Structural Health Monitoring and Strengthening Of BridgesStructural Health Monitoring and Strengthening Of Bridges

International Journal of Science and Engineering Applications
Volume 4 Issue 5, 2015, ISSN-2319-7560 (Online)
www.ijsea.com 309
Structural Health Monitoring and Strengthening Of
Bridges
Shridhar K. Panigrahi
Department of Civil
Engineering
MGM’s College of Engineering
and Technology
Navi Mumbai, Maharashtra,
India
P.J.Salunke
Department of Civil
Engineering
and Technology
India
N.G. Gore
Department of Civil
Engineering
and Technology
India
Abstract: This paper presents one bridge which were either rehabilitated or strengthened by using FRP composites. The resulting
structure was then tested for the effect after using FRP composites for Rehabilitation and strengthening. In this paper, Structural
Health Monitoring basics are covered and need for SHM in future in or India scenario. Use of FRP composites in Rehabilitation
and Strengthening of structures is becoming increasingly popular and is opening new possibilities in construction and rehabilitation
of structures.
Keywords : Rehabilitation, Structural Health Monitoring, Bridge Strengthening, Repair
1. INTRODUCTION
In the recent years, rapid deterioration of exiting
bridge structures has become a serious technical and
economical problem in many countries, including highly
developed ones. Therefore, bridge rehabilitation is one of the
most important tasks in civil engineering. Bridge rehabilitation
process should be preceded by assessment and evaluation of the
structure to determine its actual technical condition and to select
the proper rehabilitation techniques and materials. The reasons
leading to deterioration of the existing bridge are more or less
same in every country.
a) Increase in traffic flows and weight of vehicles, especially
their axle loads, compared to the period when the bridges
have been designed and constructed.
b) Harmful influence of environmental pollution, especially
atmospheric ones, on the performance of structural
materials,
c) Low quality structural material as well as bridge
equipment elements, such as expansion joint,
waterproofing etc.
2. SCOPE OF WORK
The focus of this present work is to study the
effectiveness of the bridge rehabilitation with respect to
different aspect such as strain measurement, vibration
measurement, deflection measurement, temperature
measurement etc. The project contains one case study which are
as follows.
Rehabilitation and Testing of Karal Rail Over
Bridge at JNPT, Navi Mumbai
3. AIMS AND OBJECTIVES
The aims and objectives of “Rehabilitation and
structural health monitoring of bridge superstructure”
dissertation are as follows:
1) To study strengthening techniques of bridge rehabilitation.
2) To study the effectiveness of the FRP material and external
pre-stressing in the field of bridge rehabilitation.

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3) To study the different type of damages in concrete
structure.
4) To study the behavior of the bridge before and after
strengthening.
5) To develop a 24 x 7 bridge monitoring system for
deflection, vibration and strain measurements for
vehicular loading.
4. CASE STUDY
Port at Nhava-Sheva, Navi Mumbai is managed by
Jawaharlal Nehru Port Trust (JNPT). This port is one of the
busiest port and handles about 70% of container traffic of whole
INDIA has constructed Rail over bridge at Karal for efficient
traffic flow. The construction of this bridge was completed and
opened for traffic since 1991. This bridge consists of 36 spans
of varying lengths with 37 expansion joints. The total length of
bridge is 700 m.
Upon critical inspection and the comparison of the
design load versus the strength of the girders of the Karal ROB,
it was observed that
1. The girders provided in the bridge are not adequate to
resist the design vehicle load as per revised IRC
recommendation,
2. occurrence of the structural cracks in the girders (i.e.
vertical crack in the centre and diagonal cracks at the end)
which prove the structural inadequacy of the girders and
3. Presence of visible sag in the superstructure, it
confirms that the superstructure may not be quite adequate to
resist the increased vehicular traffic load on the Karal ROB in
recent years.
5. SCHEME FOR STRENGTHENING
THE BRIDGE
1. The girders and slab of the bridge have been strengthened
by placing the additional steel truss system along the two main
girders in each lane (i.e. along the girder 2, 3, 6 and 7 are to be
placed in each span of and 1, 4, 5 and 8 remain as it is). The
truss system is supported by bridge deck/slab and cross girders
using the M32 high strength bolts. This truss system is
designed to take about 50% of the load carrying capacity of
the existing girders. [8, 10,12,13,14-20]
Connection of truss over main beam
Pre-stressing Mechanism in Truss
2. The bearings provided in the bridge between girders and
piers were damaged and were insufficient to take the increased
load. Elastomeric bearings have thickness around 75mm and it
become 25mm because of heavy traffic load. It is suggested to
replace all the existing neoprene/elastomeric bearings with the
new elastomeric bearings as shown in Figure 6.4.
Replacement of damaged Bearings with new
3. It is also recommended to replace the expansion
joints of the bridge with the Wabocrete Strip Seal Expansion
Joint System.

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4. It is recommended to strengthen the RCC girder
beams with FRP Carbon laminates.
5. In order to further improve the structural strength of
the bridge, it is recommended that the fiber reinforced plastic
composites wrapping around the girder.
6. To check the strength of FRP wrapping and steel truss
different types of measurements have been taken before and
after the strengthening.
Groove for carbon Fibre composites laminates
Carbon fibre wrapping
6. TEST SCHEME AND
INSTRUMENTATION
The various measurements to ascertain strengthening
effect has been presented below.
1. Measurement of strain, deflection and vibration of three
spans of the Rail Over Bridge of JNPT at the identified
locations under the static and rolling load before
rehabilitation/retrofitting.
2. Measurement of strain, deflection and vibration of the
three spans of the Rail Over Bridge of JNPT at the same
identified locations under the same static and rolling load
after retrofitting.
Besides this, to estimate condition of concrete in
existing structure, Rebound hammer tests and Ultrasonic Pulse
Velocity (UPV) tests were also proposed before strengthening.
7. NDT ON SUPERSTRUCTURE
1) Testing of Bridge girder using UPV (Ultrasonic
Pulse velocity) test to obtain quality of concrete. All
the girders will be tested at minimum 3 locations on
each under direct transmission. (Figure 6.6 (a))
2) Testing of Bridge girder using Rebound hammer to
estimate the characteristic strength of the girder. All
the girders have been tested at minimum 12 locations
(6 locations on each face of the girder.(Figure 6.6 (b))
.
Table 1
Rebound Hammer Test Results of RCC Girder
Beams
(DIGI Schmidt 2000 Rebound Hammer)
Sr. no Location
Avg. fck
in MPa
Bay 1
1 Girder Beam 1 59.5
[13,10,12]
Table 2
Result of Ultrasonic Pulse Velocity
Measurements of RCC Girder Beams
Sr. No. Location
Pulse
Velocity in
Km/Sec
Concrete
Quality
1 Girder Beam 1 3.57 Good
[13,10,12]

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Table 3
Average Central Deflection (mm)
Span-1 Span 2
Before
strengthening
5.38 mm 5.18 mm
After
strengthening
3.93 mm 3.65 mm
Reduction in
defection
1.46 mm 1.53 mm
% reduction in
deflection
-27.10% -29.50%
[2, 13, 10]
Table 4
Average Flexural Strain (µε)
Span 1 Span 2
Before strengthening 450 µε 407 µε
After strengthening 198 µε 188 µε
Reduction in Flexural
Strain
262 µε 219 µε
% Reduction in
Flexural Strain
-58.20% -53.80%
[2,5,13,10]
Table 5
Crack Width of Diagonal Cracks near Support
(Change in change width over a gauge
length of 200mm in µε)
Span 1 Span 2
Before strengthening 80 µε 90 µε
After strengthening 42 µε 28 µε
Reduction in Shear
Strain
38 µε 52 µε
% Reduction in
Shear Strain
47.5 (%) 57.8 (%)
[2, 5, 13, 10]
Table 6
Average Acceleration (mm/s2
)
Span 1 Span 2
Before
strengthening
21.38 mm/s2 35.91
mm/s2
After strengthening 11.43 mm/s2 15.93
mm/s2
Reduction in
Acceleration
9.95 mm/s2 19.98
mm/s2
% Reduction in
Acceleration
46.5 (%) 55.6 (%)
[2,3,7,5,13,10}
8. CONCLUSIONS
1. Central defections obtained under standard loads
indicate significant improvement in the flexural stiffness of the
RCC girder beams after rehabilitation and effectiveness of the
pre-stressed steel truss straitening system. Reduction in
deflection of all the two spans indicates that the flexural
strengthening system (FRP laminate and Pre-stressed steel truss
system) is effective in sharing the vehicular loads. An average
of 26% reduction in the deflection of bridge superstructure
under standard loads has been observed.
2. Flexural strains measured under standard loads
indicate significant improvement in the flexural stiffness of the
RCC girder beams after rehabilitation and effectiveness of the
pre-stressed steel truss straitening system. Reduction in flexural
strain of all the three spans indicates that the flexural
strengthening system (FRP laminate and Pre-stressed steel truss
system) is effective in sharing the vehicular loads. An average
of 53% reduction in the flexural strain in RCC girder beams
under standard loads has been observed.
3. Change in the width of the diagonal shear cracks on
the RCC girder beams near the support have been measured
before and after strengthening with the help of omega type
strain gage based transducer. An average of 56.8% reduction in
the shear strain in RCC girder beams under standard loads has
been observed. Reduction in the shear strain after rehabilitation
indicates significant enhancement in the shear stiffness as a
result of FRP wrap and Steel truss system.

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4. Reduction in the vibration of the superstructure was
envisaged due to rehabilitation of RCC girder beams and
strengthening with steel truss system. An average reduction of
8.5% in fundamental frequency of vibration is achieved. In
addition to this, the amplitude of acceleration has been reduced
by 50%. The increase in fundamental frequency of vibration
and reduction in amplitude of acceleration indicate that the
significant improvement in the overall stiffness of the structure.
9. REFERENCES
1. Branko Glisic and Daniele Inaudi, “ Fibre optic met
hods for structural health monitoring”, John Wiley &
Sons, Chichester, 2007.
2. Guidelines for Structural Health Monitoring, ISIS
Canada.
3. International Society of Structural health Monitoring
and Intelligent Infrastructure, www.ishmii.org
4. “Report on Dam Safety Procedures”, Government
Of India, Ministry of Water Resources.
5. Jacob Egede Anderson, “Structural Health
Monitoring Systems”, Cowi A/S and Futurtec OY,
2006.
6. “Report card for America’s Infrastructure”,
American Society of Structural Engineers, 2005.
7. http://memory.loc.gov/ammem/collections/habs_ha
er/ Radomski W., Bridge Rehabilitation, Imperial
College Press
8. ACI Committee 440. State-of-the-Art Report on
FRP for Concrete Structures. ACI 440R-96
9. Manual of Concrete Practice, ACI, Farmington
Hills, MI, 1996, 68 pp.
10. G.L. Rai, “Different Strengthening Techniques for
RC Columns”, R&M International.
11. B.N. Pandya, M. M. Murudi, A. A. Bage, “Seismic
retrofitting of reinforced concrete
buildings”,Proceedings WSRR 09.
12. Gopal Rai, Kulvinder Singh, Yogesh Singh,
“External Pre-Stressing Using Carbon Fiber
Laminates”,Proceedings WSRR09, IIT
Bombay
13. Bambole A. N., Jangid R. S., Rai G. L.,
“Rehabilitation and Testing of the Karal Rail Over
Bridge for JNPT, Navi Mumbai” , Proceedings
WSRR09, IIT Bombay
14. ACI 440-2R
15. IS 15988:2013
16. IS 800: 2007
17. FIB-14
18. IS 456:2000
19. IS 13311 (Part- I): 1992
20. IS: 1331 (Part 2): 1992
Personal Details of Main author
Name: Shridhar Panigrahi
Education : M.E. Structure Pursuing
Address: M.E.S Quarter (P-163/8)
Road Post Sandoz Baug
A.F.S Thane(West)
Mobile : 9967621053
Email-ID : kpshridhar18@gmail.com
College Name: MGM’s College of Engineering &
Technology

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