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web seminar
Web Seminar
  • You should hear my voice through your PC speaker / headset
  • You can ask questions using the “Questions” panel on the right of your screen. We will answer:
    • In the “Questions” Panel
    • At the end of the presentation
    • By email
  • Later this week you will receive link to:
    • Presentation in PowerPoint and PDF with narration
    • Datasheets

Long-term bridge monitoring

Angelo Figini


Manno, Switzerland


  • Introduction
  • SHM Benefits
  • Return on Investment
  • 7 Steps methodology
  • Monitoring strategies


  • Bridges are probably the most attractive civil structures and they can be built from any of commonly used construction materials: wood, masonry, steel, concrete and recently, composites
  • The importance of bridges as a means of communication has long been appreciated. That’s why particular care is given to the maintenance of bridges with the aim to keep them functional as long as possible
  • SHM certainly contributes greatly to maintaining bridges in service. Fibre-optic sensors with a long-gauge basis, offering the possibility of global structural monitoring, made possible the creation of basic monitoring strategies for bridge monitoring, based on the bridge structural system
main types of bridges
Main types of bridges
  • Beam bridges: horizontal beams supported at each end by piers
  • Arch bridges: arch-shaped and have abutments at each end
  • Cantilever bridges: built using cantilevers, horizontal beams supported on only one end
  • Truss bridges: composed of connected elements
  • Cable stayed bridges: held up by inclined cables
  • Suspension bridges: the deck is hung below suspension cables on vertical suspenders

Visual Inspection: is it enough?

  • The most significant limitation of bridge inspection is that the data collected is based solely upon visual inspection, amplified only with limited mechanical methods such as hammer sounding or prying
  • The Visual inspection is highly variable, subjective and intrinsically unable to detect invisible deterioration, damage or distress
  • There are many types of damage and deterioration that need to be detected and measured that are beyond the capabilities of visual inspection and bridge performance also needs to be measured
shm benefits 1
SHM Benefits /1
  • Monitoring discovers deficiencies in time

A few of your structures might present deficiencies which cannot be identified by visual inspection, and in these cases you can save money by taking actions before it is too late.

Repair will be cheaper and will cause less interruption to the use of the structure if it is done in time.

  • Monitoring discovers hidden structural reserves

Many structures are in much better conditions than you expect! In these cases, monitoring will allow you to increase the safety margins without any intervention.

Monitoring allows a “controlled lifetime extension” of your structure, in a way that you can postpone repair or replacement.

shm benefits 2
SHM Benefits /2
  • Monitoring allows structural management

You can use monitoring data to perform "Maintenance on demand“: optimize the maintenance, repair and replacing of your structures based on reliable and objective data.

Monitoring data can be integrated in structural management systems and increase the quality of your decisions by providing reliable information.

  • Monitoring insures long-term quality

Each quality policy requires measurements and feed-back to insure that the objectives are attained.

By providing continuous and quantitative data, a monitoring system helps you in assessing the quality of your structure.

shm benefits 3
SHM Benefits /3
  • Monitoring increases knowledge

Learning how a structure performs in real or laboratory conditions will help you to design better structures for the future.

This can lead to cheaper, safer and more durable structures with increased reliability and performance.

  • Monitoring increases safety

Having permanent and reliable monitoring data from your structure, you can guarantee the safety of the structure and its users.

long term bridge monitoring why
Long Term Bridge Monitoring: Why?

When making plans for a long term bridge monitoring system, some factors to be considered are:

  • How long do we want to monitor the structure?
  • What type of data do we want?
  • How much data do we want to collect?
  • How will the data be used?
  • Which kind of data management system will be used?
  • What are the initial costs?
return on investment 1
Return on Investment /1

New Bridge:

  • Cost of SHM: 0.5% - 3%
  • Cost of operating SHM over 10 years: 2% – 5%
  • Savings:
    • Discover and repair errors during construction
    • Remedy defects during warranty at no cost
    • Reduce cost of future repair and maintenance
    • Insure quality by checking
return on investment 2
Return on Investment /2

Bridges Candidate for Replacement:

  • Cost of Replacement, without SHM: 100%
    • Cost of SHM: 3%
  • Bridges found to be OK: 20%
  • Bridges needing rehabilitation: 20%
    • Cost of rehabilitation: 30%
  • Bridges needing replacement: 60%
  • Cost with SHM: 3%+20%x30%+60%=69%
  • Saving from SHM: 31% !!!
7 steps bridge shm methodology
7 Steps bridge SHM Methodology
  • Identify bridges needing monitoring
  • Acquire information on probable risks and opportunities from design engineers or owners
  • Establish expected responses
  • Design SHM system to detect such responses and select appropriate sensors
  • Install and calibrate system
  • Acquire and manage data
  • Asses and analyze field data
step 1 indentify bridges
STEP 1: Indentify Bridges
  • New bridges including innovative aspects
  • New bridges with unusual associated risks or uncertainties (geological conditions, seismic and/or meteorological risks, aggressive environment, vulnerability during construction, quality of materials)
  • Bridges that are critical at a network level
  • New or existing bridge which is representative of a larger population of identical or very similar bridges
  • Existing bridges with known deficiencies or very low rating
  • Candidates for replacement or major refurbishment works.
step 2 risk opportunity analysis
STEP 2: Risk/Opportunity Analysis
  • The SHM system designer, the design engineers and the owner, must jointly identify the risks and opportunities associated with the specific structure and their probability
  • The analysis will lead to a list of possible events and degradations that can possibly affect the bridge, their impact an probability
  • The result of this step is a list of risks and opportunities that must be addressed by the SHM system
step 3 identify responses
STEP 3: Identify Responses
  • For each risk and opportunity, associate one or several responses that can be observed directly or indirectly
  • Roughly quantify the expected responses
  • Define locations and risks to be addressed by Inspection and by a SHM system
step 4 design shm system
STEP 4: Design SHM System
  • Select appropriate sensors and technologies
  • Consider the required lifetime of the SHM system
  • Consider the available budget
  • Consider reliability and redundancy
  • Consider installation and schedule

Parallel Topology  Average Curvature

  • Crossed Topology  Average Shear Strain






Cell i


Cell i





Sensor “1”

Sensor “2”






Top sensor

Cell i




Neutral axis


Bottom sensor

Sensor Topologies

  • Simple Topology  Average Strain

Ext. Cables



Central Conn. Box

Intermediate Conn. Boxes



Reading Unit

User's PC

Typical bridge monitoring layout


Central Measurement Point

Wire or Wireless Connection

long term bridge shm requirements
Long Term Bridge SHM: Requirements
  • The system must be able to record slow changes over time, due to loading and environmental effects
  • The whole record of bridge temperature and individual sensor temperatures
  • The residential system must be robust enough and able to operate in a self sufficient manner
  • The data logger must automatically collect data from sensors
  • Application software must post-process raw data and summarize the results
  • The system must be remotely accessible from the office
step 5 installation and calibration
STEP 5: Installation and Calibration
  • Installation and testing of all components
  • Verify correct installation in accordance to the specifications
  • Commissioning, with Site Acceptance Test (SAT) if required
step 6 data acquisition mng


3rd Parties







Other SW


SDB View



SDB Stat

STEP 6: Data Acquisition / Mng
  • Foresee a database management system with documentation of interventions
  • Data storage must be in a standard database format, so it’s easily possible to review historical data
step 7 data assessment analysis
STEP 7: Data Assessment & Analysis
  • By analyzing the responses of the bridge, the engineer will be able to identify if any of the foreseen risks and degradations have materialized and if any of the opportunities are confirmed
  • Establish procedures to respond to the detection of any degradation
  • The analysis of the data might prompt for further investigation, including visual inspection, testing or installation of additional sensors
  • Alerts, warnings and periodic reports.
monitoring strategies
Monitoring Strategies
  • Each monitoring project presents its peculiarities and although it is possible to standardize most elements of a monitoring system, each application is unique in the way they are combined.
  • It is however possible to classify the monitoring components according to few main categories:
      • Scale
      • Parameter
      • Periodicity
      • Response
      • Data Collection
      • Phases
monitoring strategies scale
Monitoring Strategies – Scale
  • Local scale: the performance is analyzed looking at the local properties of the construction materials
  • Member scale: a number of selected critical members are observed for their global behavior
  • Global scale: the structure is observed from the point of view of the overall performance and response
  • Network scale: the monitoring of several structures belonging to an infrastructure system allows the owner to make decision at the system level
monitoring strategies parameter
Monitoring Strategies – Parameter
  • Mechanical: strain, displacement, curvature, rotation, …
  • Physical: material temperature, humidity, ...
  • Chemical: pH, chlorine, sulphate, ...
  • Enviromental: air temperature, humidity, solar radiation, wind, ...
  • Actions: vehicleloads, forces, …
primary monitored parameters
Primary Monitored Parameters
  • By direct monitoring:
    • Average strain
    • Shear strain
    • Rotation & Inclination
    • Temperature & Temp. Gradient

The final monitoring aim can often be achieved by indirect monitoring, i.e. by data analysis of results obtained from primary monitored parameters

indirectly determined parameters
Indirectly Determined Parameters
  • Using appropriate algorithms:
    • Curvature
    • Deformed shape
    • Pressures & Forces
    • Acceleration
    • Prestress losses
    • Relative displacement
    • Absolute displacement
    • Humidity
additional monitored parameters
Additional Monitored Parameters
  • Testing of the bridge
  • Crack monitoring
  • Forces in strands during prestressing
  • Prestress losses in cable and/or strands
fiber optic sensors why
Fiber optic Sensors: Why?
  • Small size and lightweight
  • High sensitivity
  • Multifunctional (great variety in the measurable parameters)
  • Distributed and Multiplexed topologies
  • Insensitive to external perturbations (EM fields, MW radio-frequency & lightning strikes, humidity…)
  • Durability and reliability in demanding environments
  • No need for electrical power
  • Long-distance remote monitoring
  • Compatible with data-transmission network
monitoring strategies periodicity
Monitoring Strategies – Periodicity
  • Periodic: manual measurements at pre-defined intervals (for example once every three months)
  • Semi-continuous: automatic measurements over pre-defined time periods (for example one measurement per hour, for one week every 3 months)
  • Continuous: permanent automatic measurement, for example every hour
monitoring strategies bridge response
Monitoring Strategies – Bridge Response
  • Static: measurement of slowly varying parameters
  • Dynamic: measurement of vibrations and other dynamic responses
monitoring strategies data collection
Monitoring Strategies – Data collection
  • Periodic: sensors are installed but not measured and they are activated only when necessary
  • Manual: Measurements are performed by an operator on site
  • On-line: all data is permanently available on-line
  • Real-time: data is collected on-line and analyzed immediately to allow immediate feed-back to the owner and users

Monitoring Strategies –Phases


  • Construction
  • Testing
  • Service
  • Refurbishment (enlargement or strengthening)
  • Bridge dismantle (rarely)
conclusions 1
Conclusions 1
  • To summarize, long term bridge monitoring can provide quantitative data for network and bridge level management
  • This could contribute to a much greater level of reliability and utility of data necessary for asset management
  • Bridge safety, especially during extreme events, is enhanced by measurement and monitoring of critical bridge components
  • Enhanced safety, reliability and efficient maintenance can result from improved incident detection and assessment
conclusions 2
Conclusions 2
  • It is important to develop a partially automated data analysis methodologies, translating the raw measurement data, into high-level information that can be used for decision-making purposes
  • Global bridge health and performance assessment must and can only be accomplished using quantitative measurement methods
  • Subjective assessment simply is not adequate to meet these needs
  • In the near future we can expect Bridge Health Monitoring Systems to become mainstream
  • Fiber-optic sensors will increase significantly their market share in the global sensor market
  • It is expected that new types of sensor will also appear, but the main development will be in the consolidation, large-scale production and cost reduction of exiting technologies
  • It is easy to predict that SHM in general will see a more widespread application to many types of structure that are currently not monitored or are only visually inspected.
selected reference projects
Selected Reference Projects

The Roctest Group has instrumented the largest number of bridges worldwide

  • Baiersdorf Road bridge – Germany
  • LehrterBahnhof Berlin – Germany
  • Cable stayed bridge in Venice – Italy
  • ColleIsarco – Italy
  • Inabe – Japan
  • Kameura – Japan
  • Pont Adolphe – Luxembourg
  • Tampico – Mexico
  • Corgoviaduc – Portugal
  • Giurgeni – Romania
  • Bolshoi Moskvoretskiy Bridge – RussiaMoscow Bridge – Russia
  • Matarossa – Spain
  • Arsta Bridge – Sweden
  • Göeta Bridge – Sweden
  • Traneberg Bridge – Sweden
  • Bissone – Switzerland
  • Curved concrete bridge in Lugano – Switzerland
  • Lully – Switzerland
  • Lutrive – Switzerland
  • Mezzovico – Switzerland
  • Moesa – Switzerland
  • OA402 – Switzerland
  • Paudeze – Switzerland
  • Siggenthal – Switzerland
  • Thielle Bridge – Switzerland
  • Vaux – Switzerland
  • Vaux FBG – Switzerland
  • Venoge – Switzerland
  • Versoix – Switzerland
  • Ke-Ya Bridge – Taiwan
  • Shu-Yu Bridge – Taiwan
  • Zhee Yen Bridge – Taiwan
  • Dona Ana Bridge – New Mexico USA
  • Horsetail Fall – USA
  • Moristown – USA
  • New Mexico I10 Bridge – USA
  • Rio Puerco – USA
  • Vermont – USA
  • Wotton – USA
  • SalzachbrueckeMittersill – Austria
  • Schladming Bridge – Austria
  • Pont canal – Belgium
  • Champlain – Canada
  • Esplanade Riel – Canada
  • Jacques-Cartier – Canada
  • Joffre – Canada
  • Laviolette – Canada
  • Pont de l’Iled’Orléans – Canada
  • Pont neuf – Canada
  • Peldar – Colombia
  • Vecchio – Corsica
  • Krk Bridge – Croatia
  • Alexandre III – France
  • Bourgogne – France
  • Elorn – France
  • Pont d’Aquitaine – France
  • Pont de Normandie – France
  • Terenez – France
  • Viaduct Millau – France
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