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Canadian Geographic
November/December 1997

Bridge talk


By Jen Ross

"Are you deflecting and straining within the allowable range?"

"I am at 90 percent of my original design capacity and can now manage double the traffic load."

So went a recent "talk" between P.E.I.'s Confederation Bridge and engineers at the University of Calgary and Ottawa's Carleton University.

"We ask a bridge questions and it answers us," says Sami Rizkalla, president of Intelligent Sensing for Innovative Structures (ISIS) Canada.

The system, developed two years ago, uses fibre-reinforced plastic embedded with fibre optic sensors to strengthen and monitor the condition of "smart" structures. The plastic can be wrapped around pillars for repairs or embedded in concrete during construction.

The material, six times stronger than steel, is expected to extend the life of bridges and other structures, although it is too early to know by how much. Fourteen structures in seven provinces now "talk" to ISIS researchers, including nine bridges, a parking garage, highways and buildings.

ISIS's sensors were included in a 60-metre stretch at the centre of the 13-kilometre Confederation Bridge that links P.E.I. and the mainland. The goal is to ensure that any problems in the section, which is subjected to the most pressure and strain, are resolved before they become serious.