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Structural Health Monitoring

Structural Health Monitoring (SHM) provides a vital link between monitored structures and a central monitoring site. This allows many structures to be monitored at a central site, with information transmitted via the Internet, thereby eliminating costly permanent site installation and reducing the number of site visits. SHM also provide a structured approach to assessing the performance of various ISIS technologies and reporting on successes based on monitoring a number of field projects over extended periods of time. In addition to field projects, numerical modelling and identification of damage using the finite element method and, alternatively, damage detection algorithms, are also being developed. Acceptance of intelligent sensing and structural health monitoring as an essential part of infrastructure design, at a fraction of the capital cost of construction, will be key to developing 21st century “high-tech” civil engineering structures.

In order to advance the acceptance of SHM technology, ISIS has provided leadership to the International Society for Structural Health Monitoring of Intelligent Infrastructure, a non-profit organization of leading structural health monitoring institutions. The goal of the association is to enhance the connectivity and information exchange between participating institutions and to increase the awareness for structural health monitoring disciplines and tools among end users. Dr. Aftab Mufti is President of ISHMII. 

Structural Health Monitoring Support Centre
FOX-TEK Long Gauge Instrument
IDERS Fibre Bragg Grating Readout Instrument
Brillouin Sensing System
Demodulation Systems
Fibre Bragg Grating Sensors
Long Gauge Fibre Optic Sensors
Multiplexed Sensors
Positioner Device
Pultruded Sensors

 

Structural Health Monitoring Support Centre

The Structural Health Monitoring Support Centre is located at the University of Manitoba. Its primary goal is to evolve as a national centre of expertise for providing technical support for SHM and Civionics technologies to field projects across Canada and helping to build regional centres in collaboration with the Network members.

The following items identify the centre’s current goals, in general terms: Promote the use of SHM systems in new and rehabilitated civil infrastructures:

  • Provide technical support on the design, installation and operations of SHM systems and equipment
  • Support for data acquisition, transfer and management of data
  • Maintain live data sites, manage the SHM data from the field projects such that the Network members can access and use it for monitoring and research purposes
  • Develop techniques for efficient data collection, maintenance, presentation and archival
  • Support for integrating SHM systems to the Internet for remote monitoring
  • Provide field training, site visits and develop training and design manuals of SHM systems and Civionics
  • Interact with industry, evaluate and validate SHM equipment and sensors under various field and laboratory environments
  • Engage the industry partners in the development of SHM systems and equipment compatible with ISIS Canada’s guidelines and specifications
  • Build laboratory demonstration facilities to understand and teach SHM technologies and systems
  • Maintain a supply of equipment for use by Network members
  • Keep an eye on new and emerging technologies for SHM systems and identify the practical ones

 

FOX-TEK Long Gauge Instrument

A new automated, computerized long gauge instrument has been designed and manufactured by FOX-TEK Inc. It is faster and more accurate than the manually operated long gauge instrument previously developed by ISIS. This new instrument works in conjunction with the new sensors and is configured to handle up to 16 sensor channels using a commercial optical switch that can be accessed and remotely controlled by a PC notebook computer with associated software that presents the deformation (or strain/temperature) data in a format that can be readily interpreted by users.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

IDERS Fibre Bragg Grating Readout Instrument

The 5100A structural health monitoring system utilizing fibre Bragg grating (FBG) optical sensors was conceived through collaboration between ISIS Canada and IDERS Canada and has since been developed and manufactured in Manitoba by IDERS.

The impetus for a new technology was born from requirements of ISIS Canada to read FBG sensors that were advanced, reliable and could be integrated in systems for structural health monitoring. It has application in all manner of infrastructure and equipment, making bridges, aircraft, pipelines, towers, ships and buildings safer and more cost effective to construct, operate and maintain. ISIS is utilizing these systems on field demonstration projects across Canada.

Contact: Dr. Aftab Mufti, University of Manitoba

 

Brillouin Sensing System

A portable and economical distributed FOS system based on Brillouin scattering for remote monitoring of temperature and strain is being developed. It has been demonstrated that the Brillouin frequency that is actually measured by Brillouin scattering is proportional to temperature and strain. Hence, it is essential to separate them for purposes of determining the structural response.

Contact: Dr. Xiaoyi Bao, University of Ottawa

 

Demodulation Systems

Multichannel FBG Demodulation Instrument: The UTIAS FOS Laboratory has developed a demodulation system that can take strain measurements simultaneously from a number of multiplexed FBG sensors.

Long Gauge Demodulation Instrument: A prototype long gauge demodulation instrument based on fibre Bragg grating sensors was developed and tested to measure corrosion damage on concrete columns. Both laboratory and field tests were successful in demonstrating the performance of this instrument.

A new instrument has been designed that is computer-controlled, more robust and user-friendly with a much higher strain resolution capability.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

Fibre Bragg Grating Sensors

The UTIAS FOS Laboratory has distributed a range of experimental fibre Bragg grating (FBG) optical sensors to the ISIS research community, for qualified research programs. Fibre optic sensors are immune to electromagnetic interference, lightweight, and evidence long term stability when embedded in advanced composite materials. The UTIAS FOS Laboratory also provided ISIS members and researchers with on-site assistance in the installation and measurement of FBGs, as a service to promote the use of fibre optic sensors in civil engineering structures.

Fibre Bragg grating sensors are manufactured using a powerful excimer laser to alter one small section (about 25 to 40-mm) of the photosensitive core of a fibre optic cable. These small sections reflect light at well-defined wavelengths. These are 'single-ended' sensors, since the light enters and is reflected back through the same end.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

Long Gauge Fibre Optic Sensors

Most fibre optic sensors for civil engineering are approximately 1 to 2 cm long and provide measurements of temperature and defined points of strain. Long gauge sensors were developed at UTIAS that can be of any length and are custom-made for specific applications. For example, these sensors have been made with a length equal to the circumference of bridge columns where they have been installed. These long gauge sensors can be used to measure hoop expansion strains. When the steel reinforcements inside a concrete column are contaminated by salt and moisture, the steel begins to rust, expand, and crack the surrounding concrete.

These changes in circumference are detected by the sensors. Indications are that the sensors can also pick up traffic load from the bridges supported by the instrumented columns.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

Multiplexed Sensors

Multiple fibre optic Bragg sensors can be incorporated on a single optical fibre. Each strain-sensing region reflects a different wavelength, providing multiple strain readings from a single optical fibre.

A string of multiplexed sensors enables mapping a whole array of strain measurements by connecting to a single lead. Multiplexed sensors reduce the number of sensors that must be bonded in place, and the number of leads running through and out of a structure, simplifying construction and monitoring. Multiplexed sensors were first installed on the Taylor Bridge in Headingley, Manitoba in 1997.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

Positioner Device

A device developed by the UTIAS Fibre Optic Sensing Laboratory significantly improves the process of 'writing' fibre optic sensors used for research. Called a phase mask holder-positioner, the device is a precision, stainless-steel clamping system for exacting movement and placement of fibre optic cables during the process of 'writing' a fibre optic sensor into the cable.

The positioner is a small steel and aluminum platform mounted at the focus point of the excimer laser. The optical fibre is held in position by placement in a groove across the face of the positioner. Using this device, the position of the phase mask is adjustable; the fibre optic cable itself remains stationary. From a time span of up to an hour or more, the positioner can reduce writing time to as little as two to three minutes, a significant saving in terms of both researcher and facilities-use time.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc.

 

Pultruded Sensors

Fibre optical cable containing multiple fibre Bragg grating sensors have been embedded in pultruded tendon polymer material. Laboratory tests indicate that the embedded fibre optic sensors survived the pultrusion process, and transmitted signals on the strain distribution within the tendon. This is the first step in manufacturing fibre optic sensors that are integrated into the manufacture of advanced building materials, as opposed to FOS installation on existing structures.

Contact: Dr. Roderick Tennyson, FOX-TEK Inc. and Dr. Alex Kalamkarov, Dalhousie University