Built-up Wrought-Iron Compression Member with Missing Stitch Rivets

London Canada's Blackfriars Bridge, fabricated by the Wrought Iron Bridge Company of Canton Ohio, has been in service since 1875. The parabolic top chord of this tied-arch through-truss structure is built-up using seven shapes interconnected by stitch rivets. Recent inspections indicated extensive stitch rivet failures, raising concerns that the fully composite action of the member has been compromised, with ist constituent shapes in danger of separating. The bridge was temporarily closed to both vehicular and pedestrian traffic to facilitate emergency repairs. This paper investigates the loss of compressive capacity of the built-up compression chord due to missing stitch rivets, including preliminary calculation of the effect of the missing rivets in accordance with the provisions of Canadian steel design standards for built-up members.