concrete

  1. Advanced Concrete design (CE-6111) Prepared by Submitted to Md. Ahsan Habib Dr. Sharmin Reza Roll No: 1013110001 Assoc. Professor Dept. of Civil Engineering, MIST
  2. 2. INTERNATIONAL JOURNAL OF RESEARCH IN ENGINEERING AND TECHNOLOGY EISSN: 2319-1163 | PISSN: 2321-7308 PRESENTATION ON Steel fiber reinforced concrete and its use in building Author: Prakash Mondal 1 , Dilip Kumar Singha Roy 2 1 Assistant professor, Department of Civil Engineering, Dr. B.C.Roy Engineering College,Durgapur, WestBengal, India 2 Professor, Department of Civil Engineering, National Institute of Technology Durgapur, WestBengal, India
  3. 3. INTRODUCTION During the past 30 years, attempts have been made to enhance strength of reinforced concrete beams by bonding steel fibers to beam in terms of flexural or shear strength. The concrete construction field has shown a growing interest in the advantages of introduction of fiber reinforcement in structural elements. Among the different fibers available, e.g. steel, synthetic, glass, and natural fibers, the steel fiber is probably the most investigated and most commonly used. Fiber reinforcement today is mainly used in many applications such as industrial beam & floors, overlays, although other application areas exist. Some of the potential benefits of fibers in concrete are improved crack control and more strength than plain concrete,

 

 

  1. 4. FIBRE REINFORCED CONCRETE 4
  2. 5. FIBRE REINFORCED CONCRETE 5
  3. 6. SOME PICTURES OF STEEL FIBERS FIBRE REINFORCED CONCRETE 6
  4. 7. OBJECTIVE : 1. The main objective is to study the behavior of reinforced concrete beams strengthened with steel fiber. 2. To study the effect of steel fiber strengthening of RC Beams on ultimate load carrying capacity and failure pattern. 3. Comparative study of the crack pattern and crushing behavior between controlled beam and strengthened FRC beams.
  5. 8. Twelve reinforced concrete beams were cast and tested under two point loading, using fiber at three deferent depths for nine beams and three control beams. All The investigated beams have been divided into four sets with and without the use of fiber different depth of the beam. Fig-1: Longitudinal and Cross sections details of RC beams EXPERIMENTAL PROGRAMME
  6. 9. Serial no. Beam designation Beam Width (mm) Depth of Beam(mm) am(mm) Length of beam(mm) Use of Fiber SL1 P/B-1 150 200 1450 NO SL2 P/B-2 150 200 1450 NO SL2 P/B-3 150 200 1450 NO Table-1: Details of Reinforced Concrete Beam Fig-.2: Details of Reinforced Concrete Beam EXPERIMENTAL PROGRAMME (cont..)
  7. 10. Serial no. Beam designation Beam Width (mm) Depth of Beam(mm) Length of beam(mm) Use of Fiber SL4 F/B-1 150 200 1450 Full Depth of Beam SL5 F/B-2 150 200 1450 Full Depth of Beam SL6 F/B-3 150 200 1450 Full Depth of Beam Table-2: Details of Fully Fiber Reinforced Concrete Beam Fig.-3: Fiber Reinforced Concrete Beam EXPERIMENTAL PROGRAMME (cont..)
  8. 11. Serial no. Beam designation Beam Width (mm) Depth of Beam(mm) Length of beam(mm) Use of Fiber SL7 0.5D-B-1 150 200 1450 0.5d Depth of Beam SL8 0.5D-B-1 150 200 1450 0.5d Depth of Beam SL9 0.5D-B-1 150 200 1450 0.5d Depth of Beam Table-3: Details of 0.5 Depth Level of Fiber Reinforced Concrete Beams Fig.-4: Reinforced Concrete Beam with 0.5Depth Level of Fiber EXPERIMENTAL PROGRAMME (cont..)
  9. 12. Serial no. Beam designation Beam Width (mm) Depth of Beam(mm) Length of beam(mm) Use of Fiber SL10 TL.SB(F)-B-1 150 200 1450 Top Level of Tensile Steel Bar SL11 TL.SB(F)-B-1 150 200 1450 Top Level of Tensile Steel Bar SL12 TL.SB(F)-B-1 150 200 1450 Top Level of Tensile Steel Bar Table-4: Tensile bar depth Level of Fiber Reinforced Concrete Beams Fig.-5: Reinforced Concrete Beam (Fiber reinforced up to top level of tensile reinforced zone) EXPERIMENTAL PROGRAMME (cont..)
  10. 13. Steel Fiber: The steel fibers used in the present study were round and straight fibers. The diameter and length of the fibers were df=0.7 mm and lf=28 mm, respectively, The volume of steel fiber has been used in the concrete mixes is 1% of the total volume of the demarcated concrete throughout the investigation. TEST MATERIAL
  11. 14. The high strength concrete mix design was done using IS: 10262–2009. By conducting trial mixes and making suitable adjustments in the mix proportion, the following mix proportion has finally been arrived at as shown in Table-8. Content Water Cement F.A. C.A. (kg) 197 394 641.93 1236.67 Ratio 0.5 1.0 1.629 3.13 Table-8: Mix Proportion of Concrete Mix Design
  12. 15. Test Procedure: The beams were tested under two point loading on 1000 kN loading frame. The test specimen was simply supported on rigid supports. Two point loads were applied through a rigid spread beam. The specimen was loaded using a 1000 kN jack. The loading were performed through displacement control with a rate of 0.04 mm/sec. A linear voltage differential transducer (LVDT) was used to measure the vertical deflection at mid-span and under the load points. At the end of every 20 kN load increment, observations and measurements were recorded for the crack development and propagation on the beam surfaces. The load at which the diagonal crack and the ultimate shear crack developed was also recorded. Crack patterns were marked on the beams. The test set-up is presented in Fig.7. BEAM DETAILS AND TESTING
  13. 16. Fig.-7: Beam and LVDT arrangement in 1000 kN Loading Frame
  14. 17. Ultimate Load and Modes of Failure: It was observed from Fig.8 for the Reinforced Concrete Beam (i.e. control beams) that in the region of the mid span, flexure-shear cracks were initiated from the bottom level of such beams at a load approximately 150 kN and propagated with increase in load; whereas the shear cracks started appearing at a load of approximately 350 kN and continued to propagate and widened with the elevated load till the final failure occurred at on an average load of 710 kN. The mode of failure was observed to be shear crushing of the concrete. RESULTS AND DISCUSSION Fig.-8: The crack patterns of Reinforced Concrete Beam (i.e. control beams) Specimens
  15. 18. For specimen F/B-3 which was fully steel fiber reinforced with stirrups, no cracks were visible on the sides of the beam until 200 kN load was reached. On the other hand, diagonal shear crack was observed near the middle of shear spans when the applied load reached at 300 kN level. Finally, the beam failed at a load of 850 kN. It was observed for the fully fiber reinforced concrete beams that in the region of the mid span, flexure cracks were initiated from the bottom level . Fig.-9: The crack patterns of Fully Fiber RC Beam Specimens RESULTS AND DISCUSSION(cont.)
  16. 19. the first crack was occurred at 250 kN at the bottom mid span of the beam. This beam exhibited the first crack at a higher load than the control beam P/B-1 (150kN) due to the presence of the steel fiber, flexure-shear cracks were initiated from the bottom level and continues to propagate with increased load. The corresponding failure load occurred at 750 kN. The enhancement of the failure load was observed which is of the order of average 6% higher in comparison to that of the control beam. The mode of failure was observed to be shear compression of such specimens Fig.-10: The Crack Patterns of 0.5 Depth Level of Fiber RC beam Specimens RESULTS AND DISCUSSION(cont.)
  17. 20. The first crack was seen at 200 kN load level at the bottom mid span of the beam . flexure shear cracks were initiated from the bottom level of such beams at a load of approximately 248 kN and continue to propagate with increasing load. While the ultimate load was recorded as 730 kN with 4% average increase in load capacity over and above the control beam P/B-1. Shear compression mode of failure was observed for such types of beam specimens. Fig.-11: The Crack Patterns of Tensile bar Depth Level of Fiber RC Beam Specimens RESULTS AND DISCUSSION(cont.)
  18. 21. Fig.-13: Load deflection plot of beam specimens in Reinforced Concrete Beam
  19. 22. Fig.-14: Load Deflection Plot of Fully Fiber Concrete Beam Specimens
  20. 23. Fig.-15: Load Deflection Plot of 0.5 Depth Level of Fiber RC beam Specimens
  21. 24. Fig.-16: Load Deflection Plot of Top Level of Tensile Steel Bar of Fiber RC Beam Specimens
  22. 25. Specimen Beam Designation First Crack load (kN) Ultimate load ( kN ) Shear Force ( kN ) Max Mid Deflection (mm) Mode of failure Reinforced concrete beam P/B-1 150 720 360 16 Shear Compression P/B-2 145 710 355 16 Shear Compression P/B-3 150 700 350 15 Shear Compression Fiber reinforced concrete beam F/B-1 310 830 415 13 Shear Compression F/B-2 400 820 410 12 Shear Compression F/B-3 320 840 420 14 Shear Compression 0.5D depth of Fiber level beam 0.5D-B-1 260 740 370 13 Shear Compression 0.5D-B-2 260 770 385 13 Shear Compression 0.5D-B-3 250 750 370 14 Shear Compression The Depth of fiber up to top level of tensile reinforcement Bar beam TL.SB(F)-1 200 720 360 14 Shear Compression TL.SB(F)-2 210 730 365 13 Shear Compression TL.SB(F)-3 200 740 370 14 Shear Compression Table-9: Experimental Results
  23. 26. Fig.-12: Average Ultimate load verses Specimens RESULTS AND DISCUSSION(cont.)
  24. 27.  The FRC beams of all types have shown improvement in terms of first crack load, ultimate load and deflection characteristics when compared to that of the control beam.  The overall performances of all the FRC beams were superior to that of the control beam.  The beam specimen incorporated fully with steel fiber reinforcement has exhibited an increase of average 20 % in ultimate load, when compared to the control beam specimens.  The ultimate shear and bending capacities of all the FRC beams were more than that of the control beam specimens.  For any particular load, the deflection of all such beam specimens was lower than that of the control beam specimens. CONCLUSIONS
  25. 28. RECOMMENDATION  The specimen can be tested under uniformly distributed load (UDL) and compare the behaviors of failure between two point load and UDL.count the elevated of load till the final failure occurred at on both types of loading.  Compare the strength between RC and FRC using different types of mix proportion of Concrete and water cement ratio.  Cost benefit analysis may be done to the uncontrolled (by increasing size) beam specimens for both RC and FRC.
  26. 29. THANKS
Trulli

M.Sc. in Engineering (Structural)
Instructor
Construction Management
Creative Training Center (CTC)

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