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AXIAL BEHAVIOR OF CONCRETE-FILLED STEELTUBULAR BEAM COLUMN JOINT

This paper present the optimization of partial replacement of natural sand by M- sand and recycledcoarse aggregate addition of manufactured sand up to 50% yielded comparable strength withthat of the conventional concrete. Recycled Coarse Aggregate is obtained from the demolitionof building materials. The mechanical properties for various replacements of sand by M-Sandand course aggregate by Recycled Coarse Aggregate were studied. The different concretemixes used were 10, 20, and 30%. The cylinders were casted and tested for 28 days for allreplacements and modulus of elasticity was calculated. Beam column joint in a reinforcedconcrete Moment Resisting Frames is the crucial zone for transfer of loads effectively betweenthe connecting elements (i.e., beams and columns) in RC structure. But, the failure of reinforcedconcrete frames during many earthquakes has demonstrated heavy distress due to shear inthe joints that culminated in the collapse of the structure. Hence the beam-column joints arecasted for various replacements of M-Sand and Recycled Course Aggregate and tested for theseismic behaviour and compared to the model of ANSYS. Concrete Filled Steel Tubular (CFST)members utilize the advantages of both steel and concrete. They comprise of a steel hollowsection of circular or rectangular shape filled with plain or reinforced concrete. Steel membershave the advantages of high tensile strength and ductility, while concrete members have theadvantages of high compressive strength and stiffness. Composite members combine steeland concrete, resulting in a member that has the beneficial qualities of both materials. In thispaper, an attempt was made with steel tubular beam column joint filled with different types ofconcrete using M-Sand and Recycled Course aggregate. The effects of steel tubes, compressivestrength of concrete and the confinement of concrete are examined.

Keywords: CFST, M-sand, Recycled coarse aggregate, Natural sand, Joints, Compressivestrength

1 M.E. Student, Department of Civil Engineering, Nandha Engineering College, Tamil Nadu, India.2 Assistant Professor, Department of Civil Engineering, Nandha Engineering College, Tamil Nadu, India.

INTRODUCTIONConcrete Filled Steel Tubular (CFST)members utilize the advantages of both steel

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Int. J. Struct. & Civil Engg. Res. 2014

Research Paper

and concrete. They comprise of a steel hollowsection of circular or rectangular shape filledwith plain or reinforced concrete. They are

Parvin Barkath M1* and Shankar P2

*Corresponding Author: Parvin Barkath M, Parvin.shafreen@gmail.com

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widely used in high-rise and multistorybuildings as columns and beam-columns, andas beams in low-rise industrial buildings wherea robust and efficient structural system isrequired.

Composite members consisting of squaresteel tubes filled with concrete are extensivelyused in structures involving very large appliedmoments, particularly in zones of highseismicity. Composite square Concrete FilledSteel Tubes (CFST) have been usedincreasingly as columns, beams and beam-columns in braced and un-braced framestructures. Their use worldwide has rangedfrom compression members in low-rise, openfloor plan used in retrofitting of damages steelbridge piers after the 1995 Hyogoken-Nanbuearthquake in Japan and the Northridgeearthquake in 1994 in the USA. The two maintypes of composite column are the steel-reinforcement concrete beam, which consistsof a steel section encased in reinforced orunreinforced concrete, and the Concrete FilledSteel Tubular (CFST) beams, which consistsof a steel tube filled with concrete.

CFST beams have many advantages oversteel-reinforcement concrete beams. Themajor benefits of concrete filled beams are:

• Steel beam acts as permanent and integralformwork,

• The steel beam provides externalreinforcement, and

• The steel beam support several levels ofconstruction prior to concrete beingpumped.

Although CFST beams are suitable for alltall buildings in high seismic regions, their usehas been limited due to a lack of information

about the true strength and the inelasticbehavior of CFST members. Due to thetraditional separation between structural steeland reinforced concrete design, the procedurefor designing CFST beam using the AmericanConcrete Institute’s (ACI) code is quite differentfrom the Load and Factor Resistance Design(LFRD) method suggested by the AmericanInstitute of Steel Construction’s (AISC).

Beam Column JointBeam-column joint is an important componentof a reinforced concrete moment resistingframe and should be designed and detailedproperly, especially when the frame issubjected to earthquake loading. Failure ofbeam-column joints during earthquakes isgoverned by bond and shear failuremechanism which are brittle in nature.Therefore, current international codes give highimportance to provide adequate anchorage tolongitudinal bars and confinement of coreconcrete in resisting shear. A review of thebehavior and design of different types ofbeam-column joints in reinforced concretemoment resisting frame under seismic loadingillustrates that design and detailing provisionsfor the joints in the current Indian seismic code,IS 13920:2001 are not adequate to ensureprevention of such brittle failure. Since jointsare subjected to large shear force duringearthquake, shear strength in this regionshould be adequate to carry this large amountof shear force.

The joint is defined as the portion of thecolumn within the depth of the deepest beamthat frames into the column. In a momentresisting frame, three types of joints can beidentified viz. Interior Joint, Exterior Joint andCorner Joint.

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The severity of forces and demands on theperformance of these joints calls for greaterunderstanding of their seismic behavior. Theseforces develop complex mechanisms involvingbond and shear within the joint.

replacement for the coarse aggregate. It canreuse, recycle the waste materials from theextraction of huge waste. Rapid industrialdevelopment causes serious problems all overthe world such as depletion of naturalaggregates and creates enormous amount ofwaste materials from construction fields. Thusthe recycled coarse aggregate is used as areplacement for coarse aggregate withreduction in cost and increase in strength.

EXPERIMENTALINVESTIGATIONCementOPC 53 grade cement was used for thisinvestigation and the specific gravity of cementwas 3.15. The physical properties of cementare given Table 1.

Figure 1: Types of Joint

Interiorjoint

Exteriorjoint

CornerJoint

Manufacturing SandConventional concrete is a mixture of cement,sand and aggregate. Properties of aggregateaffect the durability and performance ofconcrete, so fine aggregate is an essentialcomponent of concrete. The most commonlyused fine aggregate is natural river sand orquarry dust. Fine and coarse aggregateconstitute about 75% of total volume. Whenrock is crushed and sized in a quarry the mainaim has generally been to produce coarseaggregates and road construction materialsmeeting certain specifications. Generally, thisprocess has left over a proportion of excessfines of variable properties, generally finer than5-mm size.

Recycled Course Aggregate Most of the buildings materials generate solidwastes all over the world due to demolition ofvarious buildings. It was introduced due to thegrowing concern about future of the planet andit applies for construction industry, a hugeconsumer of natural resource. The demolitionof building materials can be used as a

Property Values

Specific gravity 3.15

Initial setting time 30 min

Final setting time 2-3 hours

fineness 3.2%

Table 1: Physical Properties of Cement

Fine AggregateLocally available river sand passed through4.75 mm IS sieve is used as fine aggregate.The specific gravity of sand is 2.45.

Coarse AggregateThe Coarse aggregate are obtained from alocal quarry is used. The coarse aggregatewith a maximum size 20 mm having a specificgravity 2.84 has been taken for mixes.

WaterWater is an important ingredient of concreteas it initiates the chemical reaction withcement and the mix water was completely free

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from chlorides and sulfates. Ordinary potablewater was used throughout the investigationas well as for curing concrete specimens.

Manufacturing SandThe definition of the size of sand particlesvaries, but in general sand contains particlesmeasuring about 0.0025-0.08 inches (0.063-2.0 mm) in diameter. Particles smaller than thissize are classified as silt. Larger particles areeither granules or gravel, depending on theirsize. In the construction business, all aggregatematerials with particles smaller than 0.25inches (6.4 mm) are classified as fineaggregates. This includes sand. Materials withparticles from 0.25 inches (6.4 mm) up to about6.0 inches (15.2 cm) are classified as coarseaggregates.

Recycled Coarse AggregateRecycled Concrete Aggregates have irregularand granular structure, due to the adheredmortar which can be a point of concern as it isa factor which contributes toward higher waterabsorption, workability and ultimately thestrength characteristics of the concrete madeusing RCA. The structure of RCA mainlydepends upon the parent source of concreterubble. While aggregates derived fromconcrete cubes yields aggregates withirregular shape and better bond betweenmortar and aggregate.

MIX PROPORTIONINGThe mix proportions of M20 concrete and mixratio of concrete 0.5: 1: 1.74: 3.3 by weight ofwater, cement, fine and coarse aggregate.

RESULTS AND DISCUSSIONControl SpecimenFor specimen the deformation was very smallwhen it was loaded. When the load reached

to 400 kN the extension in length and diameteris 300 mm and 153 mm respectively. Thespecimen had a visible yield of compressivestrength of 0.023 kN/mm2.

The load versus deflection is as shown inFigure 2.

Figure 2: Load vs Displacement Curve

Figure 3: Stress-Strain Curve

Stress-Strain diagram is as shown inFigure 3.

10% Replacement of M-Sand andRCAIn this case the specimen had the very smalldeformation when it was loaded. When theload reached to 292 kN the extension in lengthand diameter is 293 mm and 152 mm

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respectively. The specimen had a visible yieldof compressive strength is 0.017 kN/mm2.

The load versus deflection is as shown inFigure 4.

Stress-strain diagram is as shown inFigure 7.

30% Replacement of M-Sand andRCAFor specimen the deformation was very smallwhen it was loaded. When the load reachedto 397.16 kN the extension in length anddiameter is 293mm and 152 mm respectively.The specimen had a visible yield ofcompressive strength as 0.023 kN/mm2.

The load versus deflection is as shown inFigure 8.

Stress-strain diagram is as shown inFigure 9.

Figure 4: Load vs Displacement Curve

Figure 5: Stress-Strain Curve

Stress-strain diagram is as shown in Figure 5.

20% Replacement of M-Sand andRCAFor this specimen, the deformation was verysmall when it was loaded. When the loadreached to 395 kN the extension in length anddiameter is 293 mm and 152 mm respectively.The specimen yields the compressive strengthof 0.022 kN/mm2. The load versus deflectionis as shown in Figure 6.

Figure 6: Load vs Displacement Curve

Figure 7: Stress-Strain Curve

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to 30% is done and the tests shows significantimprovement in results which will be used forfuture investigation.

REFERENCES1. Dasgupta P (2000), “Effect of

Confinement on Strength and Ductility ofLarge RC Hollow Sections”, Master ofTechnology Thesis, Department of CivilEngineering, Indian Institute of TechnologyKanpur, Kanpur.

2. Fan Hong and Lihua Xu (2008),“Experimental Studies on MonotonicBehavior of Concrete – Filled SteelSquare Tubular Column – Steel BeamConnection”, The 14th World Conferenceon Earthquake Engineering, October12-17, Beijing, China.

3. IS:13920:2003 (2001), “Indian StandardCode of Practice for Ductile Detailing ofConcrete Structures Subjected to SeismicForces”, Bureau of Indian Standards, NewDelhi.

4. Naveen Hooda, Jyoti Narwal, BhupinderSingh, Vivek Verma and Parveen Singh(2013), “An Experimental Investigation onStructural Behavior of Beam ColumnJoint”, International Journal of InnovativeTechnology and Exploring Engineering(IJRTEE), Vol. 3, No. 3, ISSN: 2277-3075.

5. Priyanka A Jadhav and Dilip K Kulkarni(2012), “An Experimental Investigation onthe Properties of Concrete ContainingManufactured Sand”, InternationalJournal of Advanced EngineeringTechnology (IJAET), Vol. III, No. II,pp. 101-104.

Figure 8: Load vs Displacement Curve

Figure 9: Stress-Strain Curve

FUTURE INVESTIGATIONThe behavior of CFST beam- column joint willbe studied through casting of T-Section andapplying two point loads for beams and axialload for columns. The test results will be judgeagainst with the ANSYS software.

CONCLUSIONThe overall strength of concrete linearlyincreases from 0% to 30% in the order of 10%increase in the replacement of natural sandby manufactured sand is compared withreference mix. Also partial replacement ofcoarse aggregate with recycled coarseaggregate and fine aggregate with m-sand up

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6. Uma S R (2004), “Seismic Behavior ofBeam Column Joints in Moment ResistingReinforced Concrete Frame Structures”,

Submitted to Indian Concrete Journal,October.