Nov 15 2012
Aluminium can be used as a primary structural component in bridge decks, bridge girders and cross bracing, say the authors of a study on potential applications of aluminium that was completed earlier this year for the Aluminium Association of Canada.
Dr. Scott Walbridge, P.Eng., of the Department of Civil and Environmental Engineering at the University of Waterloo, Ontario, and Alexandre de la Chevrotière, President of MAADI Group, an independent Quebec-based engineering firm specializing in aluminium design and fabrication, reviewed the metal's strengths and weaknesses in their twenty-page report.
"Aluminium alloys have many advantages including low self-weight, high corrosion resistance and extreme durability, not to mention their aesthetic qualities," they write. "The most successful aluminium applications optimize these advantages."
According to Walbridge and de la Chevrotière, these characteristics have already helped aluminium make a breakthrough in work on existing bridges, particularly deck replacement and widening projects and in secondary structures such as pedestrian and bike path additions, street light structures, road sign structures and restraint systems.
Call to key infrastructure players
"Aluminium has been used in the construction of road bridges for 80 years," said Jean Simard, President and CEO of the AAC. "It was first considered for a bridge deck replacement project in Pittsburgh in 1933. But the world's longest aluminium bridge - the Arvida Bridge - was built in Saguenay, Quebec - in 1950. Since then, despite its clearly demonstrated qualities, aluminium has remained highly under-used in major bridge and overpass infrastructure projects.
"That is why we are encouraging architects, engineers and governments to more seriously consider aluminium for the major infrastructure renewal projects planned for Quebec over the coming decade. They should also take into consideration the savings in structure maintenance unlocked by using aluminium."
In their study, the two engineers noted the most common applications of aluminium are in bridge deck replacement projects and in the construction of pedestrian overpasses, lift and bascule bridges, floating bridges and temporary bridges. They also say that many projects have proved the feasibility of building road bridges entirely of aluminium.
The authors point out a number of the material's weaknesses and disadvantages, such as its low elastic modulus, lower fatigue strength compared to traditional steel and high initial cost. However, Walbridge and de la Chevrotière say that these drawbacks can generally be compensated for in the design, by using different welding techniques and by selecting materials based on whole-life cost analysis.