Failure of west abutment of Nipigon River Bridge Report A recent failure (January 2016) of a bridge abutment. The good thing is that all the technical investigation reports are accessible to the public.
The bridge is a two-span cable-stayed bridge, designed with a shorter backspan and a longer main span, creating a permanent uplift tension in the bearings at the west abutment. A similar uplift condition occurs in many cable-stayed bridges.
On Sunday afternoon January 10, 2016, the Nipigon River Bridge on Highway 11/17, a section of the TransCanada Highway across northwestern Ontario, became impassable following the complete fracture of all 40 bolts connecting the tie-down bearing to the main girder bottom flange on the north-west bearing of the bridge. The temperature on the afternoon of the failure was -16 o Celsius with northerly winds of approximately 27 km/h.
Immediately upon the failure of the bolts, the unbalanced weight of the spans, acting through the backstay cables, pulled the north-west end of the bridge deck upwards, coming to rest at approximately 600 mm above the road level. The center-west bearing did not fail, which limited further damage to the bridge.
The new four-lane bridge is being constructed in two stages, with half of the bridge completed and open to traffic at the time of the failure. There were no reported injuries to either the public or to bridge workers. The TransCanada Highway was closed to all traffic for approximately 17 hours while emergency measures were implemented to bring the bridge back down level with the roadway which allowed a return to single lane traffic. During the following weeks, two independent temporary tie-down assemblies were installed at the west abutment to allow two lanes of traffic to safely use the bridge.
Failure Date From the article it is implied, but not clear, that unchecked changes were made to the main truss t…
Failure Date From the article it is implied, but not clear, that unchecked changes were made to the main truss that might have caused the failure. What exactly were those changes? Mentioned were some substitutions of trusses for plate girders and heavy beams - where in the roof structure were those changes made? The fact that the main truss had only 2 inches of bearing on the exterior wall seems to me to be a contributing factor to the suddenness of the collapse. Who was responsible for the foreshortening of the main truss?
Sinclair, T J E. (July 11, 2011). “CTV Building Geotechnical Advice.” Tonkin and Taylor. New Zealand.
At the request of the Department of Building and Housing and the Hyland/StructureSmith consultants working on the CTV investigation, Tonkin and Taylor investigated the geotechnical reports from the CTV design and the conditions of the site at the time of collapse. They found that the original report and foundation design was adequate and did not contribute to collapse. Stannard, Mike. (January
Auckland, New Zealand.
Forensic analysis of the remains of the CTV building for strength capacity and comparison to the original design documents.
In review of David Harding, the Engineer of Record for the CTV Building, the Disciplinary Committee determined that since Harding had resigned his professional registration, they were left with limited recourse other than to publish their findings of fact and accept the resignation. The decision, though, chronicles the history of the CTV Building design and lack of professional oversight.
The New Zealand Department of Building and Housing. (2012). “Appendix L Structural Drawings CTV Building 249 Madras Street Chirstchurch.” The New Zealand Department of Building and Housing, New Zealand.