ByRajesh Prasad

Executive Director (Metro)Rail Vikas Nigam Limited

Implementation of Structural Health Monitoring System for live Monitoring of the Cable Forces

at Barddhaman ROB

Good Physique

Regular Check ups

Preventive Measures & Medicines

Proper & Timely Cure & Restoration

A KEY TO LONG HEALTH LIFE OF MAN/STRUCTURE

Good Construction

Regular Inspections

Preventive Measures & Materials

Proper & Timely Repairs & Restoration

SCOPE

• Why Structural Health Monitoring (SHM) required?

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

• Methodology and Monitoring

• Output and Report generation

SHM Consists of :-

• Design, Installation, Commissioning of SHMS• 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.

• 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

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

Login Window

First screen after login

Cockpit display

Cable Force and Temperature variation

Live Force on Cable 7001

Month wise variation

• 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

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 04.01.2017 (KN)

Lower limit (KN)

Upper limit (KN)

7001 55.6 33.39 77.28

7002 84.8 72.22 112.95

7003 83.4 69.71 109.44

7016 96.8 84.97 117.01

7017 73.5 50.99 91.21

7018 67.8 41.70 82.26

LOAD TEST AND LIVE MONITORING SAMPLE

Cable No.

Observed Value Reference range

Reading during load test on 30.08.2016 (KN)

Reading on 07.01.2017 (KN)

Lower limit (KN)

Upper limit (KN)

7001 55.7 55.4 33.39 77.28

7002 89.4 84.6 72.22 112.95

7003 75.4 83.1 69.71 109.44

7016 99.8 96.8 84.97 117.01

7017 78.1 73.3 50.99 91.21

7018 75.8 67.3 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• Generation of time

dependent record of structure’s behaviour for further studies/decision.

CONCLUSION