Annual Report 1998/1999

Outstanding Achievements Fibre Optic Sensing Fibre Bragg grating (FBG) sensors are extremely compact, rugged, and include low-cost integrated optoelectronic microchip-based systems. A milestone has been met with the development of a long-gauge FBG sensor. Until now, only short-gauge lengths have been applied in bridges to monitor slow change over time. While most fibre optic sensors are three to four centimetres long and provide temperature readings and defined points of strain, the new long-gauge FBG sensor, which could be several metres, allows researchers to record displacement of any kind. The Leslie Street Bridge in Toronto has four steel-reinforced concrete columns wrapped in carbon FRP; two of which are instrumented with the first experimental long-gauge FBG sensors ever manufactured or field tested in Canada. In length, the sensors are equal to the circumference of the column. If the sensors measure any degree of expansion, it is an indication that the steel reinforcements have continued to corrode. The FRP wraps will have been successful in halting corrosion, if no expansion is measured. In addition to this milestone, a partnership between ISIS Canada's research theme on fibre optic sensing, based at the University of Toronto, and E-TEK ElectroPhotonics Solutions Corporation (formerly known as ElectroPhotonics Corporation) ensures that university researchers have access to low-cost fibre optic sensors in large quantities. and E-TEK ElectroPhotonics Solutions manufactures the FBG sensors which are being used by ISIS to further its research. The University of Toronto Institute for Aerospace Studies distributes the sensors to universities within the Network. E-TEK ElectroPhotonics Solutions works closely with ISIS on the majority of field applications with fibre optic sensors for remote monitoring. Founded in 1992, it is a space technology spin-off company of the University of Toronto Institute for Aerospace Studies. Its new agreement to provide sensors for ISIS researchers is an example of how the Network interfaces successfully with industry on developing new technology. Fibre Reinforced Polymers Since reporting on field applications in last year's annual report, ISIS Canada has generated, and in some cases completed, 12 new and diverse projects (which is significant in a research context). The majority are for structural rehabilitation, which is not surprising given over 200,000 bridges and structures are considered to be deficient as reported by the Federation of Canadian Municipalities. The more FRP is applied in field applications the more infrastructure owners, consulting engineers, contractors, suppliers and researchers push the boundaries of creative FRP application. The successful completion of one project generates sufficient real-time data to initiate another application that, in turn, takes the technology closer to general acceptance. These prototype projects serve to gain the confidence of the design and construction industry and prove the technology's long-term performance. With a fundamental mission to move the technology from the laboratory to industry, its success is measured by the rate at which decision-makers accept the new technology for conventional practice. The field data collected since 1995 on nine bridges reflects the excellent performance of this material. Patents The FBG sensors are especially well suited for pultruding within FRP reinforcements and prestressing tendons. This means FRP reinforcements can arrive at a construction site with sensors already embedded in the core of the material, as was accomplished with the Joffre Bridge in Sherbrooke, Québec. ISIS Canada has developed a patented technique for recovering the fibre optic cable embedded in continuously pultruded composite parts. The technique ensures that the automated manufacturing process is not disturbed and that it is accomplished easily and inexpensively. Examples of composite parts benefiting from this patent include composite rebar, reinforcing tendons, antennas, rock bolts, marine rigging and stays, beams, girders, and poles. A second patent has been filed for a technology allowing fibre optic gauges to be encapsulated in composite materials. This produces a rod-like carrier with an embedded gauge suitable for application to, or embedding within, structures made of metal, concrete, and larger composite parts. Both technologies were developed as a result of ISIS Canada research projects that were based at the Smart Materials Centre, Department of Mechanical Engineering, Dalhousie University.

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