International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 864–870, Article ID: IJCIET_10_04_091
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJCIET&VType=10&IType=4
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
Scopus Indexed
COMPARATIVE STUDY OF BEAMS BY USING
DIFFERENT TYPES OF RETROFITING
TECHNIQUES
Mansi Saini
Scholar, Department of Civil Engineering, Chandigarh University, Mohali, India
Aditya Tiwary
Assistant Professor, Department of Civil Engineering, Chandigarh University, Mohali, India
ABSTRACT
The main aim of this study was to increase the strength of beams by using different
types of jacketing techniques and checks the most cost-efficient methods. In this paper,
the reinforced concrete (RC) jacketing and carbon fiber reinforced polymer jacketing
was used for retrofitting the beams. In this research study, 100 mm thickness of RC
jacketing is used in all four sides of beam and carbon fiber reinforced polymer
(CFRP) of different thickness of sheet are used. The point load test is done on loading
frame machine and check the crack, ultimate strength and comparing the results and
cost of all different types of retrofit techniques for reinforced concrete. Analyses was
also performed on ABAQUS software and then validation is done by comparing the
deformation and stress behavior in ABAQUS and experimentally. It was observed that
the RC jacketing strength increased 63% and 48.5% strength increase in CFRP. The
test results show that the RC jacketing gain more strength then other jacketing
methods and increase the flexural strength.
Key words: Beam, RC jacketing, CFRP jacketing.
Cite this Article: Mansi Saini and Aditya Tiwary, Comparative Study of Beams by
Using Different Types of Retrofiting Techniques, International Journal of Civil
Engineering and Technology 10(4), 2019, pp. 864–870.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=4
1. INTRODUCTION
Although reinforced concrete structures have high strength but due to earthquake and other
effects like wind load, seismic load and creep, the structure get fails, deteriorates, losses its
strength over time [1]. As the structure reaches its service life the load carrying capacity of
structure also decreases. So, the structure gets retrofitted by using different methods of
jacketing. It may necessary to combine both local and global retrofit strategies under feasible
& economical retrofit scheme.
http://www.iaeme.com/IJCIET/index.asp
864
editor@iaeme.com
Comparative Study of Beams by Using Different Types of Retrofiting Techniques
1.1. Global Strategies
When a building facieses several deficient and damage due to earthquake, wind & lateral load
effect it is necessary to provide strength & lateral load resisting element so addition of infill
walls, shear walls, bracing increases the strength.
Local Strategies Local strategies are done in beam, column, beam column joints in local
strategies retrofit are done by jacketing that is steel, concrete or FRP and then comparisons
are done to check which are more suitable for multi-story building.
2. MATERIALS AND METHODS
Cement
An ordinary Portland cement (OPC) of grade 43 was used for the construction work with
specific gravity 3.15. The bulk density of cement is 29.48 kg/m3.
Sand
Crushed sand was used with specific gravity 2.64, here crushed sand used for the good
bonding strength. The bulk density is 1493.56 kg/m3 and the water absorption is 1%.
Coarse aggregate
The maximum size of aggregate of 10 mm having specific gravity 2.62 was used and grading
of aggregate was zone II. The bulk density is 1476 kg/m3 and the water absorption is 6%.
Carbon fibre
CFRP is having high strength, durability. It is used for high strength and rigidity of different
thickness and numbers of layers used for retrofitting of beam.
Epoxy resin
Epoxy resin was used for good bonding between concrete surface and carbon fibre sheet.
2.1. Experimental Programme
RC beam have been casted and tested under different loading condition. Four beams were
casted of size 230×230×1500 mm3, the span length of beam is 1500 mm and width are 230
mm. In this the beam are design by using limit state method and the concrete grade of M40.
The quantity of materials is calculated by using the code that is mix design specification BIS
10262:2009. The size of reinforcement is 4 no’s 12 mm diameter bar used in both
compression and tension member and grade was Fe 415. The stirrups size is 6 No’s with 8
mm diameter of 250 mm centre to centre spacing [2]. The load applied at centre as shown in
Figure 1. Before beam, two cubes were casted and tested for check the compressive and
tensile strength that is 39.5 N/mm2, 5 N/mm2.
Figure 1 Point load on beam
http://www.iaeme.com/IJCIET/index.asp
865
editor@iaeme.com
Mansi Saini and Aditya Tiwary
2.2. Casting of RC beams
The beams were cast. The size of all specimens was identical and shape was square having
dimensions 230×230×1500 mm3. The rectangular wooden mould was prepared as shown in
Figure 2 and rectangular reinforcement cage also performed as shown in Figure 2. The mixing
of concrete was done by using mix design specification BIS 10262:2009, after mixing beams
were casted by proper alignment of reinforcement of size main bar was used 12 mm and shear
reinforcement was 8 mm with 250 mm centre to centre spacing. The casted of beams were
shown in Figure 3. After casting of beams, the first point load was applied on beam to check
the crack load and ultimate load of all control beams. After testing, the all control beams were
retrofitted by using RC jacketing, CFRP jacketing. CFRP used to increase the strength and its
also helps to protect the beam from corrosion [3,4]
Figure 2 Plywood moulds with Reinforcement cage
Figure 3 casting of beams
2.3. Retrofitting of beams
2.3.1. RC jacketing’s.
All four sides of beam were retrofit by using RC jacketing. The 100 mm jacketing used in all
four sides of beams with reinforcement size 4 No’s of 16 mm diameter bars and shear
reinforcement size 6 no’s 8 mm diameter bar 280 mm center to center spacing. The size of
beam become 430×430×1700 mm3, the span length became 1700 mm and cross section area
became 430×430 mm2 and concrete grade M45 and steel grade 415 was used. Retrofitting of
beam shown in Figure 4.
Figure 4 Retrofitting of beam
Figure 5 Recasting of beam
2.3.2. Carbon Fiber reinforced polymer
The beam was wrapped with all four sides by CFRP sheets of different thickness that is 0.3
mm [5]. Before providing the CFRP sheet on all sides of beam first made the surface rough
and clean by using wire brush and then mixing the epoxy resin properly in any container.
After mixing, apply the epoxy primer on beam by using brush for a good bond between the
concrete surface and CFRP sheet and the wrap the beam by using CFRP sheet of thickness 0.3
http://www.iaeme.com/IJCIET/index.asp
866
editor@iaeme.com
Comparative Study of Beams by Using Different Types of Retrofiting Techniques
mm with single layer or also unidirectional [6,7] and then check it for strength. The
retrofitting of beam was kept under room temperature and work also done on room
temperature for protecting the moisture. The retrofitted beam cured for 3 days under room
temperature.
3. TEST AND RESULTS
3.1. Testing of beams
All beams were tested under loading frame machine for the flexural strength. four beams were
casted, all beams tested under point load by using loading machine. After testing the crack
pattern and crack load were checked and also checked the ultimate load.
Figure 6 Experiment test set up and point loading arrangment
Figure 7 Control beam with crack and failure pattern
Table 1 Deflection of control beams at crack load and ultimate load
Sr. No.
B1
B2
B3
B4
Crack point
Crack load (kN) Deflection (mm)
61
7.4
60
6.3
61
7.4
55
4.0
Ultimate point
Ultimate load (kN) Deflection (mm)
110
13.2
107
11
110
13.2
105
10.8
Table 2 Deflection of retrofitted beams at crack load and ultimate load
Sr. No.
B1 (RC jacketing)
B2, B3 (CFRP-0.3MM)
B4 (CFRP-0.4MM)
Crack load (kN)
142
120
125
http://www.iaeme.com/IJCIET/index.asp
Deflection
(mm)
19.5
17.3
17.8
867
Ultimate load
(kN)
180
150
156
Deflection
(mm)
21.4
19.7
19.9
editor@iaeme.com
Mansi Saini and Aditya Tiwary
Then beam was retrofitted and tested again. The specimen B1 retrofitted by using RC
jacketing and then strength was checked by applying point load on particular surface also
check the stress and displacement of all beam that is control beam and all retrofitted beams.
When load was applied first crack load was checked and deflection of beam and then checked
the ultimate load. The specimen B3 and B4 retrofitted by CFRP sheets of thickness 0.3 mm
and 0.4 mm with single layer and then load was applied and check the strength. After
applying the jacketing on all beams, comparing the results with control beam and retrofitted
beams which was retrofit by different techniques and then check which was most suitable and
cost effected methods and also check the strength also the behavior of load deflection of all
beams was compared. The deflection graph was plotted. The RC jacketed beam has more
strength as compared to control and other retrofitted beams and less in cost also.
It has been found that the crack load of beams without retrofit is between 60 kN to 62 kN
and ultimate load between 120 kN. The control beam has maximum deflection and less
ultimate load carrying capacity and shear capacity. The crack load of RC jacketed is beam
120 kN to 140 kN and ultimate load between 180 kN to 200 kN. In CFRP jacketing with
single layer of sheet the first crack load appeared at 110 kN.
3.2. Software analysis
The RC beam design in software ABAQUS with dimension 230×230×1500 mm3. First the
different -2 part were prepared and then assign the properties of concrete and steel and then
assemble the all parts to make it RCC beam as shown in fig. The interaction part is done to
make the structure interact with each other so it shows deformation properly and define the
penalty friction coefficient 0.8 in tangential behavior. The simply supported support was
assign by using boundary condition and applied load crack and ultimate load to check
deflection and then compare the result with experimental work. The important part was
meshing which means that it checks every part of nodes.
Field output and history output are done in job analysis part and the step increment is the
most important which is decided by the load. Then creating a job for analysis, the result.
Table 3 Deflection of control beams at crack load and ultimate load in software
Sr. No.
B1
B2
B3
B4
Crack point
Crack load (kN) Deflection (mm)
61
5.78
60
5.13
61
5.78
55
3.15
Ultimate point
Ultimate load (kN) Deflection (mm)
110
11.05
107
9.35
110
11.05
105
9.18
Table 4 Deflection of retrofitted beams at crack load and ultimate load
Sr. No.
Crack load (kN) Deflection (mm) Ultimate load (kN) Deflection (mm)
B1(RC jacketing)
142
16.6
180
18.2
B2, B3(CFRP-0.3MM)
120
14.7
150
16.7
B4(0.4mm)
125
15.1
156
16.9
http://www.iaeme.com/IJCIET/index.asp
868
editor@iaeme.com
Comparative Study of Beams by Using Different Types of Retrofiting Techniques
Figure 8 Deformation and stress in control beam
3.3. Validation
In this it shows that during the experimental work the maximum deflection and bending occur
at center of beam and also in analytical work.
Figure 9 Deformation in control beam
Figure 10 deflection of control beams (Series 1 software results and series 2 experimental
http://www.iaeme.com/IJCIET/index.asp
869
editor@iaeme.com
Mansi Saini and Aditya Tiwary
4. CONCLUSIONS
The flexural behavior of reinforced concrete beams strengthens by RC, Steel, CFRP sheets
having different thickness are studied and investigated and following conclusion were made:
1. Due to strengthen by RC, CFRP, ultimate strength and bearing capacity of beams
increased.
2.The average crack load of control beam and retrofitted by RC was found 60 kN to 61 kN
and 140 kN ultimate load of control beam but the crack load of retrofitting beams found
between 120 kN and ultimate load 200 kN
3. The ultimate strength of RC jacketing increase 63% more than the control beam and other
jacket beam.
4. The ultimate strength of CFRP jacketing increase 48.5%more than the control beam. It was
found that CFRP is also good for corrosion resistance.
5. All four sides jacketing of beams has more strength and bearing capacity. It increases the
capacity of resistance as the demand of load increase.
6. These all methods help for future to retrofitting the structure either beam, column or also
define the crack pattern, depth and failure load.
7. The cost of RC jacketing is less than steel and CFRP, the CFRP has large cost as compared
to steel and RC. So, RC jacketing is good in both strength and cost.
REFERENCES
[1]
Bhavar Dadasahebet. al. “studied the structural behavior of RCC building” IRJET journal
(2013).
[2]
S.P. Tastani, “establishes the confinement model”. Construction and building material
(2013).
[3]
AhmedKhalifa et.al “Improve shear capacity of existing RC beams using CFRP
composites. Cement and concrete Elsevier science (2000)
[4]
Tastani et al (2006), “recovery of seismic resistance in corrosion-damaged reinforced
concrete through FRP jacketing” Canadian journal of civil engineering.
[5]
Nalivenkatakrishna et.al “study the behavior of reinforced concrete beams using
externally bonded CFRP”. Journal of emerging technologies and innovative.
[6]
Dr P. Sivakumar “investigate the behavior of concrete beams by using CFRP
unidirectional laminates under loading” international conference on emerging technology
trends”
[7]
Michale et al “the behavior of concrete confined with reinforced polymers (FRPs)” journal
of composites for construction (2005).
[8]
Abhishekjodwat “Improving shear capacity of existing RC beams using external bonding
of steel plates", Engineering Structures, (2016), 27, 781-791.
http://www.iaeme.com/IJCIET/index.asp
870
editor@iaeme.com