ByRajesh Prasad, IRSE

Chief Project Manager (M) & Group General Manager RVNL, Kolkata

07.102016 at IRICEN Pune

Bridge Structural Health Monitoring System (BSHM) for live Monitoring of the Cable Forces

at Barddhaman ROB

SCOPE

• Why Bridge Structural Health Monitoring (BSHM) required?

• How Bridge Structural Health Monitoring (BSHM) function in this case?

• Methodology and Monitoring

• Output and Report generation

WHY BSHM?

• New concept and New Technology

• Health Assessment for change of load pattern

• Condition Assessment with the passage of time

• Life Extension Beyond Design life

• Experimental Verification of Design Procedure/Criteria

BSHM Consists of :-

• Design, Installation, Commissioning of BSHMS

• Operation, Maintenance, Data Recording, Analysing and Reporting

• Sensors to measure environmental and structural response factors (F&T).

• Signal acquisition solution, signal verification and temperature adjustment, conversion of signal to digital format etc.

4 –LANE CABLE STAYED BRIDGE, BARDDHAMAN

(During Construction)

4 –LANE CABLE STAYED BRIDGE, BARDDHAMAN

(After Construction)

4 –LANE CABLE STAYED BRIDGE, BARDDHAMAN

(After Construction)

RVNL Kolkata PIU is Implementing Agency M/s GPT-RANHILL(JV) are main Contractor M/s Freyssinet are specialized subcontractor M/s Consulting Engineering Services(India) Pvt. Ltd

(JACOB) are the DDC and PMC IIT Roorkee is the proof consultant Wind Tunnel Test Being Executed By CRRI STUP Consultant for Geometry Control Experts like Dr. Prem Krishna and Shri R.R.Jaruhar Railways and CRS for blocks and approval

AGENCIES INVOLVED

Clear Span(ABT to ABT): 184.429m Main span length : 124.163 m Back span length : 64.265 m No of cable planes : 3 Type of cable in main span : harp pattern No. of cables in main span : 9 per plane No. of cable per side span : 9 per plane Spacing between cables in main span : 12 m Spacing between the cables in side span : 6.881 m Height of centre pylon : 53.798 m Clearance above rail track: 6500mm Maximum height of road surface from rail track level:

7500MM (Road surface to bottommost part of superstructure =

1000mm)

BARDDHAMAN CABLE STAYED BRIDGE DETAILS

• Engineering Challenge confronted…• Superstructure carries 7.5m carriageway and 1.5 m wide

footpath on each side.

• DECK Geometry:Total Length of the Bridge : 188.431 mCP1 to P1 (Steel composite deck) : 124.163 mP1 to CP2 (RCC Deck) : 64.265 mNumber of Lanes in each Direction : 2Cross Slope : 2 %

GEOMETRY OF THE CABLE STAY BRIDGEBarddhaman yard is one of the busiest yard of Eastern Railway and Rajdhani route over Barddhaman station spanning across 8 platforms and 10 tracks.

Cable Stayed Bridge Construction at Barddhaman

Online Video link : https://www.youtube.com/watch?v=aApXrEmwq5U

Cable Stayed Bridge Construction at Barddhaman

Handbook cum Coffee Table Book titled Staying with Cables - A modern construction in new era is at:http://www.slideshare.net/slideshow/embed_code/key/2sfp4LbZIXl1so

• LARSA 4D model for design• Wind tunnel test• Use of precast RCC slabs to avoid scaffolding on deck• Composite structures for easier construction• Monolithic Back Span• Durable painting by epoxy based paint of Akzonobel• Erection scheme • LUSAS model for Construction Stage Analysis • Geometry Control during execution.• ROBO Control (Monitoring System) by M/s Mageba

FEATURES

• For monitoring of the structural health of the bridge during its service life, 6 nos. of sensors have been installed on the stay cables subjected to maximum loads.

• The structural monitoring system issues alarm notification based on measurements by the on-structure instrumentation when pre-defined threshold values of structural loads are passed. Alarm criteria can be configured based on the structural design of the bridge

MONITORING SYSTEM (ROBO-CONTROL)

• Long term monitoring system.

• Measurement of forces on stay cables.

• Compact Monitoring System.

• System sustenance to extreme conditions.

• Graphical data output in web interface with redundant data storage.

MAJOR COMPONENTS OF THE MONITORING SYSTEM

DESIGN

The sensors are placed to measure the various physical performance parameters with the following general requirements

Solution was designed for bridge monitoring application and all components is of such design as to sustain severe environmental conditions and stand for several years of operation.

Hardware and sensors are available on open markets. Alternatively any proprietary components is replaceable with components available on open markets with reasonable modifications to the overall configuration.

Software operating system is based on Windows.

Software application packages is an open source or code available based programs in case vendor unavailability to support the solution at any time in the future

DESIGN

User interface is very easy to operate and very much user friendly.

User interface is Standard Web Browser based to ensure compatibility to any future operating environment.

Bridge Structural Health Monitoring System (BSHMS) is designed to sustain partial damage and the undamaged parts remain operational and not lose real time and stored data.

Manual has been made in electronic format (PDF) and paper copy.

Mageba has on-line auto diagnostic, trouble shooting and support services for hardware and software.

Archived data has on-line controlled access.

SENSOR SCHEME

6(six) Nos. of sensors have been provided on the central pylon and extreme cables to monitor the forces on these critical cables which are subjected to maximum load. (10% of the total Cables need to be instrumented)

Sensors Used SENSOR SCHEME

Electromagnetic Sensors

FUNCTIONAL PRINCIPAL

Electromagnetic measures magnetolastic characteristics (magnetic flux) of the ferromagnetic materials which are in relation with the mechanical stress. Accuracy: + 0.5%

(Comparator)

Data Acquisition UnitDATA ACQUISITION SYSTEM

Key Features

•Lockable Box

•Compact Design

•Redundant Data Storage

•PC Based System

CONSOLE USED

Monitoring Cockpit - Monitoring Cockpit - All measured data All measured data

presented in real timepresented in real time

Min / Max Values

System overview

Actual values of each sensor

Alarm values

DATA PRESENTATION IN WEB FORMAT

INDIVIDUAL GRAPHS

CABLE SCHEME

CABLE SCHEME

CABLE SCHEME

• Placed inside protected box

• Round the clock running

• Data redundancy• Internet connection

required• Uninterrupted power

supply required

SYSTEM INSIDE THE PYLON

Sensor tied up on the required strand Sensor on strand inside the AV tube

INSTALLATION

Onsite calibration Cabling left inside for future connections

Installation of strands & Stressing Freyssinet’s Parallel Strand System (PSS) stay cables - which

has a design life of 100 years and is the most advanced and durable stay cable system in the world today. There are 3 planes of stay cables with 18 cables each. Vibration control dampers have been installed in long stay cables (> 80m) as per CIP recommendations. Sensors for permanent monitoring of forces during service condition, have also been installed in 6 stays subjected to heavy loads. An inspection and maintenance manual for the stay cables has been prepared. 15.7mm 7 wire strand. Erected and tensioned individually, easier to inspect, repair, replace.

Isotension® Method

PARALLEL STRAND SYSTEM

High Fatigue Resistant Wedges

CORROSION PROTECION

Cable No.

No. strands Pop up cable force(kN)

After wearing course

(kN)

Maximum Cable force

(kN)

Minimum Cable force(kN)

Maximum per strand

force(kN)

Minimum per strand

force(kN)

7001 73 3854 3974 5642 2438 77.285 33.399

7002 73 6102 6575 8245 5272 112.949 72.221

7003 73 5898 6561 7989 5089 109.437 69.714

7016 73 6993 7438 8542 6203 117.015 84.975

7017 85 6162 6314 7753 4332 91.214 50.967

7018 85 5601 5736 6992 3544 82.257 41.697

Cable Threshold Values

Derived from Larsa 4 D Model

LOAD TEST

Cable No.

Observed Value Reference rangeReading during load test on 30.08.2016 (KN)

Lower limit (KN)

Upper limit (KN)

7001 55.7 33.39 77.287002 89.4 72.22 112.957003 75.4 69.71 109.447016 99.8 84.97 117.017017 78.1 50.99 91.217018 75.8 41.70 82.26

LIVE MONITORING

Cable No.

Observed Value Reference range

Reading on 06.10.2016 (KN)

Lower limit (KN)

Upper limit (KN)

7001 56.1 33.39 77.28

7002 84.7 72.22 112.95

7003 73.5 69.71 109.44

7016 96.6 84.97 117.01

7017 74.0 50.99 91.21

7018 68.6 41.70 82.26

Main benefits of Structural Health Monitoring:

• Design Confirmation.

• Safety of the structure.

• Understanding behaviour of structures at certain environmental conditions.

• Load Validation

CONCLUSION

THANK YOUTHANK YOU

It was done at the location where maximum stresses in bridge girder assumed Loading on footpath for live load @300 kg/sqm Test load of 160 MT was given for Vehicular Live Load on both the carriage way Vehicular live load is increased and decreased in four stages i.e. at 50%, 75%,

90% & 100% of test load Initial survey to measure deflection was carried out at pre-determined location

as marked on deck/girder before loading. After loading on foot path (live load) survey was carried out and deflection are

measured Incremental loading of vehicular live load was carried out as per stages as

mentioned above.

FEATURES OF LOAD TESTLOAD TEST WAS CARRIED OUT IN MAIN SPAN AT CH. 12.163 TO 25.563M AS PER IRC:SP:51.

Loading on Bridge Deck conducted in following sequences :

FEATURES OF LOAD TEST Deflection are measured after stabilization of the load applied,

normally after one hour period The final load maintained for 24 hours and hourly reading of

deflection was recorded with full load Unloading was carried out at two stages: (1) vehicular live load and

(2) footpath live load. The removal of vehicular live load has been done at the same

sequences as adopted during loading Reading of Deflection was taken at the end of every sequential stages Net deflection was recorded after removal of full load and the same

was compared with original profile (before loading) of the deck It is found that after unloading of entire loads, the recovery of

structure deflection is above 90% (as per guideline mentioned in IRC:SP:51, Cl. 6.8.2 for steel composite structure minimum recovery shall be 75%)

VEHICULAR LIVE LOAD IN CARRIAGEWAY

Axle No.Dimension of supporting block

Block Load on Each (Tonne)

B (mm) W (mm)

1 265 860 27.22 265 8603 265 860

27.24 265 8605 265 860

19.26 265 8607 265 860 6.4

SKETCH OF SURVEY POINTS

SKETCH OF LOADING POINTS

Instrument Used : Automatic Level

Description Date Time (Hrs)

Ambient Temp (oC)

Reading at Survey Point (Reduced Level)

A B C D E F G H I J K L

Location (Chainage in m): 12.163 (A) 12.163 (C) 12.163 (H) 16.163 (A) 16.163 (C) 16.163 (H) 58.163 (A) 58.163 (C) 58.163 (H) 94.163 (A) 94.163 (C) 94.163 (H)

Reading initial 20.08.16 16.00 30.0 39.555 40.112 39.530 39.588 40.149 39.573 39.935 40.378 39.895 39.804 40.315 39.780

After loading on Foot Path (both Side) 25.08.16 11.00 32.0 39.540 40.093 39.512 39.567 40.127 39.550 39.909 40.354 39.868 39.796 40.308 39.773

Reading during Loading : Reading taken after 1 hour of loading (After Stabilization)

After 50% loading 29.08.16 12.10 38.5 39.513 40.065 39.487 39.536 40.092 39.518 39.890 40.337 39.849 39.791 40.306 39.766

After 75% loading 30.08.16 8.00 32.0 39.515 40.060 39.488 39.538 40.085 39.519 39.907 40.347 39.864 39.800 40.309 39.774

After 90% loading 30.08.16 13.20 38.0 39.500 40.049 39.474 39.519 40.071 39.503 39.883 40.329 39.841 39.791 40.304 39.767

After 100% loading 30.08.16 18.20 30.0 39.501 40.048 39.478 39.52 40.072 39.508 39.897 40.338 39.857 39.797 40.308 39.772

Description Date Time (Hrs)

Ambient Temp (oC)

Reading at Survey Point (Reduced Level)

A B C D E F G H I J K L

Location (Chainage in m): 12.163 (A) 12.163 (C) 12.163 (H) 16.163 (A) 16.163 (C) 16.163 (H) 58.163 (A) 58.163 (C) 58.163 (H) 94.163 (A) 94.163 (C) 94.163 (H)

Reading during Unloading : Reading during Loading : Reading taken after 1 hour of Unloading (After Stabilization)

After 90% loading 31.08.16 19.00 28.0 39.507 40.052 39.481 39.528 40.078 39.512 39.902 40.345 39.864 39.799 40.309 39.773

After 75% loading 31.08.16 22.20 27.0 39.516 40.061 39.491 39.537 40.088 39.525 39.913 40.353 39.873 39.801 40.312 39.777

After 50% loading 01.09.16 11.30 34.0 39.516 40.066 39.490 39.541 40.095 39.524 39.899 40.342 39.857 39.795 40.306 39.769

After 0% loading 03.09.16 13.00 34.0 39.534 40.089 39.510 39.559 40.120 39.545 39.903 40.348 39.863 39.793 40.304 39.768

After unloading from Foot Path (both side) 05.09.16 15.55 33.0 39.554 40.108 39.528 39.587 40.145 39.570 39.934 40.377 39.894 39.803 40.313 39.779

Difference between initial and after 100% Loading (Deflection measured) (mm) (-) 54 (-) 64 (-) 52 (-) 68 (-) 77 (-) 65 (-) 38 (-) 40 (-) 38 (-) 7 (-) 7 (-) 8

Expected Deflection (By Designer) (mm) (-) 87 (-) 92 (-) 87 (-) 106 (-) 111 (-) 106 (-) 67 (-) 66 (-) 67 (-) 19 (-) 18 (-) 19

Sl. No. CHAINAGE REF. POINT

INITIAL READING

OBSERVATION AFTER 50% LOADING OBSERVATION AFTER 75% LOADING OBSERVATION AFTER 90% LOADING OBSERVATION AFTER 100% LOADING

READINGDEFLECTION (IN MM)

READINGDEFLECTION (IN MM)

READINGDEFLECTION (IN MM)

READINGDEFLECTION (IN MM)

ACTUAL THEOR ACTUAL THEOR ACTUAL THEOR ACTUAL THEOR

1 12.163 A 39.555 39.513 42.0 33.0 39.515 40.0 49.0 39.500 55 59 39.554 1 0

2 12.163 B 40.112 40.065 47.0 36.0 40.060 52.0 54.0 40.049 63 64 40.108 4 0

3 12.163 C 39.530 39.487 43.0 33.0 39.488 42.0 49.0 39.474 56 59 39.528 2 0

4 16.163 D 39.588 39.536 52.0 39.0 39.538 50.0 59.0 39.519 69 71 39.587 1 0

5 16.163 E 40.149 40.092 57.0 43.0 40.085 64.0 65.0 40.071 78 78 40.145 4 0

6 16.163 F 39.573 39.518 55.0 39.0 39.519 54.0 59.0 39.503 70 71 39.570 3 0

7 58.163 G 39.935 39.890 45.0 16.0 39.907 28.0 23.0 39.883 52 28 39.934 1 0

8 58.163 H 40.378 40.337 41.0 16.0 40.347 31.0 24.0 40.329 49 29 40.377 1 0

9 58.163 I 39.895 39.849 46.0 16.0 39.864 31.0 23.0 39.841 54 28 39.894 1 0

10 94.163 J 39.804 39.791 13.0 3.0 39.800 4.0 4.0 39.791 13 5 39.803 1 0

11 94.163 K 40.315 40.306 9.0 3.0 40.309 6.0 4.0 40.304 11 5 40.313 2 0

12 94.163 L 39.780 39.766 14.0 3.0 39.774 6.0 4.0 39.767 13 5 39.779 1 0

• In order to reduce the effect of fatigue on the stay cables due to oscillations induced by wind or other external phenomena, stay cables of more than 80m length have been provided with Internal Radial Dampers (IRD). 15 such dampers have been installed on the stays

• IRD is composed of three hydraulic pistons placed at 120° angle around the cable. The inner end of the pistons is fixed with a pin joint on a collar compacting the strand bundle. Their outer end is fixed with pin joints to a metallic tube called the guide tube. The damper is fixed rigidly to the guide tube.

• The available stroke for the transverse displacements is +/- 40mm.

INTERNAL RADIAL DAMPERS

Tension

Compression

CABLE STAYED BRIDGE

Basic Principle :- Pylon

Stay Cables

In Larsa 4D these construction stages are simulated so as to get more realistic analysis. As cable elements have been used which are nonlinear in nature, nonlinear analysis is carried out at each stage. The initial structure has been kept with a pre-camber such that after complete construction, the deflection brings the structure to desired finish level.

Fundamental period of vibration of the structure is calculated by creating a 3D model of the structure and carrying out its modal analysis in STAAD Pro V8i/ Midas Civil/ Larsa4D.

DESIGN SIMULATION BY LARSA 4D

Transverse section showing components of Back Span (124.163m)

65mm WEARING COAT

Stage 16•Max moment in Pylon. Utilization ratio <1

Bending Moment diagram

Stage 16•Max moment in Pylon. Utilization ratio <1 Max. deflection is 208 mm (with lane reduction it will become 166mm)

(Dead Load + SIDL) (Two Tracks of 70R wheeled)

Construction Stage Analysis using LUSAS model• Analysis has been done using finite element analysis software LUSAS. • Deck is modeled as grillage of longitudinal and transverse members. • Deck is integral at P1 and CP2. At CP1 pin support with longitudinal

free movement is used representing the Guided PTFE bearings. • At P1 and CP2, elastic spring supports representing the pile stiffness

are used.

• Load Cases : 67