Experimental Investigation on Behaviour of Reinforced ...
Transcript of Experimental Investigation on Behaviour of Reinforced ...
© 2020, WAJES All Rights Reserved 88
World Academics Journal of ___________________________________________ Research Paper . Engineering Sciences
Vol.7, Issue.2, pp.88-91, June (2020) E-ISSN: 2348-635X
Experimental Investigation on Behaviour of Reinforced Concrete Beam
Using Jute Fibre Reinforced Polymer Laminates
Udhaya Sankari S.P.1*
, Umamaheswari R.2
1Dept. of Civil Engineering, Anna University Regional Campus, Madurai, Tamil Nadu, India
2Dept. of Civil Engineering, University College of Engineering, Dindigul, Tamil Nadu, India
*Corresponding Author: [email protected]
Available online at: www.isroset.org
Received: 15/Apr/2020, Accepted: 19/May/2020, Online: 30/June/2020
Abstract— This experiment comes under rehabilitation work. Now a day’s retrofitting is expanding worldwide and it is
one of the best option to make an inadequate building safe against future probable earthquake or other environmental force.
Replacing the damaged structure is one of the difficult process as well as cost intensive process and also risky work
therefore retrofitting is one of the best solution .The purpose of this experiment is to study the behaviour of reinforced
concrete beam before and after retrofitting by jute fibre wrap and the bond between jute fibre and concrete is done with the
help of general purpose resin (GPR) to increase the strength of deteriorated beam by using M35 grade concrete. The result
says about the increase in its strength.
Keywords—Jutefibrewrap, Retrofiting, GPR, Rehabilitation
.
I. INTRODUCTION
The maintenance, rehabilitation and repair of structural
members is one of the major problems in civil engineering
applications. The structure constructed in the past using the
older design codes in different part of the world are
structurally unsafe according to the new design codes. The
replacement of such a structure needs huge amount of
money as well as time. Structures are also gets deteriorated
due to chemical attack, deficiencies of material, inadequate
design, development of cracks. Retrofitting by using JFRP
bonded externally with the help of general purpose resin
have been studied in this experiment work. Recent research
is being focused on usage of FRP in order to strengthen the
existing RC framed structural elements without disturbing
the existing the structural elements
Retrofitting with the help of FRP to strengthen as well as
for repairing damaged structure is a new technique.
researches are going in this area using FRP in the RC
structure to study about the structural performance in terms
of strength and ductility
A) OBJECTIVE
The main objective is to assess the feasibility of
strengthening reinforced concrete and to study the
contribution of externally bonded jute fibre reinforced
polymer in confinement of reinforced concrete beam. This
experiment is focused on the strengthening of beam which
are not able to withstand the shear resistance. Beam has
been strengthen which posses weak in shear .the failure
behaviour of beam and its ultimate load carrying capacity
of beam were observed
Reasons leading to retrofitting
The building which are designed under gravity load. Lack
of study on seismic zone. Improper planning and lack of
timely revisions of codes of practice and standards
Reasons for wrapping
It is light in weight, low cost, corrosion proof, easy to
install. The ratio of strength to weight FRP is more than
fifty times that of steel. It increases ductility and strength
of concrete beam. In the wrapping process it requires less
installation of time and also it does not change its original
features of structure
B) MATERIALS USED
Cement: Ordinary Portland Cement and Portland
Pozzolana Cement are the two most common types of
cement used in construction industries. It resist to dry
shrinkage and cracking. In this experiment we have used
OPC 53 grade cement .
Table 1.1: Cement properties
Properties Result
Initial setting time 30 minutes
Final setting time 10 hours
Fineness modulus 5%
Consistency 33%
Specific gravity 3.15
Fine aggregate: Fine aggregate consist of natural sand,
crushed stone sand and crushed gravel stone dust. It should
be passing through the IS 4.75mm size. For this study
river sand is used.
World Academics Journal of Engineering Sciences Vol.7, Issue.2, June 2020
© 2020, WAJES All Rights Reserved 89
Table 1.2: Sand properties
Properties Result
Grading of sand Zone II
Fineness modulus 5.34%
Specific gravity 2.67
Water absorption 0.8%
Coarse aggregate: Locally available crushed granite
coarse aggregates are used in this project, having the
maximum size of 10mm and it should be of hard, free from
dust, dirt and other foreign matters.
Table 1.3: Coarse aggregate properties
Properties Result
Specific gravity 2.88
Impact value 30.08%
Crushing value 40.71%
Water absorption 4.38%
Jute fibre: Jute is a natural fibre and it is easily available
at cheapest rate. It has high tensile strength and low
extensibility
Table 1.4: jute fibre properties
Properties Result
Tensile strength (MPa) 250
Elastic modulus(GPa) 1.6
Elongation at fracture(%) 22.7
Thickness(mm) 1.5
Stiffness(KN/mm) 2
GSM(gram per square meter) 260
Fig: 1.1 jute fibre sheet
General purpose resin (GPR): It is suitable for both hand
layup and gun spray up. It has good mechanical property,
impact and water resistance
Table 1.5: GPR properties
Properties Value
Density (g/cm3) 1.1
Specific gravity 1.13
Water: In this experimental work, potable water is used
for casting and curing of specimens. The pH value for the
water used should not be greater than 6.
II. LITERATURE REVIEW
Robert Ravi and Prince Arulraj (2010) they have done on
the experimental investigation on the control and
retrofitted beam column joints using CFRP and GFRP
hybrid wrapping and this paper concluded about the energy
absorption capacity of the beam column joints was found
to be 24.2% and it increases when compare with the
conventional specimen.
Balasubramanian et al (2007) in this paper they have
evaluated about the performance carbon and glass fibre
reinforced polymer wrapping used for retrofitting of the
beams and columns and ii concluded that the performance
was improved after retrofitting with the help of FRP
wrapping and it compare the both carbon and glass, they
provide almost similar performance. The RC columns
retrofitted with the single layer it posses good ductility
index , maximum strains.
Franceso Bencardino et al (2002) In this experiment they
have investigated about the strengthening of reinforced
concrete beam in flexure and shear with the help of
externally bonded bidirectional carbon fibre fabric to
overcome the bond slip and plate separation at the end.
This paper concluded that it provides an effective alternate
to laminates strengthening the existing structure
N.F. Grace et al(1999) this paper says about the using of
various types of FRP laminates in the structure. The carbon
and glass FRP have been used , it is externally bonded with
the beams with the help of epoxy resin and also this paper
says about the different layers of FRP sheet , types of
epoxy as well as its strengthening pattern. In this paper
they have concluded by calculating its absorbed energy to
total energy and behaviour of strengthening of beams are
exhibits in higher factor of safety in design
III. EXPERIMENTAL PROGRAMME
The beams were casted by M30 grade concrete and Fe 450
steel with the guidelines of code book IS 10262:2019. The
beams were wrapped with the JFRP where its thickness is
1.5mm and bonded externally with the help of general
purpose resin. In this study the retrofitted beam is
compared with the conventional beam. Before wrapping
the beam the initial load is given, that is the load is given
till the initial crack is appear then it is released from the
load and general purpose resin is applied on the beam and
JFRP is wrapped and then it is allowed for sun dried for 7
days after that the wrapped beam is tested.
A) CASTING OF BEAM
The beams are casted as per the design consideration
which includes conventional as well as beam need for
retrofitting. All the beams are casted according to the mix
design after that quantity of the material is calculated as
per the dimension of the beam, the volume of the beam is
0.024m3. After weighting the materials as per the quantity
all the coarse aggregate, fine aggregate, cement has to
World Academics Journal of Engineering Sciences Vol.7, Issue.2, June 2020
© 2020, WAJES All Rights Reserved 90
mixed by adding required water after providing steel
reinforcement.
After placing the reinforcement cage into the beam mould
the concrete mix has to be poured into the mould in the
forms of layers. After filling first two layers it has to be
vibrate so that the air voids can be avoided and after filling
the next layer also we have to vibrate. At last level the top
surface by using trowel. The beams are removed from the
mould after 24 hrs and curing is done for 28 days
Fig: 3.1(a) casting
B) PROCESS OF WRAPPING JFRP
The first step is to clean the surface of the specimen
completely with the help of brush and JFRP is cut as per
the dimension of the specimen for each beam the sheet
dimension is 400X1600 mm and the pattern used for
wrapping is U pattern. In the wrapping pattern there are
various types of patterns are there such as U shape, V
shape, and I shape among them U pattern is recommended
since it helps to resist the load when compare with the
other type pattern. Finally the general purpose resin is
applied thoroughly in the bean immediately the JFRP is
wrapped and then allowed to sun dry.
Fig: 3.2(b) wrapping and dry
C) TESTING PROCEDURE The retrofitted beams and the conventional beams were
tested under two point bending load in order to know the
ultimate bearing capacity. The two supports were
considered as simply supported condition then I sectional
girder beam was placed to apply the two point loading on
the beam the loading was applied to the centre of the
specimen and transmitted to two points loading until
failure and note down the corresponding deflection from
the dial gauge.
Fig: 3.3(c) 1. Conventional beam
Fig: 3.3(c) 2. Retrofitting first the bean is allowed to obtain initial
crack
Fig: 3.3(c) 3. Wrapped beam is tested
World Academics Journal of Engineering Sciences Vol.7, Issue.2, June 2020
© 2020, WAJES All Rights Reserved 91
IV. RESULTS AND DISCUSSION
Two sets of beams were tested under the loading condition
and the beams are in simply supported condition and
finally the comparison of conventional and retrofitted
specimens were analyzed from the result.
A) FOR CONVENTIAL BEAM The test result for the convention beam are
Table 4.1: Test result
Compressive strength 36.4 KN/m2
Split tensile strength 2.41 KN/m2
Flextural strength 5.25 KN/m2
0
1
2
3
4
5
6
7
8
9
10
5 10 15 20 25 30 35 40 42
load (KN)
de
fle
ctio
n (
cm)
A
B) FOR WRAPPING SPECIMEN
i) In this first the beam is given load till it obtain the initial
crack and its graph between deflection vs load are
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2 4 6 8 10 12 14
load (KN)
de
fle
ctio
n (
cm)
A
ii) After the beam is given initial load , the beam is
wrapped with JFRP bonded with GPR (general purpose
resin). Then the beam is kept for sundry after its
completely dry the specimen is tested and its graph
between deflection vs load are
0
1
2
3
4
5
6
7
8
9
10
4 8 12 16 20 24 28 32 36 40 44 48
load (KN)d
efl
ect
ion
(cm
)
A
V. CONCLUSION
From the result we can conclude that
I) comparing both the conventional and wrapped specimen
we can say that the strength of the wrapped beam is
increased by 47.6% when comparing with the conventional
beam.
II) It is more economical when compare to other FRP.
III) The serviceability of the structure gets increased.
REFERENCES
[1]. Uji k. “Increasing the shear capacity of existing reinforced
concrete structure members by applying with the help of carbon
fibre sheetsˮ. Transaction of the japan concrete institution,volume
14. 1992
[2]. Miyachui K. “increasing the strength of concrete column with the
help of carbon fibre sheetˮ. Transactions of the japan concrete
institute, volume 21, 1999.
[3]. Raju A. and Matew L.A. “ Retrofitting of RC Beam using FRPˮ.
International journal of engineering research and technology
(IJRET), 2(1),2013,PP.6-10.
[4]. Hamid R. and Allan H. “concrete beams externally bonded with
FRP platesˮ. journal of composite for construction , ASCE, 1(5),
2001,PP.45-56.
[5]. Rohit V and Manideep K. “ Retrofitting of RC beams using glass
fibre reinforced polymer sheetsˮ. Indian journal of science and
technology (IJST), 9(44),2016, pp.1-11.