Ironworkers Memorial Second Narrows Bridge Fatigue Study

This 1.3 kilometre long, steel truss bridge is one of two major bridges crossing the Burrard Inlet between Vancouver and North Vancouver.

The load test involved a full-scale, permit-controlled overload truck placed in the outer lane, where fatigue damage was greatest. The testing was fully strain-gauged, and the results showed that the global and local analyses were effectively capturing key behaviours and trends. Based on the crack patterns observed, analyses, and outside-the-box thinking, we also postulated, identified, and reported on a unique, fatigue-related behaviour in truss or girder bridges having certain floorbeam details. This was presented at the 2009 Fatigue and Fracture Conference in Pennsylvania.

In addition to the fatigue life analyses and investigations, we designed fatigue crack mitigation measures, fatigue and fracture repairs, and strengthening works. These included upgrading a variety of load and distortion-induced fatigue cracks, buckled and deformed elements, corrosion, and deck joint failures.
Construction was completed in 2008. Associated Engineering also provided technical assistance to the Owner throughout construction.