PROJECT ASSOCIATE WORK REPORT

From 19-06-2024 To 30-09-2024

By

KAVITHAYINI. R
(Project Associate – II)
STRUCTURAL HEALTH MONITORING LABORATORY

CSIR – Structural Engineering Research Centre

(Council of Scientific & Industrial Research)
CSIR Campus, Taramani, CHENNAI – 600113
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ACKNOWLEDGEMENT

I would first and foremost like to thank Dr. Anandavalli, Director, CSIR – Structural
Engineering Research Centre, Chennai, for giving me an opportunity to work with scientists
at CSIR – SERC.

I would like to express my gratitude to Dr. V. Srinivas, Chief Scientist and Head, SHML and
Dr. B. Arun Sundaram, Principal Scientist, SHML for their valuable suggestions and
encouragement during the work period.

I am grateful to staff members of SHML and my friends for their support in all aspects during
my stay at CSIR – SERC.

Kavithayini.R
(Project Associate - II)

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ABOUT INSTITUTION

CSIR-Structural Engineering Research Centre, established in 1965 and located in

Chennai, has been making significant contributions through research and development in the
area of structural engineering.

CSIR-SERC over the five decades of its existence has undertaken all the activities and
has excelled in most of its pursuits. It has provided high quality R&D and S&T to the
industry. There have been, any land mark achievements, and many laurels to its credit.
Presently India is expanding its infrastructure very fast and consequently the demands of
contribution by CSIR-SERC have increased manifold. CSIR-SERC has identified a number
of thrust areas for in-house R&D and has created excellent infrastructure for the same
through generous government grants, UNDP assistance, and External Cash Flow (ECF)
realized through its own activities. All the facilities created are of world class are being
continually updated to keep them as state-of-the-art facilities.

The major infrastructure at CSIR-SERC is as follows

i. Steel Structures Laboratory

ii. Structural Health Monitoring Laboratory
iii. Special & Multifunctional Structures Laboratory
iv. Advanced Seismic Testing and Research Laboratory
v. Advanced Protective Structures and Mechanics Laboratory
vi. Tower Testing and Research Station
vii. Fatigue & Fracture Laboratory
viii. Wind Engineering Laboratory
ix. Advanced Concrete Testing & Evaluation Laboratory
x. Advanced Materials Laboratory

Structural Health Monitoring Laboratory

Structural Health Monitoring plays an important role in the design and performance
assessment of structures and structural components, in particular, in critical application areas
where safety and integrity are of paramount importance. SHML seeks to develop innovative
methodologies and strategies for increasing the safety and reliability of civil engineering
structures. Our research is focused on the areas of structural health monitoring, performance

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evaluation of civil infra structures, development of methodologies for pipeline monitoring

and vibration based assessment of structures. One of the major activities of the laboratory is
to apply the techniques and expertise to solve industrial problems. Our lab has carried out
several consultancy/sponsored research projects for many organizations from Government,
public and private sectors. The Lab continuously strives to be a focal point for structural
health monitoring of civil engineering structures in India. The Major Facilities in the
Laboratory are
Data Acquisition systems for measuring structural responses:
 Data acquisition systems for electrical resistance strain gauges up to 300 channel
capacity (Static testing)
 Data Acquisition Systems for Dynamic response measurements up to 160 channel
capacity (Displacement transducers, accelerometers and strain gauges )
 Data loggers for EFPI and FBG fiber optic sensors
 Data acquisition systems for vibrating wire sensors up to 60 channel capacity

Other Facilities
 Total station, Tilt and Inclinometer systems for Structural monitoring
 Equipments for In-situ Stress Measurements in Concrete/Masonry Structures
 Blind-hole drilling equipment and Magnetoelasticity for residual stress measurement
 Load cells, displacement transducers, recorders, etc
 Strain gauges & FBG, Fiber Optic Sensors
 Laser based Displacement measurement systems
 Accelerometers

WORK DONE:

PROJECT TITLE: Design adequacy check of selected railway bridges

executed as part of the Vanchi Maniyachi Juction – Nagercoil Junction
doubling work of Southern Railway (SSP- 389)

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1. Experimental investigations of the New Pamban Railway Bridge at Rameshwaram

during the load test

SUMMARY OF WORK DONE

Rail Vikas Nigam Limited (RVNL) is carrying out the construction of the New Pamban
Railway bridge at Rameshwaram connecting the Indian Mainland with the Pamban island.
The construction of the new bridge is nearing completion. In this connection, RVNL
approached CSIR Structural Engineering Research Centre (CSIR SERC) for carrying out the
instrumentation and response measurement during the load testing of the New Pamban
Bridge. The bridge consists of 99 approach spans and one navigational lift span. It was
proposed to carry out the experimental investigations in four approach spans and the lift span.
During July 2024, experimental investigations have been completed in some approach spans
– Span 42 and Span 100 (Figs 1 and 2). The instrumentation carried out and the responses
measured during the experimental investigations is presented below.

Fig. 1 General View of Pamban Bridge

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Fig. 2 General View of Span 42

Fig. 3 Typical Arrangement of LVDT

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TESTING SEQUENCE
Both static as well as dynamic tests were conducted using the test train. The different tests
conducted is presented in Table 1.

Table 1 Sequence of tests conducted at bridge site

Sl.No. Test case Details

STATIC TESTS

1. Test-1 Loco 2nd Axle placed at Midspan

2. Test-2 Loco 1st Axle placed 1m from MMM Support
3. Test-3 Wagon 2 First Axle 1m from MMM support
4. Test-4 Wagon 2 and Wagon 3 Coupler at Midspan
5. Test-5 2nd Wagon 4th axle at Midspan
DYNAMIC TESTS

6. Test-6 Train running with uniform speed of 8 kmph from MMM to PBM

7. Test-7 Train running with uniform speed of 20 kmph from PBM to MMM

8. Test-8 Train running with uniform speed of 40 kmph from PBM to MMM

RESULTS
The load testing was carried out using a standard test train formation. The responses recorded
under the standard axle loads have been extrapolated to the design loads as per the bridge
rules. From the table 2 and 3, it can be seen that a maximum deflection of 15.03 mm is
obtained for span 42 and 20.31 mm is obtained for span 100. The maximum measured
deflections for all load cases is shown in Fig.4 and Fig 5.

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Fig. 4 Measured Deflections for each Load Cases of span 42

Span (m)
0 2 4 6 8 10 12 14 16 18 20
0
1
2
3
Deflaction (mm)

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5
6
7
8
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10
IG-18 kmph OG-18 kmph IG-20 kmph OG-20 kmph
IG-40 kmph OG-40 kmph IG-54 kmph OG-54 kmph

Fig. 5 Measured Deflections for each Load Cases of span 100

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Table 2 Vertical displacement for design loads extrapolated from span 42 load test

Deflection (mm)
case 1 case 2 case 3 case 4 case 5
OF VER OG -16.84 -12.98 -12.38 -13.59 -13.95
MID VER OG -22.04 -14.61 -15.73 -17.14 -17.30
TF VER OG -14.93 -10.46 -11.11 -11.90 -11.90
OF VER IG -13.34 -10.85 -10.71 -11.70 -11.90
MID VER IG -20.85 -14.57 -16.37 -17.76 -17.79
TF VER IG -14.49 -10.78 -12.15 -12.86 -12.76

Table 3 Vertical displacement for design loads extrapolated from span 100 load test

Deflection (mm)
case 1 case 2 case 3 case 4
OF_VER_OG 9.53 11.33 13.62 13.69
MID_VER_OG 14.05 16.61 19.92 20.31
TF_VER_OG 11.34 12.47 14.37 14.81
OF_VER_IG 11.34 12.51 15.28 15.48
MID_VER_IG 12.05 15.28 18.05 18.28
TF_VER_IG 9.76 11.41 13.02 13.36

2. STATIC LOAD TESTING OF GFRP TELESCOPIC GANGWAY FOR

SUBMARINES

SUMMARY OF WORK DONE

The static load testing of 18m GFRP telescopic gangway developed by M/s. Navnirmiti
Composites is carried at College of Military Engineering, Pune. The gangway is made up of
two spans: Non-extendable span of 10 m and a telescopic span of 10 m with 2m overlap as
shown in Fig.6. Each span is made by assembling 5 individual units of 2m length, consisting
of trusses and deck panels made of GFRP. The GFRP joint modules such as K-Joint and T-
Joints are used for connections. The instrumentation is carried out by mounting 80 strain
gages and 11 LVDTs on the predefined locations as shown in Fig.7 and Fig.8 to record the
strains and the deflections during the static load test. The structure is placed on three

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supports. Three testing phases such as (i) Loading phase, (ii) Unloading phase and (iii)
maximum load beyond the test load phase are carried out.

Side view
Isometric view

Fig. 6 General View of telescopic Gangaway

The total test load is evaluated as 1.524 metric ton. The loading is applied as a uniformly
distributed per metre along the length of the structure, using the sand bags of 43 kg each.
Accordingly, per meter, 2 sandbags are arranged for the test load. In the first phase (loading
phase), the test scenarios are planned in such a way that the loading is carried out with a 25%
incremental loading for each step of 0% - 100% of test load. After the loading phase, about 2
hours retaining period is adopted. In the second phase (unloading phase), the loads are
removed by 25% in each unloading step, till the sandbags are removed completely. In the
third phase (maximum load beyond the test load), the loading is increased from 100% test
load through 25% increment, till the failure is noticed. The measurements from strain gages
and LVDTs are recorded for each test case and are analysed.

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(a) Side view and Top view

Fig 7: Instrumentation scheme of LVDTs for deflection measurements during the load
test of the gangway

Fig 8: Instrumentation scheme of strain gages for strain measurements during the load
test of the gangway

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RESULTS
The maximum deflection and the maximum stresses(table 4 and table 5) are checked against
the same permissible values, which are used during the design of the gangway by the client.
The observations from the analysed data are as summarised as follows:

Table 4 Maximum axial stresses in the non-extendable span

Span Side Testcase Max axial Max axial Max Bending

Comp. Tensile stress
stress stress
(Mpa)
(MPa) (MPa)
SIDE-1 Loading 7.9 1.12 7.6 (C)
Phase
SIDE-2 9.85 2.76 4.65 (C)

SIDE-1 Unloading 7.49 1.22 6.2 (C)

Phase
SIDE-2 10.76 22.70 4.31 (T)

SIDE-1 Max loading 11.12 1.4 9.99 (C)

phase
SIDE-2 11.59 3.4 5.77 (C)
Non-Extendable

Table 5 Maximum stresses in the telescopic span

Span Side Testcase Max Max Max Bending
Comp. Tensile stress
stress stress
(Mpa)
(MPa) (MPa)
SIDE-1 6.02 13.25 8.26 (C)
Loading Phase
SIDE-2 5.36 2.86 2.63 (T)

SIDE-1 5.21 11.32 6.11 (C)

Unloading Phase
SIDE-2 4.63 2.37 2.34 (T)
Telescopic
SIDE-1 Max loading phase 8.18 18.63 12.31 (C)

SIDE-2 7.57 4.15 3.68 (T)

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1. As per the results, the gangway is safe till 125% of the test load, beyond which the
failure is noticed through the slippage of few GFRP members detaching from the two
joints, L7.1 of Side-1 and L7.2 of Side-2, of the 7th individual unit in the telescopic
span. The present mode of failure is seemed to have occurred due to the following
factors:
 The lack of geometrical consistencies and imperfections in the diameter and
thickness of the joint modules which are connecting the GFRP truss members
 The uneven thicknesses of the epoxy coating, applied inside the joint module
to bond the members after inserted into the joint modules.
 Less frictional bond between the inner surface of the joint modules and outer
surface of the GFRP circular members connected in the particular joint.
 Lack of proper locking arrangement for the members to be intact inside the
joint module.

2. Deflections during Loading and Unloading phase:

In the non-extendable span, the vertical deflections are measured from 2 mid-width
locations at 1/4th and 3/4th span and 2 locations at the bottom of inner trusses at 1/2th
span. Similarly, the vertical deflections at 2 mid-width locations at 1/4th and 3/4th span
from mid support and 2 locations at the bottom of the trusses at 1/2th of the telescopic
span are measured. LVDTs are also installed at mid-span on either sides to measure
the lateral deflections of the telescopic span as they are less stiffer than the non-
extendable span.
 Among the four mid-width locations on the GFRP deck, the maximum vertical
deflection of 22.97mm of the structure, is observed in the deck of the
telescopic span, at 1/4th span from the mid-support.
 Among the trusses in non-extendable span, the truss in Side-2 deflects
vertically more when compared to truss in Side-1. The maximum vertical
deflection observed is 30.35mm in Side-2 truss.
 Among the trusses in telescopic span, the truss in Side-1 exhibits higher
vertical deflection when compared to truss in Side-2. The maximum deflection
observed is 30.15mm in Side-1 truss.
 The maximum lateral deflection in telescopic span is 5.58mm towards Side-1.

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3. Deflections during loading beyond test load:

 The vertical downward maximum deflection of 44.7mm, at 150% test load,
during failure, is observed at the mid-span of the truss in Side-1, from the
middle support, in the telescopic span.
 The vertical downward maximum deflection at the mid-width of the deck is
observed as 27.93mm, at 3/4th of the telescopic span measured from the mid-
support.
 Among the trusses in non-extendable span, the truss in Side-2 deflects
vertically more when compared to truss in Side-1. The maximum deflection
observed is 33.75mm in Side-2 truss.
 Among the trusses in telescopic span, the truss in Side-1 exhibits higher
vertical deflection when compared to truss in Side-2. The maximum deflection
observed is 44.7mm in Side-1 truss.
 The maximum horizontal deflection in telescopic span is 11.13 mm moving
towards Side-1.

4. Stresses during Loading and Unloading phase:

 In the non-extendable span, the maximum compressive stress during loading is
observed as 9.85 Mpa in the top-chord of the truss in Side-2. The maximum
bending tensile stress of 3.9Mpa occurs at the bottom chord member in Side-2.
 In the telescopic span, the maximum compressive stress during loading is
observed as 8.26 Mpa in the top-chord of the truss in Side-1. The maximum
tensile stress of 13.25Mpa occurs at the top-chord member in Side-1.

5. Stresses during Loading beyond test load:

 In the non-extendable span, the maximum compressive stress during loading
beyond test load is observed as 11.59Mpa in the top-chord of the truss in Side-
2. The maximum bending tensile stress of 4.65 Mpaoccurs at the bottom chord
member in Side-2.
 In the telescopic span, the maximum compressive stress during loading is
observed as 12.31Mpa in the top-chord of the truss in Side-1. The maximum
tensile stress of 18.63Mpa occurs at the top-chord member in Side-1.

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6. Failure:
 At 150% of test load, the failure is noticed in the form of loosening of joints IS
L7.1 in Side-1 of telescopic span and Joint OS L7.2 in Side-2 of telescopic
span.
 There is no other failure noticed in the GFRP truss members or the deck
panels except the joint loosening of joints ISL7.1 and OS L7.2.

Submitted by

(KAVITHAYINI. R)

Submitted to

Dr.B.ARUN SUNDARAM
PROJECT LEADER,SHML
CSIR-SERC

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