SSRG International Journal of Civil Engineering (SSRG-IJCE) – EFES April 2015
Effect of Grade of Concrete on the Strength of BeamColumn Joint
Shabnum Qayoom#1, Ravi Kumar*2
#
*
P.G Scholar, Department of Structural engineering, SDDIET, (Kurkshetra university, Kurukshetra), Haryana, India.
Assistant Professor, Department of Structural Engineering, SDDIET, (Kurukshetra University,Kurukshetra), Haryana, India
Abstract- Beam-column joint is a point where beam and
column intersect. A joint is a critical point in a structure
were moments, shears and direct loads act. There are
various types of joints in a structure. They are classified
as corner joints, exterior joints, interior joints, etc. In the
last few decades earthquakes of many magnitudes have
struck in different countries of the world which cause
severe damage to reinforced concrete structures. The
most critical point are zone were affective transfer of
loads take place is beam column joint. During the past
decades many buildings mainly RCC structures behaved
poorly because of the poor behavior of beam column
joint. Shear failure of beam column joint is not accepted
in any condition because shear failure is a kind of brittle
failure. In this paper we are going to test external and
internal type of joint by changing the grade of concrete at
joint and reducing some percentage of special confining
reinforcement. Our main aim will be to increase the
shear resistance of the joint which in turn will reduce the
chances of brittle failure. Increasing the rigidity by
changing the grade of concrete will increase the shear
performance of the joint under forces.
according to some standard codes. At beam-column joints
special reinforcement is to be provided in addition to the
normal reinforcement, proper anchorage length is to be
provided in the form of bends for anchorage purposesin case
of external joints. So due to the provision of special
reinforcement, normal reinforcement and anchorage
reinforcement there is congestion of steel at the joints.
Due to the congestion of steel there is problem in
compaction of concrete which prevents the concrete to attain
full compressive strength, compaction is necessary for
expelling the entrapped air from the concrete, if this
entrapped air is not removed fully, the concrete loses
strength considerably which eventually will decrease the
shear strength of joint. It has been experimentally shown that
greater the percentage of voids, less will be the strength of
concrete, 5 percent voids reduce the strength of concrete by
about 30 percent and 10 percent voids reduce the strength by
over 50 percenthence, we will decrease the percentage of
special confining reinforcement and will replace it with
higher grade of concrete at the joint as compared to rest of
specimen. This will increase the rigidity ofjoint and prevent
shear failure or brittle failure of the joint. Beam-column joint
Keywords- Beam column joint, rigidity, grade of concrete
shear strength, water cement ratio, special confining
reinforcement, compressive strength, stress-strain.
I. INTRODUCTION
Beam column joints when designed needs utmost care while
designing them because a beam column joint is subjected to
one are more forces at a time. Beam columns are designed
II. .REVIEW OF LITERATURE
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The method proposed in this paper is aimed at improving the
shear strength of joint by changing the grade of concrete at
joint and checking its strength.Strenth of joint cannot be
determined by analytical model and need to be determined
by the experimental methods. Exterior and interior joint
models will be tested under loading frame and their strength
determined
The strength of beam column junction plays a very important
role in the strength of structure; a literature review is carried
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SSRG International Journal of Civil Engineering (SSRG-IJCE) – EFES April 2015
about the rigidity and shear strength of the beam column
joint.
“rigidly” connected in such a way as to ensure that they all
undergo the same rotation under the action of loads.
SudhirK.Jain, R.K. Ingle and GoutamMondal (2006)[1] in
this paper the shear strength of beam column which is not
safe in shear can be increased by increase of column section,
increase of the size of the beam section and increase of the
grade of concrete. The later alternative will increase the
rigidity or shear strength of joint and will also reduce the
steel required in columns.
In RC buildings, portions of columns that are common to
beams at their intersections are called beam- column
joints.Since their constituent materials have limited
strengths, the joints have limited force carrying capacity.
When forces larger than these are applied during
earthquakes, joints are severely damaged. Repairing
damaged joints is difficult, and so damage must be avoided.
Thus, beam-column joints must be designed to resist
earthquake effects.
G.Maariappanand, R.Singaravadivelan (2013) [2] in this
paper behavior of RCC beam column joint retrofitted with
Basalt fiber reinforced polymer sheet was carried out. The
performance
of
retrofitted
specimen
was good when compared with the performance of
specimens as designed according to IS 456:2000 and
detailing as per IS 13920:1993.
[3]
S UnnikrishnaPillai, DevdasMenon (2012) , in the text
book Reinforced Concrete Design, Congestion of steel
should be avoided at locations where members intersect,
such as intersections beams with girder(primary beam) and
girders with column. In the interior beam-column joint
,generally there is overcrowding of the negative steel in the
beam if they are all placed within the beam width .This
usually interferes with the proper placing and compaction of
the concrete at joint. The bond developed in these top
reinforcement also is relatively inferior.
Naveen
Hooda,
JyotiNarwal,
Bhupinder
Singh,
[4]
VivekVerma,Praveen Singh(2013) ,in this paper an
experimental investigation on structural behavior of beamcolumn joint with steel fibres in the concrete mix improved
structural performance of beam-column joints measured in
terms of ultimate load carrying capacity, stiffness ,crack
width, deflection and curvature ductility factor. Steel fiber
reinforced concrete is one of the alternative solutions for
reducing the congestion of transverse reinforcement in beam
column joints. Thus with the reduction of reinforcement in
the joint core helps in the ease of construction difficulties.
Reversal of moments at joints should be also taken into
consideration while designing beam-column junction
IV. MATERIALSTO BEUSED
The materials to be used for the test will be steel, concrete of
different grades. Wooden or steel moulds will be used to cast
the specimen, gunny bags for curing, etc.
A.Steel
The steel bars of grade Fe415 and Fe500 will be
used for making the specimen. The number of the grade
indicates the yield stress.Fe415 is mostly commonly used
steel nowadays among the two. The steel bars are available
in different ranges of diameter from 6mm to 50mm.
However, those having diameter from 6mm to 20mm are
used for home construction.
B.Concrete of different Grades
Concrete is a composite material composed mainly
of water, aggregates and cement. Often additives and
reinforcements are included in the mixture to achieve the
desired physical properties of the finishing material. We
refer the grade of concrete as M10, M15, M20, M25, M30,
etc. where M represents the Mix Design and numerical value
implies the 28 days characteristic compressive strength.
Different grades of concrete will be used in the study to
calculate the strength of joint.
C.Steel Moulds or Wooden Moulds
III. FRAMED CONSTRUCTION
Framed construction generally composes of columns and
beam. Their ability to resist lateral loads is entirely due to the
rigidities of the beam and column connections and the
moment-resisting capacities of the individual members. They
are often (albeit mistakenly) called “rigid frames” because
the ends of the various members framing into a joint are
ISSN: 2348 – 8352
Steel moulds or wooden moulds resembling the
shape of exterior joint and interior joint will be used to cast
specimen for testing purposes. Steel mould will be welded if
used whereas wooden mould will be prepared by nailing
plain wooden sheets of certain minimum thickness.
D. Gunny Bags
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SSRG International Journal of Civil Engineering (SSRG-IJCE) – EFES April 2015
Gunny bags will be used for curing purpose .Curing
is a very important step in the study because the quick
surface drying of concrete results in the movement of
moisture from interior to the surface .This steep moisture
gradient cause high internal stresses which leads to the
internal micro cracking in the semi-plastic concrete.
V.ABOUT THE SPECIMEN
Four specimens simulating the shape of exterior joint and
interior will be tested for the strength or rigidity of the joint.
Two specimens will be designed and detailed according to
the IS 456:2000 and IS 13920:1993 while as two specimens
will be designed and detailed by using high grade of concrete
at the joint zone as compared to rest of the specimen and by
decreasing joint reinforcement to some percentage. Grades
of concrete up to M35 will be used in making the specimen.
VI. FUTURE WORK AND TESTING
The specimens will be tested on a loading frame for
calculating the rigidity of the joint. Analysis of the specimen
will be also done on the basis of calculating rigidity and
deflection.
After testing is done, Critical load and rigidity of the joint
will be calculated by using Stress-Strain curves and
Moment-Curvature curves.
The specimen can be tested for Static as well as Monotonic
loading. If the rigidity of the joint comes out to be low as
compared to the specimens designed and detailed according
to IS 456:2000 and IS 13920:1993 then higher grade of
concrete will be used in the joint zone till desired rigidity or
strength is achieved.
VII. CONCLUSION
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The rigidity of joints with higher grade of concrete and
rigidity of normal joints will be compared.
Stress –Strain curves will be plotted to work out the
critical or failure loads.
Critical loads for all the specimens will be worked out.
REFERENCES
[1] SudhirK,Jain ,R.K.Ingle and GoutamMondal (2006). Proposed codal
provisions for design and detailing of beam-column joints in seismic
regions.
[2]G.Maariapppan and R.Singaravadivelan (2013). Studies on Behaviour of
Rcc Beam-Column Joint Retrofitted with Basalt Fiber Reinforced Polymer
Sheet.
[3] S UnnikrishnaPilla and DevdasMenon (2012). Reinforced Concrete
Design,3rd edition, Tata McGraw Hill Education Private Limited, New
Delhi, India.
[4] Naveen Hooda, JyotiNarwal, Bhupinder Singh, VivekVerma, Praveen
Singh (2013),Experimental Investigation on Structural Behaviour of Beam
Column joint.
[5] Indian Standards (IS 13920-1993). Ductile Detailing Of Reinforced
Concrete Structures Subjected To Seismic Forces-Code Of Practice.
[6] Ashok K.Jain (2010). Reinforced Concrete
Design,6thedition,Nem Chand &Bros,Roorkee,India.
Limit
State
[7] PankajAgarwal and Manish Shrikhande (2012).Earthquake resistant
design of structures, PHI Learning Private Limited, New Delhi, India
[8] P.C. Varghese (2012.)Avanced Reinforced Concrete Design,2nd edition,
PHI Learning Private Limited, New Delhi, India.
[9]S.S.Patiland S.S. manekari (2013). A Study of Rcc Beam –Column
Connections Subjected to Monotonic Loading.
[10] Indian standard (IS 456:2000). Plain and Reinforced Concrete-Code of
Practice
[11]Hyderabad
India
Online-Real
[online].Availablehttp://Hyderabad-india-online.com/realestate/2011/05/quality-of-steel-home
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