2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

Innovative Aluminum Pedestrian Bridges Case Study

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Mr. Benoit Cusson, WSP (Presenter)
Jean-Denis Toupin

In 2017, WSP undertook the challenge of designing two non-conventional aluminum multifunctional walkways for Parks Canada. The designers retained the geometry of the early 19st railway bridges to recall the rich heritage of the industrial era. Aluminum was retained for the structures to emphasize that Parks Canada is looking towards the future with an innovative maintenance free material. Challenges during the design phase include vibration issues, stability of the top chord on elastic supports, ultimate resistance of welded aluminum, welds calculations and thermal expansion impact on multiple aspects.

The 27 m x 4,5 m pony-truss aluminum structures are completely welded and require no assembly on site which is a feat given the constraints imposed by this material. Welding procedures and assembly strategy at the factory will be discussed. Moreover, this case study will also explain how the aluminum top chord was bent to reproduce the typical deviation seen in old railway bridges. Details at the foundations like anchorage rods, bearing devices, and expansion joints will be described to demonstrate the importance of considering the galvanic corrosion issue when designing aluminum walkways.