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Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
Upgradation of non ductile reinforced concrete beamcolumn connections using fibre
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Upgradation of non ductile reinforced concrete beamcolumn connections using fibre

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  • 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME TECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 3, Issue 2, July- December (2012), pp. 241-250 IJCIET© IAEME: www.iaeme.com/ijciet.htmlJournal Impact Factor (2012): 3.1861 (Calculated by GISI) IAEMEwww.jifactor.com UPGRADATION OF NON-DUCTILE REINFORCED CONCRETE BEAM- COLUMN CONNECTIONS USING FIBRE Priti. A. Patel Research scholar, Applied Mechanics Department, S. V. National Institute of Technology, Ichchhanath, Surat-395 007, Gujarat, India. E-mail: pritipranay@gmail.com Dr. Atul K. Desai Professor, Applied Mechanics Department, S. V. National Institute of Technology, Ichchhanath, Surat-395 007, Gujarat, India. Email: akd@amd.svnit.ac.in Dr. Jatin A. Desai Retire Professor, Applied Mechanics Department, S. V. National Institute of Technology, Ichchhanath,, Surat-395 007, Gujarat, India. Email: Jatin.desai@utu.ac.in ABSTRACT This paper presents an experimental investigation to determine the performance characteristics of non-ductile reinforced concrete (RC) beam-column connection by using polyester fibre. A number of studies have been reported on steel fibre reinforced concrete beam-column connections. Now a day’s synthetic fibres start to capture the market in all over the word and becoming popular for engineering application. The attempt has been made to use polyester fibre of triangular cross-section for RC element. An experimental investigation was made to study the behaviors of polyester fibre reinforced concrete (PFRC) beams-column connection under cyclic loading. Fibre dosages used were 1%, 1.5% and 2% by volume. The test program included the evaluation of non-ductile PFRC beam-column connection in terms of load-deflection behaviour, energy dissipation, stiffness and specific damping capacity. The test results reveal that addition of polyester fibre in the connection region of beam and column enhances all the above properties. The 241
  • 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEincrease in strength is about 31% that of non-ductile control specimen. The energydissipation capacity and rate of degradation of stiffness greatly improve.Key Words: Reinforced concrete, beam-column, connection, fiber, strength, stiffness1. INTRODUCTIONReinforced concrete (RC) beam-column connections have been identified as potentiallyone of the weaker components. The reinforced concrete structures that have beendesigned without seismic provision i.e. non-ductile represents involves technical issues.Because such structures were originally designed to carry gravity loads, they lack theductility and strength that induces failure mechanism under earthquakes. The intrinsicproblem of normal concrete is its brittle nature. Normal concrete looses resistance afterthe formation of multiple cracks. To achieve ductility in these circumstances; reinforcingconcrete using discrete fibres, randomly arranged, is an acceptable solution to improvethe properties of normal concrete. These enhancements in material properties have pavedthe way for more research in this area to explore its advancement into unused areas.There are many kinds of fibers, no matter metallic or polymeric, widely used in concreteengineering for their advantages. Commonly used fibres are mainly steel, glass, carbon,and synthetic. It is well known fact that concrete is relatively a brittle material and addingrandomly distributed short fibres may improve the toughness of cementatious matrices bypreventing or controlling the initiation, propagation or coalescence of cracks (Mobasher1990 ; Soroushian 1992). The function of short-cut fibres as secondary reinforcement inconcrete is mainly to inhibit crack initiation and propagation (Ramakrishnan, 2000). Thebasic purpose of using fibres is to control cracks at different size levels, in different zonesof concrete (cement paste or interface zone between paste and aggregate), at differentcuring ages and at different loading stages. The use of fiber reinforced concrete (FRC)has steadily increased during the last two decades and its current field of applicationincludes: airport and highway pavements, earthquake-resistance and explosive-resistantstructures, mine and tunnel linings, bridge deck overlays, hydraulic structures, rock-slopestabilization.2. RESEARCH SIGNIFICANCEA number of studies have been reported on the steel fiber reinforced concrete (SFRC)with particular reference to improvements in cracking resistance, shear capacity, impactresistance, resistance to abrasion with the addition of steel fibers (Suji et.al., 2007). Nowa day; synthetic fibres such as polyester polypropylene, polythelyne etc. capture the one –third of market in the world and becoming popular for engineering application due totheir some unique properties like low density, chemically inert and non corrosive. Veryfew literatures are available for polyester fibre reinforced concrete. This paper reports 242
  • 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEexperimental study carried out to investigate the behavior of PFRC beam-columnconnection under cyclic loading.3. EXPERIMENTAL PROGRAMME3.1 Specimen DesignA one-third scale first floor exterior beam-column connection was considered from thefour storeys building which was designed as per Indian standard code of plain andreinforced concrete. The overall dimensions and reinforcement details are shown in fig.1.Four exterior beam-column connections were considered for experiment work such as 1.Non-ductile control specimen (ND) i.e. 0% fibre 2. Non-ductile PFRC specimens: (a)PFRC specimen with 1% fibre (b) PFRC specimen with 1.5% fibre (c) PFRC specimenwith 2% fibre. For all PFRC specimens polyester fibres were provided only in the jointand region of beam and column where ductility is demanded (refer fig. 1). Figure 1 Overall dimensions and reinforcement details of specimen 243
  • 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME3.2 Material PropertiesThe concrete mix proportions were (1: 3.2:1.57:0.5) by weight of cement, coarseaggregate, fine aggregate and water respectively. The average compressive strength ofcontrol concrete was 32.29 MPa. Polyester fibre of length 12mm was used as it exhibitgood bond with cement being substantial triangular in cross section and offer betterdispersion in the matrix being silicon coated. The common forms of these fibres aresmooth-monofilament and having density of 1400 kg/m3 respectively. Super plasticizer –140 ml/bag is used to achieve adequate fiber dispersion and workability. Thecompressive strength of PFRC of 1%, 1.5% and 2% fiber volume fraction were 35.18MPa, 37.1 MPa, and 37.52 MPa respectively.3.3Test SetupThe specimen represents the part of the exterior connection of a building isolated at theassumed inflection points (i.e. midspan of beams and columns) when the building issubjected to lateral loads. The test setup is shown in figure 2. The top and bottom of thecolumn was fixed between hinged connections. The column axial load was appliedthrough hydraulic jack of capacity 1000 kN to kept the column in position during testing.Cyclic lateral loads were simulated by hydraulic jacks mounted vertically at the end ofthe beams. The cyclic loading consisted of a simple history of reversed symmetricdisplacement of increasing amplitudes 5mm, 10mm, etc. up to failure. A LVDT ofcapacity 150 mm with least-count of 0.001 mm was used to measure the beam tipdisplacement. Load cell indicator and LVDT indicator were used to note down readingsof load applied at the tip of beam and displacement of tip of beam. Figure 2 Experiment setup 244
  • 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME4. PERFORMANCE OF THE SPECIMEN4.1 Load – displacement behaviourThe load-displacement loops were plotted from the recorded data of the applieddisplacement at beam tip and corresponding load. This load – displacement graphs wereused to evaluate performance of specimens under cyclic load such as ultimate strength,capacity of energy dissipation through ductility, stiffness degradation and dampingcapacity. The load – displacement graphs of non-ductile control and non-ductile PFRCspecimens are shown in figure 3(a) to (d). Figure 3 (a) ND Figure 3 (b) NDP1 Figure 3 (c) NDP2 Figure 3 (b) NDP3 Figure 3 (a) to (d) Load –displacement graph for beam-column connections 245
  • 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME4.2 Ultimate StrengthFor control specimen, the behaviour was very weak it resists the maximum load of 25.79kN in pushing and 21.82kN in pulling. This is because specimens are designed to resistgravity load and not detailed to resist lateral load. The strength in pushing was slightlyhigher than that in pulling due to unequal top and bottom reinforcement. The technique ofaddition of polyester fiber used in this study was found effective in increasing the cyclicloading capacity of all PFRC specimens. Figure 4 and table 1 shows that the capacity ofPFRC specimens to resist load and displace large without extensive cracking (i.e. ductilebehaviour) was found approximately 8 to 31% higher than control specimen. Table 1. Ultimate strength and cumulative energy dissipation of specimens First Ultimate load Pu % difference Energy crack (kN) Mode ofSpecimen Dissipation load Pcr failure Push Pull Push Pull (kN.m) (kN) ND 10.06 25.79 21.82 - - 3.53 J NDP1 10.89 27.80949 23.46439 7.84 7.52 15.69 J NDP2 12.21 30.78006 25.96439 19.36 18.98 18.89 J NDP3 13.9 33.89363 28.7212 31.43 31.61 22.58 B-JND = Non-ductile control specimen with 0% polyester fibre, NDP1 = Non-ductile with 1% polyester fibre,NDP2 = Non-ductile with 1.5% polyester fibre, NDP3 = Non-ductile with 2% polyester fibre,J = Joint shear failure, B-J = Beam flexure and joint shear failure Figure 4 Ultimate loads for different test specimens 246
  • 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME4.3 Energy DissipationThe load-displacement loops were plotted from theThe amount of cumulated energy of a beam-column connection subjected to cyclicloading was calculated as the area under the peak value of the beam tip force -displacement loop up to the related displacement level as given in figure 3 (a) to figure 3(d). As a measure of ductility, energy absorption capacities of the specimens wereevaluated and compared. For control specimen the tip displacement of the beam reached35 mm. The specimens while PFRC specimen’s show tip displacement of the beam up to50mm. The dissipated energy for PFRC specimens showed an increasing trend asdisplacement level increases. This showed that use of the PFRC in the beam-columnconnection increased the amount of cumulated energy. Figure 5 and table 1 shows thetotal amount of dissipated energy capacities of all specimens. The control specimen NDabsorbed less energy than those of PFRC specimens and displayed more brittlebehaviour. The best energy dissipated by NDP2 specimen. Figure 5 Cumulative energy dissipation for different test specimens4.4 StiffnessThe secant stiffness in each cycle was calculated using line drawn between the maximumpositive displacement point in half of the cycle and maximum negative displacementpoint in the half of the cycle. This stiffness was used to provide a qualitative measure ofthe stiffness degradation in the specimen. In figure 6 the degradation of stiffness isplotted versus the corresponding displacement cycle for all specimens. Figure 9 alsoshow that the stiffness degradation rates decreases in PFRC specimens than controlspecimen ND. This is due to the use of polyester fibres which provide extra confinementto the cracked regions in the joint region and resulted in more ductile behavior. 247
  • 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME Figure 6 Stiffness degradation for different test specimens4.5 Specific Damping CapacitySpecific damping capacity is the ratio of dissipated energy to applied energy. Specificdamping capacity (SDC) increases as the displacement cycle increases for all specimens,because energy dissipation also increases with displacement in case of all specimens.Variations in SDC with respect to the different cycles are shown in figure 7 Generalbehavior of figure 7 reflected that SDC was increased with displacement. Figure 7 specific damping capacities for different test specimens 248
  • 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME5 CONCLUSIONSThe following conclusions were drawn from the experimental results presented in thispaper:1. Ultimate strength capacity of beam-column connection increased with the increasing fibre volume fraction.2. The PFRC beam-column connections undergo large displacement (50 mm) than non- ductile control specimen (35mm).3. The PFRC specimens not developed wider cracks; this indicates that polyester fibers impart ductility to the beam-column connection.4. Addition of polyester fibre decreases the stiffness degradation rate of PFRC specimens than control specimen ND.5. The energy dissipation of control specimen ND was very poor; while energy dissipation exhibited by all PFRC specimens is better than ND. This also indicate that polyester fibre impart ductility which is the essential properties for the beam-column connection.References1) Bayasi Ziada and Gebman Michael (2002), “Reduction of Lateral Reinforcement in Seismic Beam-Column Connection Via Application of Steel Fibers”, ACI Structural Journal, Vol. 99, pp. 772-780.2) Bayasi Zinda and Zeng (1993), “Properties of polypropylene fiber reinforced concrete”, ACI Material Journals, Vol. 90, No.6.3) Bindhu K.R. and Jaya K.P.( 2008), “Performance of Exterior Beam-Column Joints with Cross-Inclined Bars under Seismic Type loading”, J. of Engg. And Applied science, Vol.3, pp. 591-597.4) Chen Pu - Woei, Chung D. D .L(1996), “A Comparative Study of Concretes Reinforced with Carbon, Polyethylene, and Steel Fibers and Their Improvement by Latex Addition”, ACI Material Journal, Vol. 93, pp. 129-133.5) Fenwick Richard, Megget Les (2003), “Seismic Performance of External reinforced Concrete Beam - Column Joints”, Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 36, pp. 223-232.6) Filiatrault A., Pineau S, Houde J. (1995), “Seismic Behaviour of Steel-Fiber Reinforced Concrete Interior Beam-Column Joints”, ACI Structural Journal, Vol. 92, pp. 543-552.7) Gustavo J. Parra - Montesinos, Peterfreund Sean W., Chao Shih-Ho (2005), “Highly Damage-Tolerant Beam-Column Joints Through Use of High-Performance Fiber-Reinforced Cement Composites”, ACI Structural Journal, Vol. 102, pp. 487-495.8) Hwang Shyh-Jiann, Lee Hung-Jen, Liao T., Kuo-Chou (2005), “Role of Hoop on Shear Strength of Reinforced Concrete Beam-Column joints”, ACI Structural Journal., Vol. 102, pp. 445-453. 249
  • 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME9) Joint ACI-ASCE committee 352, (2002), “Recommendation for Design of Beam-Column joints in Monolithic Reinforced Concrete Structures (ACI 352 R-02)”, American Concrete Institute, Farmington Hills, Mich., pp. 37.10) Lin Cheng-Ming , Restrepo Jose I.( 2002), “Seismic Behaviour and Design of Reinforced Concrete Interior Beam-Column Joints”, Bulletin of the New Zealand Society for Earthquake Engineering, V. 35, pp. 108-128.11) P. Asha and R. Sundarajan, (2006), “Evaluation of Seismic Resistance of Exterior Beam-Column Joints with Detailing as Per IS 13920 : 1993”, The Indian Concrete Journal, pp. 29-34.12) Shannag M. J., Nabeela Abu - Dyya and Ghazi (2005), “Lateral Load Response of High Performance Fiber Reinforced Concrete Beam-Column Joints”, Construction and Building Materials, Vol. 19, pp. 500-508.13) Suji D., Natesan S. C., Murugesan R. (2007), “Experimental study on behaviors of polypropylene fibrous concrete beams” Journal of Zhejiang University SCIENCE A, Vol. 8(7), pp. 1101-1109.14) Tang Jiuru, Hu Chaobin and Yang Kaijian, (1992). “Seismic Behavior and Shear Strength of Framed Joints using Steel-Fiber Reinforced concrete”, Journal of Structural Engineering, V.118, No. 2, pp 341-357. 250

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