The Stoneham Bridge, erected in 2011, is distinguished not only by its outstanding architectural and structural quality, but also by its innovative use of hot dip galvanized steel. Both the steel structure of the bridge and the reinforcing steel of the concrete arches and the road surface were hot dip galvanized.
At the early design stage for the bridge, a structural solution using a central pier was excluded on grounds of safety. The bridge had to cross the new Highway 73 in Quebec, Canada, at an unusual angle of 49 degrees. A central pier would also have called for additional measures from a safety point of view such as, for example, the construction of an extra 600 metres of guard rails. The engineers CIMA+ opted for a bridge made of two parallel arches rising up to 20 metres above Highway 73. The concrete arches are 1.5m wide at the base and 2.4m high, and each tapers down to half this width as it rises upwards. The bridge’s clear span is 68.5 metres, and the total width, including arches and overhangs, is 18.5 metres. 34 steel cables, with a diameter of 48 mm, are linked to the road surface steel structure through integrated anchor plates in the concrete arches. Here, the cross girders of the steel structure form the bridge’s spine rather than the longitudinal girders which normally serve this function.
The Stoneham Bridge has been designed for a 75 year life, with maintenance work being limited to replacing elements subject to wear, such as the carriageway surfacing. Since the climate of Quebec is characterised by long, snowy winters, with temperatures below freezing for periods of up to five months, the strongest corrosive elements to which the bridge is exposed comes from de-icing salt. For this reason, corrosion prevention through hot dip galvanizing was used for both the steelwork of the bridge and the reinforcing steel of the concrete arches and the road surface.
Architect: Lemay & Associes
Image: American Galvanizers and Stephane Groleau