Research Council to examine broken bridge bolts
January 18, 2016 by On-Site Magazine
The Ontario Ministry of Transportation (MTO) has reached out to the National Research Council (NRC), Canada’s “go-to” research and technology organization, to help in their efforts to determine the cause of the failure of the Nipigon River Bridge.
Beginning this week, NRC’s experts in materials analysis and critical infrastructure will analyze some of the damaged bolts taken from the Nipigon River Bridge. They were shipped to NRC’s Ottawa-based labs for further testing.
“We are pleased to work with Ontario’s Ministry of Transportation to analyze the conditions that led to the bolts’ failure on the Nipigon River Bridge,” said Richard Tremblay, General Manager of Construction at the National Research Council of Canada
“The NRC is deploying its best industry-leading experts in materials analysis and critical infrastructure and advanced equipment to arrive at a timely, safe, and lasting solution for Canadians using this important trade corridor.”
Failure analysis will be carried out on the bolts used to hold together two sections of the cable-stay bridge. Work will begin with fracture surface evaluation, metallurgical composition, and mechanical property verifications to ensure conformity with ASTM standards.
NRC is a government-supported research agency that includes a construction and infrastructure materials division. It develops and validates high-performance materials and innovative structural systems that extend service life and develop more reliable condition assessment, long-term forecasting and decision-support technologies for projects like bridge management.
Part of the steel decking in an expansion joint of the cable-stayed Nipigon River Bridge in northwestern Ontario lifted almost 60 centimetres on January 10, reportedly during very high winds. Officials believe the cause of the failure revolves around the breaking of some key bolts within the structure. These bolts are also being used in other parts of the bridge and have since been inspected to confirm their integrity.
No-one was injured but the crossing was closed for almost a day, which severed the Trans-Canada Highway and “cut Canada in half,” said a local politician.
The $106-million project is still under construction and has earned a high profile as Ontario’s first cable-stayed bridge.
The crossing is on Highway 11 located near the municipality of Greenstone, about 250 kilometres northeast of Thunder Bay. It links Ontario to western Canada and carries around 1,300 trucks a day carrying goods worth $100 million. When the bridge was closed trucks were diverted through Sault Ste. Marie and the United States.
Construction on the bridge started in the summer of 2013. The westbound side was opened to two-lane traffic in November last year and completion is set for 2017. It has three towers rising 70 metres above the river, and a main span 139 metres long.
The design and build team included engineers Hatch Mott MacDonald and McCormick Rankin, and general contractor Bot Construction.