ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRC

ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRC

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  ENHANCEMENT OF SEISMICPERFORMANCE OF STRUCTURES USING HyFRC by Needhi Kotoky Under the supervision of Dr. Anjan Dutta and Dr. Sajal K. Deb Department of Civil Engineering Indian Institute of Technology Guwahati 1
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  MOTIVATION 2  Concrete isthe most widely used construction material  Improve performance of earthquake resistant structures are good ductility and higher energy absorption capacity NCCE-2017  Brittleness of concrete can be overcome by the inclusion of randomly distributed fibres
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  USE OF FRC Use of fibres in concrete removes weaknesses of concrete-  low crack growth resistance  high shrinkage cracking  low durability, etc  The use of two or more types of fibres in suitable combinations helps to arrest crack from micro to macro level  Using mixes incorporating different types of fibre is therefore advantageous 3NCCE-2017
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  USE OF HyFRC 4 Commonlyused fibers for Hybrid Fibre Reinforced Concrete (HyFRC) are-  Steel  Glass  Synthetic fibres like- Polypropylene, Polyester  Carbon fibre  For the present study, Steel fibre of two sizes and Polypropylene fibre of two different brands available in India are used NCCE-2017
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   Inclusion ofsteel fibres in the concrete mix is an effective way of reducing macro-cracking, whilst polypropylene fibres are very good at arresting micro-cracking  Enhance impact strength and toughness  Better fibre proportion is judged on the basis of toughness Fibers bridging crack in a HyFRC tested beam ADVANTAGE OF HyFRC 5NCCE-2017
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  Material characterization forHyFRC  Evaluation of best possible combinations based on toughness of concrete considering prism specimens OBJECTIVE OF THE RESEARCH 6 The research aims to provide an enhanced understanding on the use of HyFRC on the seismic performance of prism specimen NCCE-2017
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  Fibres Aspect ratio Tensile strength (MPa) Geometry Steel fibre (Dramix65mm and 35mm) 65 1150 Hooked end FIBRES USED IN TESTING 7NCCE-2017
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  Fibres Aspect Ratio Tensile strength (MPa) Geometry Polypropelene fibreI (Recron 3s) 600 450 Triangular flat Polypropelene fibre II (Bajaj Plast) 550 670 Fibrillated (Mesh) FIBRES USED IN TESTING 8NCCE-2017
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  FIBRE PROPORTION 9 Fibre Mix Steel (%) PP (%) Type1 PP (%) Type 2 PL - - - A1 0.8 0.15 - A2 0.8 0.2 - A3 1 0.15 - A4 1 0.2 - A5 1.2 0.15 - A6 1.2 0.2 B1 0.8 - 0.15 B2 0.8 - 0.2 B3 1 - 0.15 B4 1 - 0.2 B5 1.2 - 0.15 B6 1.2 - 0.2 NCCE-2017
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  MIXING PROCEDURE FORDIFFERENT CONSTITUENTS 10NCCE-2017
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  COMPRESSIVE STRESS-STRAIN CURVE 11NCCE-2017
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  TENSILE STRESS- STRAINCURVE 12NCCE-2017
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  ASTM C 1018 13NCCE-2017
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  TOUGHNESS EVALUATION 14 Concerns withASTM C 1018 and JSCE SF4 for toughness calculation–  Locating first crack point on the curve is highly subjective and as such toughness indices measured by ASTM C 1018 are highly operator dependent  JSCE produces toughness parameter that is too broad and hence unable to distinguish between composite responses at different crack openings Technique proposed by Banthia and Trottier-  Post Crack Strength (PCS) method produces toughness parameter that do not require the identification of first crack  Calculated from post peak energy  Pre-peak energy is omitted for calculation  Total energy also not requiredNCCE-2017
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  15 POST CRACK STRENGTHMETHOD (PCS) NCCE-2017
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  TEST SET UP 16 150 x 150 x 700 mm beam specimen is tested under three point loading according to ASTM C 1018 to evaluate toughness of the specimen by the PCS method.  HyFRC specimen showed better flexural strength than conventional concrete specimen NCCE-2017
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  VeeBee Time (sec) Maximum load withstand by thespecimen (KN) Modulus of rupture (Mpa) 15 29.8 6.2 RESULTS 17 VeeBee Time (sec) Maximum load withstand by the specimen (KN) Modulus of rupture (Mpa) 2 18.4 3.8 Conventional concrete specimen HyFRC specimen NCCE-2017
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  LOAD-DEFORMATION CURVE 18  Conventionalconcrete fails suddenly once the deflection corresponding to the ultimate flexural strength is exceeded  HyFRC continues to sustain considerable load even when deflection is considerably in excess of the fracture deflection of the conventional concrete HyFRCCONVENTIONAL CONCRETE NCCE-2017
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  TOUGHNESS EVALUATION OFTHE PRISMS 19NCCE-2017 Specimen Type Average compressive strength (MPa) Maximum load applied to the specimen (KN) Toughness (MPa) Modulus of rupture (MPa) PL 34.23 18.27 0.34 3.9 A1 34.96 24.8 2.47 5.8 A2 33.65 27.44 2.67 5.7 A3 35.31 28.16 2.97 6.7 A4 34.22 20.18 2.11 4.9 A5 33.44 25.82 2.54 5.6 A6 34.6 25.07 2.57 5.7 B1 34.04 19.54 1.91 4.8 B2 34.65 17.98 1.87 5.1 B3 33.98 20.73 2.22 5.8 B4 34.17 22.32 2.45 4.3 B5 33.34 23.41 2.53 5.1 B6 34.16 25.1 2.61 5.2
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  20  Fractures specimenof HyFRC shows that failure takes place primarily due to fiber pull-out or debonding  Unlike conventional concrete, HyFRC specimen does not break immediately after initiation of first crack  This has the effect of increasing work of fracture referred as toughness – represented by area under the load-deflection curve  Influence of fibres on concrete is reflected by flexural strength  Best proportion is found to be 1% steel and 0.15% polypropelene (Recron 3s) in term of toughness NCCE-2017 CONCLUDING REMARKS
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   Soleimani, S.S.(2002). Flexural response of hybrid fiber cementitious composites. Master thesis, The university of British Columbia  Banthia, N., Trottier, J.F. (1995). Test methods for flexural toughness characterization of fiber reinforced concrete: some concerns and a proposition. ACI Materials Journal, vol. 92, no. 1, pp. 48-57.  Bentur, A., & Mindess, S. (2006). Fibre reinforced cementitious composites. CRC Press.  American Concrete Institute. (2002).State-of-the-Art Report on Fiber Reinforced Concrete. ACI 544.1R-96  Banthia, N., Soleimani, S.M. (2005). Flexural response of hybrid fiber reinforced cementitious composites, ACI Materials Journal, vol. 102, no. 5.  American Society for Testing and Materials. (1989). Standard Test Method for Flexural Toughness and First-Crack Strength of Fiber Reinforced Concrete (Using Beam with Third Point Loading). ASTM Standards for Concrete and Aggregates, vol. 04.02, Standard 21 REFERENCES NCCE-2017
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   Qian, C.X.,Stroeven, P. (2000). Development of hybrid polypropylene-steel fibre-reinforced concrete, Cement and Concrete Research, vol. 30 , pp. 63–69  Sivakumar,A., Manu Santhanam,M. (2007). Mechanical properties of high strength concrete reinforced with metallic and non- metallic fibres. Cement & Concrete Composites, vol. 29 , pp. 603– 608  Ganesan,N., Indira,P.V., Sabeena,M.V. (2014). Behaviour of hybrid fibre reinforced concrete beam–column joints under reverse cyclic loads. Materials and Design, vol. 54 ,pp. 686–693  Japan Concrete Institute. (1983). Method of Test for Flexural Strength and Flexural Toughness of Fiber Reinforced Concrete. Standard SF4, JCI Standards for Test Methods of Fiber Reinforced Concrete, pp. 45-51. 22 REFERENCES NCCE-2017
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  23 NCCE-2017