FRONT of HOUSE — December 2012
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New Ottawa Bluesfest Reports Point to Wind Wall Ties as Key Factor in Collapse

OTTAWA, Canada — Although Ontario Ministry of Labor officials issued a report earlier this year finding no evidence of structural defects that led to the July 18, 2011 collapse of the overhead stage structure during a Cheap Trick performance at the Ottawa Bluesfest, newly-published details cite the crew’s inability to quickly cut ties securing the structure’s fabric walls as a key factor contributing to wind loads on the structure as the storm hit the area.

The Ottawa Citizen reported the new details, some of which were obtained via freedom of information legislation, in a story posted Nov. 19, 2012.

Citing the portion of the Ottawa Ministry of Labor report written by engineer Robert Molina, The Citizen noted that crew members had trouble cutting ties securing the side and rear wind walls to the truss as the storm approached. Most of the fabric was still lashed to the structure when gusts of at least 117 km/hour lifted it upward, then backward, away from the crowd, but still on top of band and crew members as the structural elements fell.

The report cited structural design specifications that call for the fabric wind walls to be released when winds exceed 80 km/hour. With those walls released, the structure itself should be able to withstand winds of up to 120 km/hour, the newspaper noted.

The Citizen also interviewed crew members who were working on or near the 45-by-17-meter stage structure, rented to the festival organizers by Groupe Berger, in a separate story published Nov. 18.

That account depicted one crew member trying to use wire cutters to free the stage structure’s fabric walls, and another who, in desperation, stabbed the fabric itself with a knife and saw that panel rip open by the force of the wind.

Both Molina’s report and a separate report written by Ontario Health and Safety inspector Jason Gordon noted that the same stage structure had withstood strong winds from a storm the week before, right before The Black Keys were set to perform.

During that storm, crew members were able to quickly cut the fabric wall ties. Molina’s report suggests that on the night of the collapse, the fabric wall ties were of a different material, harder to cut with just a knife.

Molina’s report also cited “a number of construction irregularities” that, while “not a direct cause” of the collapse, “demonstrated poor workmanship in the assembly of the stage,” including column segments secured with fewer bolts than specified, and the use of bolts that were the wrong size.
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