Key Research Accomplishments

Theme 1 (2002-2006):
Intelligent Sensing and Structural Health Monitoring

Director: Dr. J.J. Roger Cheng, University of Alberta

Focus Area 1.1: Fibre Optic Sensing

Bragg Grating Sensing and Demodulation (1.1.1)
Project Leader: Dr. Roderick Tennyson, University of Toronto

2002-03

A successful prototype fibre Bragg grating (FBG) instrument was designed and tested. Improvement over the past year included a superior demodulation system, internal calibration reference sensor, and a new laser based light source capable of 10nm bandwidth. With this large bandwidth, multiple FBG’s can be incorporated on each optical fibre, thus enhancing the demodulation instrument sensor capacity. For practical bridge structures with limited strain requirements, as many as 10 FBG’s can be used per fibre. Dynamic response is up to 100 Hz.

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Brillouin Sensing and Demodulation (1.1.2)
Project Leader: Dr. Xiaoyi Bao, University of Ottawa

2003-04

• Demonstrated the first experiment on simultaneous temperature and strain sensing for distributed sensor system with cm spatial resolution using polarization maintained fibres and photonic crystal fibres
• Discovered a new method of using DC or broad pulse plus narrow pulse to realize distributed sensor system with cm spatial resolution based on Brillouin scattering
• Discovered a new method of Brillouin spectrum width combined with Brillouon frequency to realize simultaneous strain and temperature sensing
• Developed the signal process scheme to detect small stress/temperature point (1cm) using Brillouin gain/loss based distributed sensor system for the first time
• Characterized the strain and temperature dependence of the Brillouin gain/loss spectrum for Pana, Bow tie and Tiger fibres for the first time
• Discovered the multi-peak property in the Brillouin spectrum of the crystal fibre for the first time

2004-05

• Study of simultaneous temperature and strain property with novel crystal fibres. We will design a strain and temperature chamber in one box to prove the capability of simultaneous temperature and strain capability in the experiment.
• Dynamic strain measurement using Brillouin gain based distributed sensor. Dynamic strain measurement has been conducted for concrete column structure deformation monitoring. We applied axial and lateral loads on a composite FRP/concrete column to produce earthquake like deformation.
• Develop the electronics and interface to realize the offset locking based sensing system. The work has been focused on writing interface program to control two DFB lasers offset locked by optical relay line, the frequency counter, pulse generator, digitizer and detection system for sensing process.
• Signal processing to get the spatial resolution shorter than pulse length has been demonstrated for the first time.
• The coherent Brillouin gain/loss based distributed sensor is proposed by considering the phase effect to the sensor system for the first time.

2005-06

• Signal processing schemes for identifying the location better than spatial resolution
  • Rayeligh criteria is proposed and verified to identify multiple strain event
  • Second order derivative to the location and frequency to identify multiple strain event at location accuracy of ½ to ¼ of the pulse length
• Form factor has been introduced in the Brillouin spectrum to identify the cracks and debonding of the concrete and FRP interfacE
• Jacket effects are studied on the strain transfer between the fiber and structures
• Lock-in amplifier is introduced to reduce the bias drift in the optical modulator
• The dynamic Brillouin scattering model is developed to optimize system design for the distributed Brillouin sensor
• The effect of slowing light in the stimulated Brillouin scattering and its impact to the distributed Brillouin sensor is studied.
• The prolonged phonon lifetime due to the transient Brillouin scattering is discovered and studied and their impact to the distributed sensor is studied.

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Laser Light Sources for Fibre Optic Sensing Technology (1.1.3)
Project Leaders: Dr. David Thompson/Dr. John Simmons, McMaster University

2002-03

A single section distributed feedback laser was developed that emitted two well defined wavelengths separated by 9nm. This was achieved by sequentially etching two superimposed gratings with suitably different pitches. Following overgrowth and processing into standard ridge waveguide structures. We achieved 37dB side mode suppression ratio on both lines. Using a 5nm wavelength device and current pumping each line could be tuned by ~6nm.

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2002-03

This year was largely focused on the development of a new FBG interrogation unit to be used by ISIS researchers for the interrogation of FBG sensors installed in civil infrastructure across Canada. We have made significant progress over the last year and are now close to filed testing of the interrogation system. Specifically we have:

• Set specifications for FBG unit --- Specifications for field capable FBG unit including full internet access completed. Briefly each unit will have up to 24 channels each capable of simultaneously taking greater than 100 samples per second. The resolution will be better than 1 microstrain and the long term drift less than 5 microstrain. Via the internet the unit will be fully programmable and data will be able to be retrieved in a number of formats.
• Set architecture for FBG unit --- Architecture for FBG unit set. Rather than relying on a single processor, a multiprocessor architecture was adopted so that different processors could be dedicated to different tasks. This prevents a single processor from being overloaded. This is a significant departure from the PC based approach used in the past and allows a large number of channels to be read out simultaneously at high rates.
• Set design for FBG unit --- Design of FBG unit completed. The design includes a tunable laser source that was manufactured and delivered in May 2003. The design also includes a gas cell combined with an etalon to provide a long term stable wavelength reference.
• Tested algorithms for peak detection --- Bragg sensors are interrogated by sweeping wavelength and determining the wavelength at which a peak in reflected light occurs. Critical to this is the technique used to determine the peak wavelength. Using test data taken with a tunable laser and a FBG sensor several algorithms were evaluated. At least three techniques were found that yield adequate resolution and accuracy. Specifically we determined that fitting to a polynomial peak resulted in accuracy of better than 10 picometers (12 microstrain) and a resolution of better than 0.4 pm (0.5 microstrain).
• Tested first FBG unit --- In March – May 2003 the prototype interrogation units were tested. The performance of the manufactured prototypes was found to be comparable with the lab version. Based on all the tests performed to date we believe that the filed system will meet all the original specifications that were set out under 1.

2003-04

Full field testing of FBG units: FBG units were demonstrated at Headingley on May 30, 2003 and July 30, 2003.  These demonstrations were attended by a number of ISIS representatives including Roger Cheng (U of Alberta) and John Newhook (Dalhousie).  The demonstrations went well and reports were issued to ISIS.  In November one unit was sent to Sherbrooke for a demonstration.  This demonstration also went well and a report was issued by John Newhook.

Issue report on FBG system performance to ISIS researchers: This will largely be a report comparing the performance of the FBG unit to the original specifications set out in April of 2002. All through out 2003 tests have been carried out on prototype units to verify that they meet ISIS specifications.  Strain resolution and sampling rate specifications have been met.  Units have met the challenging goal of maintaining specifications over a temperature range from 0C to 40C.  Comparisons of metal foil strain gauges and FOS gauges on constant strain cantilevers have proven very successful with the maximum deviation being less than 2.6 microstrain with an average of 0.3

Issue report on optimal use of FOS for structural health monitoring: This report has been complied by Evangeline Rivera and also includes information on the installation of electrical strain sensors and the installation of fiber optic sensors.  This report is entitled “Civionics” and has been put together in collaboration with A. Mufti.  We believe this is a significant step towards establishing this important new field.

2004-05

Field testing of FBG units: Over the last year, the FBG sensing unit has been used for field tests at a number of sites across Canada. In June-July, it was used in a test at the Ste-Ėmelie-de-l’Ėnergie Bridge. This test went very well and results for the FBG instrument compared well with conventional instruments. Most of the sensors are doing well. From July until December, the FBG system has been at Drexel University for testing. These tests have proven that the FBG interrogation system is working well, but did reveal the fibre optic sensor coating is an important factor for accurate strain measurement. Significant effort by me, the SHM Support Centre, Lxsix and Drexel was put into tracking down the problem. This included constructing a test fixture to compare different fibre coatings. Polyimide coatings were found to yield the most accurate results. The Drexel report will be forwarded to the RMC. From August to September, one FBG system was run continuously at the Headingly Bridge site. Strain measurements were taken at 100 readings per second over this time period. Some problems with communications to the FBG unit were observed and IDERS is addressing the problem. In September, the FBG was used in a field test on the Confederation Bridge. The test went well and strain data from a number of sensors was recorded. Preliminary analysis of the data was encouraging. In November, the FBG unit was used in a field test on the Beddington Street Bridge in Calgary. This test went well and most of the sensors were still working after more than 11 years. Since the units were shipped from site to site and operated over a range of temperatures, I think these tests represent a good test of the field robustness of the units.

All FBG units completed for use by ISIS researchers: All of the units were completed as of August 2004. These units are now the formal responsibility of the SHM Support Centre. However, as there have been some issues because of laser failure, I will be continuing to provide technical support until the failed sources are replaced.

Characterize one alternative tunable laser source for use in FBG readout systems: One alternative source has been identified and the FBG hardware is being modified to accept this source. The first results are expected before the end of February.

Begin work on FBG based FRP breakdown sensor: Numerical simulations have demonstrated that by thinning the cladding, a Bragg grating can be coupled to the environment and can be used to sense changes in the medium surrounding the grating. A preliminary set of experiments was carried out at McMaster in collaboration with Carleton University using silicon waveguides. The tests proved successful and the sensor was able to sense changes in index of refraction, but the match with simulations was very poor. As a result of these tests, we are pursuing a modified approach using optical fibre with the core situated close to the surface of the cladding. This type of fibre is called D-fibre. We have identified a manufacturer of D-fibre who can also write the Bragg grating into the fibre. This will yield a sensor system that can be easily integrated into FRP.

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Wireless Sensing for SHM (1.1.5)
Project Leader: Dr. Douglas Thomson, University of Manitoba

2005-06

• Development of a portable interrogation system for wireless sensing system constructed from simple low cost modules. The system weights about 10 kilograms and uses a laptop for a user interface.
• Development of new algorithms for the rapid analysis spectral information from the interrogation system, that yielded accurate determination of strain in relatively short times.
• Through up to10 cm of concrete and at a total distance of 50 cm between the sensor and the interrogator antenna, strains can be measured with a resolution of less than 2 microstrain. The measurement takes a few seconds, but over the next year this is expected to be reduced to less than a second.
• Development and demonstration of a strain sensor with microstrain resolution and 10 microstrain repeatability. Over a time span of a few hours this sensor demonstrated stability of a few microstrain.  Over the next year longer term testing for drift will be carried out.

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Focus Area 1.2: Structural Health Monitoring

Intelligent Wireless Remote Monitoring (1.2.1)
Project Leader: Dr. J.J. Roger Cheng, University of Alberta

2002-03

FC Girder Bridges in Alberta:

• Install sensors and monitoring system in the superstructure of Fort Saskatchewan Bridge
• Perform ambient vibration, static and dynamic tests on the bridge
• Numerical modelling and simulation have been completed
• Feasibility study of various rehabilitation schemes for FC Girder Bridges in Alberta

Remote Monitoring System:

• Develop wireless transmission system
• Study various types of sensor interface and sampling and data compression
• Develop portable and economical microchip data acquisition system
• Transmission through radio frequency, internet, or satellite

Health Monitoring of Structures:

• Wireless remote monitoring system in two pipelines
• Collaborate with Dr. Tennyson and Dr. Bao on using FOS in pipelines
• Develop a structural health monitoring for Syncrude mining structures

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Central Monitoring and Management for ISIS Field Applications (1.2.2)
Project Leader: Dr. John Newhook, Dalhousie University

2002-03

• Completed review of existing field projects. Field trips to Alberta, Manitoba and Quebec to meet with field project teams have been completed.
• Worked with Manitoba team to establish field monitoring with live data through a central internet server.
• Assisted Sherbrooke team in establishing website development and layout strategy for pedestrian bridge project.
• Initiated laboratory project to assess static and modal techniques in detecting delamination of FRP repair beams.
• Initiated laboratory project to assess static and modal techniques in detecting damage in steel-free deck systems.

2003-04

• Continued interaction with Manitoba and Sherbrooke teams on on-going monitoring projects
• Participated in development of Civionics manual
• Participated in IDERs field trial of new Bragg unit and independent demonstration at the University of Sherbrooke
• Completed initial investigation of detection of debonding of CFRP flexural strengthening laminates for concrete beams:
  • Experimental testing of 12 beams completed
  • Stiffness and frequency based methods demonstrated not to be sensitive enough for this type of damage
  • Axial laminate strains demonstrated to be sensitive to debonding
  • Detection methods proposed based on strain measurement which include theoretical modelling and data interpretation recommendations which can be adapted to individual field structures
• Initiated investigation into thermal  strain correction techniques for Hall’s Harbour Wharf data
• Experimental investigation of cracking damage in steel-free decks for the purposes of appropriate SHM systems
  • Constructed 1/3 scale six girder steel-free deck bridge model for examination of service load level performance of steel free deck
  • Examined static response of system to introduction of longitudinal cracks in deck – established sensitivity of load distribution, girder behaviour and strap behaviour to these cracks
  • Conducted concurrent modal testing for future examination
• Re-established Confederation Bridge as a monitoring project for ISIS
  • Complete 2^nd annual cycle of ISIS abrasion monitoring
  • Obtained permission for Bragg instrument trial and monitoring of existing fibre optic sensors

2004-05

• Continued interaction with Manitoba and Sherbrooke teams on ongoing monitoring projects.
• Participated in the establishment and management of ISIS SHM Support Centre.
• Completed thesis and began dissemination of results by articles and conferences for an SHM monitoring system for detection of debonding of CFRP flexural strengthening laminates for concrete beams; proposed strain profile based damaged detection method suited to Bragg and Brillouin type fibre optic sensing systems.
• Completed experimental investigation of cracking damage in steel-free decks for the purposes of appropriate SHM systems; established change in static response of system to introduction of longitudinal cracks in deck; established sensitivity of load distribution, girder behaviour and strap behaviour to these cracks; proposed several new damage detection indices for this system.

2005-06

• Continued interaction with Manitoba research teams on on-going monitoring projects
• Assist in management of ISIS SHM Support Centre
• Completed analytical investigation and thesis on cracking damage in steel-free decks for the purposes of developing appropriate SHM systems
• Established theoretical model for damage response
• validated damage detection indices for this system
• Completed monitoring of Fairview Cove project and final report
• Establish data server at Dalhousie for centralized monitoring of project in Atlantic Canada

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2002-03

• A literature review of vibration-based damage detection methods as applied to mechanical or structural systems has been completed. It was found that very little work has been published on the application of these techniques to structures that are more complex than simple beams or trusses.
• A half-scale bridge deck constructed in the laboratory has been extensively instrumented, and dynamic properties have been measured in an undamaged state. Methods to excite the bridge deck to identify natural frequencies and measure mode shapes have been developed. Methods to produce repeatable results have been developed.
• A finite element model of the laboratory bridge deck has been prepared and used to evaluate the potential of applying numerical vibration-based damage detection methods to detect and locate relatively small levels of damage. It was found that damage could be detected and located longitudinally within a distance equal to less than one-half the spacing of measurement points. A method was also developed to locate damage transversely.
• Small levels of damage have been induced in the laboratory bridge deck. Natural frequencies and mode shapes of the damaged structure were measured. The damage was successfully detected and located using vibration-based damage detection methods and a relatively small number of measurement points.

2003-04

• Two prestressed box girders reclaimed from a dismantled bridge were instrumented using conventional strain gauges and accelerometers.  The dynamic properties of each of these were measured first in an undamaged state, and then as several states of small-scale damage were induced.
• The first girder was used to evaluate the ability of vibration-based damage detection (VBDD) methods to detect and locate damage at single locations, while the second girder was used to investigate the use of the same methods to detect and locate damage induced at two locations simultaneously.
• The VBDD methods used were able to determine the location of both single and double damage states with reasonably good accuracy, provided damage was not located too near a support.
• Of significance is the fact that these results were achieved using a relatively small number of measurement points (six or seven evenly spaced longitudinally) and only measurements of the fundamental mode shape before and after damage.
• Refinements to the VBDD techniques have been made to improve their performance.  Data from the girder tests, as well as those from the previous study using a half-scale steel-free bridge deck, have been used to evaluate the refinements.  Continuing efforts at further refinements are ongoing.
• Finite element simulations are currently being used to investigate additional damage states for the box girders.  Simulated measurement data are being generated at a small number of measurement points and the ability of VBDD techniques to detect and locate multiple damage states using a small number of measurement points is being evaluated.
• Results from this study and field measurements have led to the identification of key issues that must be addressed for VBDD techniques to be successfully implemented as part of a structural health monitoring (SHM) program that may be used on real bridge structures.  These include:
  • Repeatability of measurements, influenced by such factors as instrumentation precision and drift, varying environmental conditions, and changing support conditions.  Measurements must be capable of being made with a very high level of repeatability in order for small scale damage to be detected and located;
  • Method of excitation;
  • Number, configuration, and type of sensors; and
  • Type and location of damage.

2004-05

• Measurements of the dynamic properties of the Attridge Drive Overpass in Saskatoon, SK, previously instrumented under ISIS Project 1.3.7, were continued during the 2004/05 fiscal year.
• Data obtained from the Attridge Drive Overpass have been used to further calibrate and refine a finite element model of the bridge. This has allowed the dynamic responses of the structure in various states of damage to be generated numerically. Vibration-based damage detection (VBDD) techniques have been applied using the numerical data to evaluate their ability to detect and locate the damage. Results indicate that small-scale damage can be located longitudinally and transversely provided a sufficient number of sensors are used to characterize the mode shapes.
• The data from the overpass have also been used to quantify the variation of natural frequencies with temperature changes. Results confirm that changes to natural frequencies caused by temperature variations are orders of magnitude larger than those caused by small-scale damage. This issue will have to be addressed in future investigations.
• The uncertainty of mode shape measurements has been quantified when data are obtained using ambient traffic to excite vibrations. Methods of data processing to reduce the level of uncertainty have been established.
• An extensive numerical study was performed to determine whether random excitation can be used to generate the dynamic characteristics of a structure with sufficient repeatability to reliably detect the presence and location of damage using VBDD techniques. It has become increasingly clear from field measurements that mode shapes generated using random ambient excitation sources such as traffic or wind contain a high level of uncertainty, and it has been unclear whether these data could be reliably used. Results seem to indicate that a large number of repeated trials will be required to generate data with the required level of certainty.
• A study was undertaken to optimize the locations of a small number of sensors on a prestressed concrete box girder to detect and locate small-scale damage with the highest possible level of accuracy. Experimental measurements have been made with accelerometers placed in a wide variety of locations, and numerical methods are being used to extend the study to a larger number of possible sensor locations and damage scenarios. The objective of this investigation is to increase the reliability of measured mode shapes, given a limited number of sensors.

2005-06

Measurements of the dynamic properties of the Attridge Drive Overpass in Saskatoon, SK, were continued during the 2005/06 fiscal year.

• The finite element (FE) model of the Attridge Drive Overpass, previously created and calibrated to field measurements, has been used to determine the influence of sparse sensor placement on the ability of vibration-based damage detection (VBDD) techniques to detect (Level I SHM) and locate (Level II SHM) small-scale damage. Procedures used to scale (normalize) mode shapes have been found to have a significant influence on the performance of VBDD indices. When limited in the possible locations for sensors (e.g. along barrier walls and median), it was found that Level I SHM is possible with certain VBDD indices, but that robust Level II SHM requires a denser grid of sensors.
• A numerical study to investigate the influence of temperature variation on the performance of VBDD techniques has been initiated, using the FE model of the Attridge Drive Overpass.
• A numerical study of the Hudson Bay Bridge is currently in progress to determine the influence of different sources of excitation on the reliability of measured mode shapes. Results of this study will provide information regarding the limitations of applying VBDD techniques using modal data generated using ambient traffic excitation, and provide an indication of whether more controlled methods of excitation are necessary for successful implementation of VBDD.
• Laboratory-based experiments have been initiated to investigate the potential for applying VBDD techniques to timber bridges, particularly to detect the presence of deteriorating timber piles.

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2002-03

• A number of conference papers have been presented on vibration based structural health monitoring.
• Important collaborative work was carried out with the Canadian Space Agency, St. Hubert, PQ.
• Finite element models were completed for two ISIS bridges: (1) Crowchild Bridge, (2) Taylor Bridge.
• The Crowchild Bridge finite element model was correlated using experimental vibration data.
• The first stage of computer simulation studies on damage detection in Crowchild Bridge was completed.

2003-04

• A number of conference papers have been presented on vibration based structural health monitoring.
• Important collaborative work was carried out with the Canadian Space Agency, St. Hubert, PQ.
• Detailed finite element models as well as simple girder models were completed for two ISIS bridges: Crowchild Bridge and Taylor Bridge.
• The Crowchild Bridge models were correlated with experimental vibration data.
• Computer simulation studies on damage detection in Crowchild Bridge using the detailed finite element model has been completed.
• Simulation studies using simple girder model and a combination of modal energy based method and neural network technique are in progress.

2004-05

• A number of conference papers have been presented on vibration based structural health monitoring, all of them arising from research sponsored by ISIS.
• Two journal papers on ISIS research are presently under review.
• Important collaborative work was carried out with the Canadian Space Agency, St. Hubert, QC.
• Detailed finite element models as well as simple girder models were completed for two ISIS bridges: (a) Crowchild Bridge, (b) Taylor Bridge.
• The Crowchild Bridge models were correlated with experimental vibration data.
• Computer simulation studies on damage detection in Crowchild Bridge using the detailed finite element model have been completed.
• Simulation studies using simple girder models and a combination of modal energy based method and neural network techniques have been completed.
• The project contributed to the training of highly qualified personnel, including one post-doctoral fellow and two Ph.D. students.

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Active Control Systems for Extreme Dynamic Loading (1.2.5)
Project Leader: Dr. Jean Proulx, Université de Sherbrooke

2002-03

• Health monitoring and vibration control of structures under dynamic loading.
• New project, new field of research, based on damage detection and vibration control of structures
• Background work completed: o Development of damage detection technique, based on repeated forced vibration tests o Application to a full-scale structure (2-story RC building), subjected to increasing levels of simulated earthquakes
• Initiated damage-detection research program with Hydro-Quebec, to be applied to energy transportation structures (pylons). Background for this project: Completed an extensive review of dynamic loading (wind) on pylons and developed three-dimensional finite-element pylon models for dynamic analysis
• Contacted and hired a senior research associate from ETH (Zurich). Dr. Benedikt Weber is expected to join our research group in July 2003

2003-04

• Health monitoring and vibration control of structures under dynamic loading
• Development of damage detection technique, based on repeated forced vibration tests;
• Application to a full-scale structure (2-story RC building), subjected to increasing levels of simulated earthquakes;
• Initial damage-detection research program with Hydro-Quebec, applied to energy transportation structures (pylons).
• Completed an extensive review of dynamic loading (wind) on pylons and developed three-dimensional finite-element pylon models for dynamic analysis;
• Application to a scaled model of a hydroelectric pylon: ambient and forced vibration tests with modal identification techniques

2004-05

• Development of damage detection technique, based on repeated forced vibration tests.
• Application to a full-scale structure (2-storey RC building), subjected to increasing levels of simulated earthquakes.
• Initiated damage-detection research program with Hydro-Québec, applied to energy transportation structures (pylons).
• Completed an extensive review of dynamic loading (wind) on pylons and developed three-dimensional finite-element pylon models for dynamic analysis.
• Application to a scaled model of a hydroelectric pylon: ambient and forced vibration tests with modal identification techniques.

2005-06

• Health monitoring and vibration control of structures under dynamic loading
• Damage-detection research program with Hydro-Québec, applied to energy transportation structures
  (pylons).
• Application to a scaled model of a hydroelectric pylon: ambient and forced vibration tests with modal identification techniques
• Construction of a full-scale 15-m electrical pylon (90 K$) on the University campus
• Development of an ADINA model for the pylon
• In situ dynamic tests on full-scale pylon to characterize vibration properties
• Development of two methods to regularize damage detection algorithms
• Laboratory tests on two small-scale towers to verify damage detection algorithms.

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Data Interpretation of Monitoring Hall's Harbour and Salmon River Bridge (1.2.7)
Project Leader: Dr. John Newhook, Dalhousie University

2004-05

• Completed thermal analysis of Hall’s Harbour data.
• Extracted cores for durability study.
• Hall’s Harbour SHM project completed.
• Conducted visual inspection of Salmon River Bridge.
• Developed monitoring plan for Salmon River based on T1.2.2 results.

2005-06

• Reinstated SHM system at the Salmon River Bridge including new gauges and Civionics
• Obtained Ten Year Evaluation data from Salmon River Bridge
  • Live load strain response, load distribution an composite action
  • Mapped cracked patterns and widths
• Produce performance comparison between initial monitoring data in 1997 and 10 year data in 2005 to show bridge performance and condition is acceptable
• Proposed method for evaluating fatigue performance of concrete bridge deck slabs for Salmon River Bridge
• Collaborated with durability committee to assess GFRP durability for Hall’s Harbour Wharf

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Focus Area 1.3: Demonstration Field Assessments

Portage Creek Bridge Field Assessment (1.3.1)
Project Leader: Dr. Aftab Mufti, University of Manitoba

2002-03

The objective of this research is to assist in the development of a web-based monitoring system for the Portage Creek Bridge. A remote monitoring system was installed in the Portage Creek Bridge on April 25, 2003. The data acquisition system (DAQ) used in this project is a NI system from National Instruments. The DAQ has four SCXI_1520, the universal strain gauge modules which totally host 32 channels for strain gauges, two SCXI_1121, the general signal conditioning modules which totally host 8 channels for 2 triple axis accelerometers, one SCXI_1112, the thermocouple input module which hosts 8 channels for temperature sensors. The sensors connected now are 32 strain gauges, two accelerometers (6 channels) and one thermocouple. Two strain gauges tested were found to be not working and eight strain gauges shift up and down in the range of 200 strain. The DAQ system is running continuously at 32 sampling rate for each channel. A real time LabView program has been implemented to control the DAQ system. A Dell Pentium III computer (Windows XP) is being used to send a real time stream data back to the SHM Server at the University of Manitoba. The data is collected by the SHM Server and published on the web page every five seconds. The FFT analysis is applied to the readings from two accelerometers and this result is also displayed on the web page. A Nuspectra camera was installed to monitor the real time traffic on the Portage Creek Bridge. This pan/tilt/zoom camera can be accessed by up to 20 clients simultaneously via an internet 10/100baseT connection. Only one client can control the camera at a time. The remote monitoring web page for the Portage Creek Bridge can be accessed under the main page www.isiscanada.com. Currently the Portage Creek Bridge web page is running in the basic version and is still under construction. The future development of the web page consists of the following four phases:

• Phase I involves developing a web-based monitoring system that is interactive and easy to understand by engineers as well as technicians and, which will provide real-time data transfer.
• Phase II involves investigating the use of several data filtering techniques to reduce data collection and allow easy access to vital data. It is intended that the data will be sorted in real-time and categorized by Peek Strains for a given time interval as well as Peek Strains for a given excitation.
• Phase III involves correlating the obtained filtered and sorted data with a scale testing model by subjecting the scale model to similar load conditions.

Once a strain and excitation correlation has been made between the scale model and an existing bridge, the model will be subjected to various loading conditions. The behaviours of the model under the various loading conditions will be recorded and used as a based for damage detection on the existing bridge. In Phase IV the active web-based monitoring system will be completed. It is intended that the system will use the documented behaviors obtained in Phase III to produce text-based notification statuses that will display and record when overloads, the exceeding of percent of maximum strain, and when other areas of interest occur. Currently Phase I has been completed in rough form and the investigation of data filtering techniques in Phase II has begun. It is anticipated that Phase II will be complete by the end of August 2003 at which time Phase III will begin.

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Centre Street Bridge Field Assessment (1.3.3)
Project Leader: Dr. Nigel Shrive, University of Calgary

2002-03

• Data acquisition remotely – still occurring (second winter coming through).
• FE model completed.
• Testing arranged for Dalhousie with student exchange for May – Aug. 2003.
• Comparison of FE/Actual behaviour begun.
• Dynamic tests on bridge performed. Some data analysis completed.

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2002-03

During the reporting period:

• We developed a new fibre Bragg interrogation method that combines swept wavelength lasers in combination with gas cells for a long term wavelength standard accurate interpolation of peak wavelengths
• Tests were conducted to improve the accuracy of the fibre optic sensors. Experimental data have resulted in resolutions of better than 1pm. We expect this accuracy to be maintained over a long period of time as it is based on absorption lines in the gas cell
• Further work involves mounting the Bragg grating on a cantilever test structure and observing the FBG readout unit’s performance under different load conditions. We also plan to incorporate an etalon as another wavelength reference in order to improve measurement accuracy

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Saskatoon Overpass Field Assessment (1.3.7)
Project Leader: Dr. Leon Wegner, University of Saskatchewan

2002-03

• The Attridge Drive Overpass in Saskatoon has been instrumented with a total of 53 conventional strain gauges, bonded in groups of three to the webs of girders.
• Data from these strain gauges and six accelerometers, temporarily installed at 21 locations, have been used to measure the dynamic properties of the structure.
• A base-line signature of the dynamic response has been measured, with the three lowest natural frequencies having been accurately determined, and corresponding mode shapes identified approximately.
• The effectiveness of ambient traffic to excite vibrations has been evaluated. It has been found that ambient traffic can be used to measure the dynamic response, provided that heavy vehicles make up a portion of the normal traffic on the overpass. However, forced vibrations may be required to measure mode shapes accurately enough to be used in damage detection algorithms.
• The effectiveness of the two types of instruments has been evaluated. Strain gauges can be used to measure the quasi-static response, but have been unable to accurately measure the dynamic response due to very low amplitude strains and low signal to noise ratios. Accelerometers are effective in measuring the dynamic response.
• A relatively coarse finite element model of the overpass structure has been developed, and dynamic characteristics have been generated. These have been found to correlate well to measure frequencies and mode shapes.

2003-04

• The dynamic response of the Attridge Drive Overpass in Saskatoon has been measured periodically over the past year at various ambient temperatures ranging from approximately -20°C to 20°C.  Dynamic excitation was accomplished using ambient traffic.
• The effect of temperature variation on natural frequencies and mode shapes has been quantified.  Over the 40°C temperature range, the fundamental natural frequency was found to vary by approximately 9%, while the modal assurance criterion (MAC) between fundamental mode shapes measured at the extremes of this temperature range was approximately 0.92.  These changes to dynamic properties caused by temperature variation are significantly greater than those caused by inducing small states of damage in laboratory studies.
• The use of ambient traffic for dynamic excitation has resulted in levels of repeatability between subsequent measurements that are significantly lower than those found necessary to successfully locate damage in the laboratory.
• These results highlight the need to focus on developing methods to isolate the effects caused by temperature variation from those caused by damage.  In addition, excitation methods and the use of advanced techniques for modal identification using ambient excitation must be further investigated.
• A finite element model of the structure is currently being calibrated to physical measurements and is being used to simulate damage to determine its influence on dynamic properties, to simulate temperature variation to determine its influence on dynamic properties, and to assess the use of vibration-based damage detection techniques to locate damage on a full-scale bridge structure.

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Monitoring Sprayed Bridge in B.C. (1.3.8)
Project Leader: Dr. Nemkumar Banthia, University of British Columbia

2002-03

This demonstration project involves strengthening of Safe Bridge near Duncan, B.C. by applying a sprayed fibre reinforced polymer (SFRP) coating and monitoring of this bridge over time. The accomplishment for this year include:

• Continuous monitoring and performance assessment using sensors on the bridge.
• Non-destructive testing of SFRP coating to detect any debonding.
• Full scale load testing of bridge to monitor performance.

2003-04

This demonstration project involves strengthening of Safe Bridge near Duncan BC by applying a sprayed fiber reinforced polymer (SFRP) coating and monitoring of this bridge over time.

The accomplishments for this year include:

• Installation of WebDeck d/a system at the site for continuous monitoring of the sprayed composites using data from sensors; 
• Continued assessment of the sprayed composite via non-destructive testing at the site and tests in the laboratory; 
• Third and final full scale load testing of bridge to monitor performance.

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Structural Health Monitoring of Golden Boy (1.3.9)
Project Leader: Dr. Aftab Mufti, University of Manitoba

2002-03

In the last year, Structural Health Monitoring of the Golden Boy has advanced according to schedule. The first task accomplished was the installation of the instrumentation around the circumference of the newly replaced stainless steel armature. This instrumentation included traditional multi-rosette gauges, thermocouples, and Fibre Optic Sensors (FOS) located near the fixity of the armature. The three gauges were installed in such a manner that North, South, East and West measurements could be obtained. Next two tri-directional accelerometers were installed at the tip of the armature, which terminates near the inside of the Golden Boy’s torso. Once the restoration process was completed and the Golden Boy relocated on his perch at the tip of the Manitoba Legislative Building, the next phase began. Lead wires were spliced and extended down through the dome to the nearest monitoring point located inside the legislature about 100 feet from the Golden Boy. Since this area was not heated, temperatures in winter could reach far below zero degrees Celsius. To solve this problem, a well insulated shed was built, after which instrumentation leads to the main computer were installed. Also, a camera was mounted on top of the legislature to provide a visual feed for the web page SHM monitoring site. The shed was used as the main terminal. All data was sent via the Internet to the main server located in the Structural Health Monitoring Lab at the University of Manitoba. A web page has been constructed for all Structural Health Monitoring sites in the ISIS Network. The live data from these sites is continuously being recorded and monitored, and since there was a great deal of public interest in the rehabilitation of the Golden Boy, the web page gives the public the opportunity to view the monitoring of this heritage statue, as well as other SHM sites. Future plans include installing wind metres near the Golden Boy to study wind effects and investigating the correlation between the theoretical and actual results of wind action on the Golden Boy, and how these results compare to the wind model test performed at the University of Toronto.

2003-04

The following accomplishments have been made in the study of the SHM of the Golden Boy statue:

• The statue is equipped with intelligent sensors (strain gauges, accelerometer, thermocouples and FOS), an ultrasonic wind meter and live web camera installed at the north-west corner of the Legislature’s roof top.
• The SHM system comprising of acquisition, communication, intelligent processing, storage and retrieval of data was effectively accomplished.
• The SHM network consists of the DAQ system connected to the on site computer which sends the data by remote transfer via internet cable modem connection to the central computer server housed at the University of Manitoba (SHM Lab) is correctly completed.
• The construction of a web page for all SHM projects around the ISIS network for the intention of the public and engineering pleasures
• A mathematical model of the Golden Boy is completed
• Two different theoretical analyses were performed on the collect data (wind meter and accelerometer) for different wind speeds
• A numerical integration method is applied to the ultrasonic wind meter data which converts the forcing function (wind) into a dynamic displacement using the mathematical model
• An analysis on the accelerometer data was done in collaboration with the mathematical model
• An in-depth analysis on the strain gauge data was performed to correctly establish strain and stress results for different gusts of winds
• Confidence in the instrumentation devices (sensors) were confirmed through the study, meaning the instruments are properly functioning and recording data
• Final results were compared and confirmed some sense of correlation between the strain gauges and both theoretical analysis
• Baselines and boundaries are set for the early stages of the SHM process
• The natural frequency of 3 Hertz is calculated throughout this study by the FFT analysis of the live data and theoretical model.  This frequency states that the Golden Boy is in very good health and ay change would need some kind of examination
• The calculation of maximum strain given a gust of wind can accurately be predicted
• The accelerometer provides an alternative method to the actual strain profile measured during any given day, if the strain gauge so happened to malfunction
• Conclusions and Recommendations for future work on the SHM of the Golden Boy are provided in the study

2004-05

• A final report on the SHM of the Golden Boy was completed.
• The damage detection of the shaft was investigated using vibration based damage detection algorithms which will provide a baseline for the future health monitoring of the Golden Boy.
• The natural frequency of the Golden Boy was determined to be 3 Hz which, in turn, will be used as the reference value for a healthy structure.
• Recommendations and conclusions have been provided in the report so that the mathematical model can be refined to achieve the perfect correlation between the strain gauges and the vibration based damage algorithms.
• SHM data from the Golden Boy is now automatically stored on the ISIS SHM database for secure and flexible access by researchers.

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Monitoring of FRP-Reinforced Pedestrian Bridge, Université de Université de Sherbrooke (1.3.10)
Project Leader: Dr. Pierre Labossière, Université de Sherbrooke

2002-03

• Design Competition: Initiated in the Fall of 2002.
• Selection of the winning design: unveiled at the ISIS Conference 2002
• June 2002: Meeting of the winning design team with the civil engineer and architects of the Faculté de genie project, to finalize the design
• Fall 2002/Winter 2003: Construction of the pedestrian bridge on the Université de Sherbrooke campus
• Since April 2003: Installation of the FOS, other instrumentation and data acquisition system

2003-04

Construction of the pedestrian bridge was completed in March 2003 and all the bridge instrumentation except the accelerometer was installed by May 2003.  It had been planned to program the software for remote monitoring in two steps.  The first step, which consisted in the data acquisition from the FOS was completed during the summer of 2003.  Programming the software for data acquisition of the accelerometer and from a digital photo camera to detect and identify the nature of special loading events was completed in December 2003.  All data acquired should be made available by remote monitoring through a dedicated web site.

The project described above generally proceeds according to original schedule for research issues such as programming the data acquisition and development of the web site.  However, there were unexpected difficulties in securing the location of the computer dedicated to data acquisition.  Since it is located in a rather accessible area near the pedestrian bridge and the faculty entrance, it has been necessary to install additional security equipment and alarm devices.  This issue has recently been resolved in collaboration by the Faculty of Engineering, and the computer box has been secured in May 2004.

The accelerometer will be permanently installed under the pedestrian bridge by June 2004.  We plan to conduct series of static and dynamic loading tests starting in July 2004. The web site of the pedestrian bridge will be on line in the Summer 2004.

2004-05

• Construction of the pedestrian bridge completed in March 2003.
• All the bridge instrumentation except the accelerometer was installed by May 2003.
• Software: data acquisition from the FOS was completed during the summer of 2003.
• Software: data acquisition of the accelerometer and from a digital photo camera to detect and identify the nature of special loading events was completed in December 2003.
• The accelerometer was permanently installed under the pedestrian bridge in June 2004.
• Difficulties in securing the location of the computer dedicated to data acquisition: problem solved in collaboration with the Faculty of Engineering, computer box secured.
• All data acquired were supposed to be made available by remote monitoring through a dedicated web site. Due to various hardware and software conditions, the web site of the pedestrian bridge has been on-line and off-line, on an irregular pattern, since the fall of 2004.
• Project officially concluded as of April 1, 2005.
• Pedestrian Bridge and its data acquisition system will remain accessible for the coming years as an ISIS demonstration project.
• Upgrades to the data acquisition system, performing of loading tests, and web page will be undertaken as part of undergraduate or graduate projects.
  Projects aimed at improving data interpretation via signal analysis have been proposed.
• Monitoring experience to be considered for potential integration in new structural laboratory at the Université de Sherbrooke and for a potential Civionics Laboratory.

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Rehabilitation of Corrosion-Damaged Flexural Bridge Girders in the Region of Waterloo (1.3.11)
Project Leader: Dr. Khaled Soudki, University of Waterloo

2003-04

• Region of Waterloo announced Stantec Ltd as the consultant that will undertake the bridge rehabilitation project in March 2004. Stantec Ltd will work with the Waterloo group on the repair design expected in Spring 2004.
• Structural assessment and design of the optimum FRP repair scheme - this stage will be conducted by the research group at Waterloo in consultation with ISIS Theme 4 - Technology Utilization
• Structural health monitoring of corrosion expansion in CFRP wrapped corroded cylindrical prisms (on going).  36 prisms subjected to different levels of corrosion and FRP repair.
• Prototype beams with SHM sensor will be constructed in the laboratory to gain confidence in using sensors and correlate with field measurements.
• Strong links are established with several industrial and government partners including SIKA Canada, Canadian Construction Control, Regional Municipality of Waterloo and the Toronto District School Board. Dr. Soudki has acted as consultant on few projects involving the use of FRPs in rehabilitation of bridges and structures.

2004-05

• Stantec Ltd. deemed that the original bridge proposed by the Region for FRP repair will not be repaired but instead will be demolished and a new bridge will be built.
• Region of Waterloo has proposed another bridge with corrosion damage – The Schiefele Bridge in the town of Conestoga. The ISIS Waterloo group conducted a condition assessment of the structure.
• Design of the optimum FRP repair scheme will be conducted by the research group at Waterloo in consultation with ISIS Theme 4 - Technology Utilization.
• Structural health monitoring of corrosion expansion in CFRP wrapped corroded cylindrical prisms. 36 prisms subjected to different levels of corrosion and FRP repair (complete).
• Prototype beams with SHM sensor will be constructed in the laboratory to gain confidence in using sensors and correlate with field measurements.

2005-06

• FRP Repair was carried out on a girder in the Schiefel bridge in the town of Conestoga of the Region of Waterloo during the period of August – September 2005
• Structural health including conventional gauges, corrosion sensors, thermocouples and FOS instrumentation were mounted in September 2005
• The structure is being monitored since September 2005
• Prototype beams will be constructed in the laboratory to correlate with field measurements.

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Structural Health Monitoring of Provencher Pedestrian Bridge (1.3.12)
Project Leader: Dr. Aftab Mufti, University of Manitoba

2003-04

Section I: Fibre Optic Sensors (ISIS Canada Contribution)

• Fibre Optic sensors were installed by ISIS students and research technicians
• The conduits were installed inside the bridge structure
• The lead wires were pulled from the sensors’ termination boxes to the main control room
• The readout unit for the fibre optic sensors was designed by IDERS and it is being tested and calibrated at University of Manitoba

Section II: Electronic Sensors (City of Winnipeg/Wardrop Contribution)

• All bridge contract work was completed including SHM control cabinets, conduits, lead wire pulling, … etc.
• The bridge was open for public on December 2003
• 75% of the electronic sensors were installed
• Data Acquisition System for electronic sensors was assembled and ready for site installation

2004-05

• All installed sensors were hooked up to the data acquisition systems.
• The two DAQ systems are fully functional at the bridge site.
• The data are being collected and hosted by ISIS Canada server.
• Connectivity testing of the Fibre Optic lead wires was conducted.

2005-06

1. Working with the City of Winnipeg to operate the SHM System at the bridge
2. Investigate possible repairs to the DAQ system, which was damaged by flooding of the west abutment

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Structural Health Monitoring of Pipelines with Brillouin Sensors (1.3.15)
Project Leader: Dr. Xiaoyi Bao, University of Ottawa

2003-04

• Demonstrated the first experiment on steel pipe buckling process monitoring with distributed Brilloluin sensor system with cm spatial resolution
• Demonstrated the first experiment on steel pipe wall thinning process detection under various pressures using distributed Brillouin sensor system for the small defect of 1cm

2004-05

• Design the experiment to measure the buckling of the pipeline using distributed sensor system. The experiment has been designed and conducted for the pipeline-bucking test; we have successfully located the buckling point and measured compression and tension around bucking point.
• Developed the signal-processing scheme to fit the Brillouin peak and search for appropriated strain reading associated buckling process.
• Excavation test has been conducted with Brillouin sensor system to measure the strain change.

2005-06

• This phase of research is to develop the special spectrum de-convolution method to fit the multiple-peaks. We have been very successful on this to get the compression and tension for the pipeline buckling tests.
• Due to large compression in steel, the normal single mode fiber was broken at ~1% stretching level. In this phase of the research we have been searching for the special fiber coating to allow much longer stretching level. So far we have tried carbon coated fibers with much longer extension level of ~3%.

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Life Cycle Costing and SHM to Reduce Freight Costs (1.3.16)
Project Leader: Dr. Gordon Sparks, University of Saskatchewan

2003-04

Instrumentation (accelerometers and strain gauges) has been installed on the Hudson Bay bridge and used to evaluate the performance of the structure under forest truck loadings.  The data gathered has been used to create base line finite element models of the bridge.  Although planned strengthening of bridge girders has been postponed because of provincial budget cuts, the base line data and models will be compared against future data when existing (steel) straps are removed from centre span girders and ultimately replaced with CFRP wraps.

It should be noted that the Hudson Bay bridge project has been subject to preliminary life cycle costing investigation under project # 4.1.1 (see above).  Although budget cuts affect one aspect of the project, the baseline models developed will, in time, prove valuable to the on-going development of relevant LCE&C tools.

2004-05

Instrumentation (accelerometers and strain gauges) has been installed on the Hudson Bay Bridge and used to evaluate the performance of the structure under forest truck loadings. The data gathered has been used to create baseline finite element models of the bridge. Although planned strengthening of bridge girders has been postponed because of provincial budget cuts, the baseline data and models will be compared against future data when existing (steel) straps are removed from centre span girders and ultimately replaced with CFRP wraps.

It should be noted that the Hudson Bay Bridge project has been subject to preliminary life cycle costing investigation under Project #4.1.1. Although budget cuts affect one aspect of the project, the baseline models developed will, in time, prove valuable to the ongoing development of relevant LCE&C tools.

2005-06

Instrumentation (accelerometers and strain gauges) has been installed on the Hudson Bay bridge and used to evaluate the performance of the structure under forest truck loadings.  The data gathered has been used to create base line finite element models of the bridge.  Although planned strengthening of bridge girders has been postponed because of provincial budget cuts, the base line data and models will be compared against future data when existing (steel) straps are removed from centre span girders and ultimately replaced with CFRP wraps.

It should be noted that the Hudson Bay bridge project has been subject to preliminary life cycle costing investigation under project # 4.1.1 (see above).  Although budget cuts affect one aspect of the project, the baseline models developed will, in time, prove valuable to the on-going development of relevant LCE&C tools.  The strengthening of this bridge is now scheduled for summer 2006.

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Data Management and Signal Processing for SHM (1.3.18)
Project Leader: Dr. Dean McNeill, University of Manitoba

2004-05

• Established a central, high-capacity, secure data server which forms the basis for the data management component of the ISIS SHM Support Centre.
• Set up continuous data collection from the Portage Creek Bridge (Victoria), Golden Boy Statue (Winnipeg), and the Esplanade-Riel Pedestrian Bridge (Winnipeg).
• Provide secure online access to archived measurements from the Taylor Bridge (Winnipeg), Confederation Bridge (NB/PEI), Syncrude Crusher (Alberta), IDERS FBG readout unit tests, and individual laboratory tests.
• Developed a novel event detection system, based on neural computation for automated SHM data processing.
• Demonstrated the ability of the novel event detection to perform data reduction/decimation on existing measurements.

2005-06

• Developed PC application (Data Dragon) to perform basic novelty detection and data decimation on a collection of SHM measurements. This program accepts measurement data from text files in tabular form and, with no specific guidance from the user, trains a novelty detection neural network that then examines the original data files
• Extended novelty detection work by performing classification of simulated vehicle traffic as observed from a series of strain gauges similar to those which will be in operation on the Red-River North Perimeter Bridge in Winnipeg. This is preparatory work for the collection and processing of actual measurements from this structure.
• Explored extensions to the novelty detection and decimation algorithm that will allow for continuous adaptation to changes in sensor response over the short-term (a few months) while retaining the historical baseline knowledge of the system in its original state. This would provide the ability to identify both short-term and long-term variations in a structure’s response.
• Deployed a second central, high-capacity, secure data server that provides data management and secure backup of ISIS SHM Support Centre data. (Portage Creek, Golden Boy, Taylor Bridge, Esplanade-Riel Pedestrial Bridge, Syncrude Crusher, McQuade lab tests, etc.)

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Development of Monitoring Technology for the Confederation Bridge (1.3.19)
Project Leader: Dr. John Newhook, Dalhousie University

2004-05

• Completed 3rd annual cycle of ISIS abrasion monitoring.
• Conducted Bragg instrument trial and monitoring of existing fibre optic sensors.

2005-06

• Continued ICE Abrasion Assessment monitoring – year five comparisons
• Evaluated Bragg grating instrumentation for monitoring
• Installed continuous remote on-line monitoring system for fibre optic sensors
• Developed SQL database and GUI for confederation bridge data
• Coded primary visualization tools for slow speed data logging

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2004-05

• Part of the outdoor plaza deck at the University of British Columbia’s Aquatic Center was resurfaced using a high performance fibre reinforced concrete (HPFRC) mixture with shrinkage compensating admixtures. Previous resurfacing efforts had produced unsatisfactory results with overlays exhibiting excessive cracking, premature delamination and unwarranted saturation.
• Two adjoining overlays were placed, one with plain concrete and the other with HPFRC. The overlays each contain embedded sensors to monitor strains, temperature variations and the chemical environment in the overlay to better understand the reasons for debonding.
• Continuous data acquisition over the Internet using the Web DAQ/100 data acquisition system.
• Demonstration that by using advanced concrete technology and fibre reinforcement in concrete, the overlay strains can be reduced by over 18%.

2005-06

• Part of the outdoor plaza deck at the University of British Columbia’s Aquatic Center was resurfaced using a high performance fibre reinforced concrete (HPFRC) mixture with shrinkage compensating admixtures. Previous resurfacing efforts had produced unsatisfactory results with overlays exhibiting excessive cracking, premature delamination and unwarranted saturation.
• Two adjoining overlays were placed, one with plain concrete and the other with HPFRC. The overlays each contain embedded sensors to monitor strains, temperature variations and the chemical environment in the overlay to better understand the reasons for debonding.
• Continuous data acquisition over the Internet using the WebDAQ/100 data acquisition system.
• Demonstration that by using advanced concrete technology and fiber reinforcement in concrete, the overlay strains can be reduced by over 18%.

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Fairview Cove Terminal Underwater FOS Field Project (1.3.21)
Project Leader: Dr. John Newhook, Dalhousie University

2004-05

• Completed installation of first sub-marine use of Bragg and Fabry-perot type fibre optic sensor based SHM system.
• Collected readings during construction to demonstrate satisfactory performance of innovative design.

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