Experimental Investigation of Reinforced Concrete Beam with Opening for Combined Bending and Shear

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 824
EXPERIMENTAL INVESTIGATION OF REINFORCED CONCRETE BEAM
WITH OPENING FOR COMBINED BENDING AND SHEAR
Rohit Vyas, Dr.Sanjay kulkarni, Nikhil Landge
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Abstract - In the modern method of construction of
building, pipes and ducts for services like water supply,
sewage, air conditioning, electricity,telephoneandcomputer
networks are to be placed in appropriate positions. Usually,
these pipes and ducts are connected and kept below the
beam soffit and for aesthetic purpose these are covered by
false ceiling thus introducing the dead space. This research
aims at providing transverse openings in the beam so that
the utility pipes and service ducts can be passed through the
opening which may result in systematic accommodation of
pipes and ducts and also provide economic savings in the
construction of multi-storey buildings. Thispaperdealswith
the analysis and design of suchbeamsundertheloadingcase
of bending and shear.
Index Terms - ANSYS, voided beam, transverse
openings, normal stresses, deflection, compressive
strength.
1 Introduction
For modern construction, the provision of providing
transverse openings in the reinforced concrete beam would
be a facility to allow the passage of utility pipes and ducts
through the structure. This type of design would provoke
and promote the structural designers to lower the height of
the structure and to make structure better in design and at
economical cost. In case of small buildingsthesavingswould
not be significant, but in case of high rise building savings in
a single storey multiplied by no. of stories would result in
substantial savings in total height, length of electrical wires
and ducts, air conditionerpipes,plumbing material,partition
surfaces and load on foundation. Due to theabruptchange in
the cross section of the beam and introduction of opening in
the beam the normal beam behaviour would change to a
complex one. The opening corners would subject to high
stress which would lead to crackingofbeams.Alsoreduction
in the stiffness of the beam would lead to excessive
deflection under the service load. Thusproperdetailingwith
sufficient amount of special reinforcement is to be provided
for such beams to avoid the adverse effects on the strength
and serviceability of the beam. Presentlynodesigncriteria is
been mentioned in any of the code which is used for design
of concrete building structure.
2 METHODOLOGY
An experimental investigation is to be carried of reinforced
concrete beam with openings for combined bending and
shear. The specimens of reinforced concrete beam with and
without openings are to be casted. Casting and testing is
been done at the TOM (testing of material) lab of Dhole Patil
college of Engineering under the guidance of Mrs. Pranjali
Kulkarni, HOD, civil department. The values of the peak load
and maximum deflection are recorded. Similar specimens
are also designed analytically in finite element tool ANSYS
and the values of the maximum stress and deflection are
obtained. According to these values the appropriate
designing of the reinforcement is done in the beams and
tested. Methods of analysis are:
A. Analytical approach using FEM tool ANSYS.
B. Experimental testing of beams.
3 EXPERIMENATL WORK
3.1 COMPRESSIVE STRENGTH OF CONCRETE
Cubes of standard size 150x150x150mm size are castedand
tested practicallyforitscrushing/compressivestrengthsoas
to validate the strength of M25 grade concrete. In total 27
cubes are casted. 9 cubes are casted per day out of which
each set of 3 is tested on 3rd, 7th and 28th day respectively.
The average values of 3, 7, 28 days is calculated. Average
values of the strength obtained of all the cubes are shown in
table 1 followed by its graphical representationseeninFig.1.
Fig.2 shows the casted cubes followed by its testing as
shown in Fig.3.
Table 1
Average values of the compressive strength of
cubes
3 days 19.32 N/mm2
7 days 22.34 N/mm2
28 days 37.22 N/mm2

Fig.1 Chart showing the increase in strength with
the time of curing.
Fig.2 Casting of cubes.
Fig. 3 Testing of Cubes.
3.2 Scaling and casting of beams
A standard RCC beam of size 230mmx450mmhavinglength
2.5m is been considered from a residential plan and
designed using IS 456. Two different openings sizes of
100mm and 150mm are takenintoconsiderationatdifferent
locations along the length of the beam. Fe415 steel and M25
concrete are used. As casting curingandtransportingofsuch
beams is difficult, it is scaled down to a size which is easy for
practical purpose. Beam is scaled down to a size of 65mm
x126mm and having length 700mm. Similarly openings are
scaled down to a size of 28mm and 42mm respectively.
Initially 3 beams are casted and tested on the UTM
without any reinforcement in it having one, two, three
openings respectively on each beam of size 28mm so as to
identify the cracking pattern due towhichthebeamfails.Fig.
4 shows the formwork of the beams and placingofPVCpipes
so as to form the required openings. Fig. 5 shows the casting
and testing of the beam with 3 openings. The cracking
pattern of the beam can be seen in this figure.
Fig. 4 Formwork prepared on site.
Fig. 5 Casting and testing of beam with three opening.

3.3 Loading condition
The beam is placed over the jaws of the UTM and fixed over
it. The centre of the beam is marked and on equal distance
from the centre rolled steel sections are placed on each side.
Over these rolled steel sections a mild steel plate is placed
over which the central point load is applied bytheUTM.This
procedure is followed so as to apply a two point load as per
IS specification of applying a point load. Fig. 6 shows a
typical arrangement of the loading condition made.
Fig.6 Typical arrangement of two point loading condition.
4 Analytical approach
The beams will be modelled in the Finite Element Method
tool ANSYS and loading will be provided as shown above in
the two point form. The results will be noted and compared
to the experimental results. So as to taketheworstcasesinto
consideration the openings are kept at the centre of the
beam where the bending moment is maximum and at a
distance from support where the shear force is maximum.
List of models to be prepared are:
• Solid beam without hole.
• Beam with 100mm circular hole at L/2 distance.
• Beam with 150mm circular hole at L/2 distance.
• Beam with two 100mm circular holes at 175mm
from both ends.
• Beam with two 150mm circular holes at 175mm
from both ends.
• Beam with three 100mm circular holes at L/2
distance and other two at 175mm from both ends.
• Beam with three 150mm circular holes at L/2
distance and other two at 175mm from both ends.
5 Results
Sample models been prepared in ANSYS withone,two,three
openings along with the values of maximum deflection and
stresses are as shown below:
 Model of the beam without any opening
Results: Maximum Deflection: 0.00052314m
Maximum Stress: 3.7952e7 Pa
Maximum Strain: 0.00013948
 Model of beam having a single opening of size
100mm
 Model of beam having two opening of size 100mm

 Model of beam having three openings of size
100mm
80
100
120
0
20
40
60
80
100
120
140
0.00051 0.00052 0.00053 0.00054 0.00055 0.00056 0.00057
SIZEOFOPENING(m)
TOTAL DEFORMATION (m)
Graph showing total deformation vs. size of
opening.
6 Conclusion
 Deformation in beam without opening is less as
compared to beam with opening.
 Total deformation increases with the increase in
size of opening.
 Due to the openings total deformation, normal
stress, strainincreasethusadditional reinforcement
is to be provided and its design are need to be
recommended in IS codes.
 The crack pattern which the beam will undergo on
the action of practical loading condition or during
flexure test is obtained.
 Special reinforcement is to be designed to avoid the
inclined cracks undergone by the beam due to the
provision of openings in the beam during the test.
 After provision of designedreinforcementthebeam
is tested practically for flexure test and also models
of the same would be designed and tested
analytically in ANSYS so as to validate the obtained
results.
Acknowledgement
This work is synergeticproductofmanyminds. Iam
Grateful for the inspiration and wisdom of many thinkers
and for the trans-generational sources and the roots. I
hereby take this opportunity to express my profound
gratitude and deep regards to my guide Dr.Sanjay Kulkarni,
HOD, DYPSOET, to my co-guide Prof. Nikhil Landge, Miss.
Pranjali Kulkarni, Head of civil dept., DPCOE and staff of
material testing lab for their exemplary guidance,
monitoring and constant encouragement throughout the
course of this work.
7 References
Journal papers
1. Beams with Openings: and Design by Mansur, M.A. and
Kiang Hwee Tan.
2. Mansur, M.A., Tan, K.H. and Lee, S.L., "A Design Method for
Reinforced Concrete Beams withLarge Openings",Journal of
the American Concrete Institute, Proceedings, Vol. 82, No. 4,
USA, July/August 1985, pp. 517-524.
3. Reinforced concrete Beams with small opening inBending
and torsion by M.A.Mansoor and P. Paramasivam.
4. Somes, N.F. and Corley, W.G. (1974). Circular openings in
webs of continuous beams Shear in Reinforced Concrete,
special Publication SP-42, American Concrete Institute,
Detroit, 359-398.
Standard Codes
5. IS 456:2000.’Plain and Reinforced concrete-Code of
practice.’
6. IS 10262:2009 ‘Concrete Mix Proportioning’

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