Incident Description

Wind storm damage was reported to have occurred at buildings [C] and [B] of a large industrial facility that consisted of three adjoined buildings and was under construction at the time of the incident. The loss was estimated to be over one million dollars. Origin and Cause Inc. was retained to investigate and determine the cause of the collapse.

Investigation

A detailed visual examination of the affected buildings was carried out and design drawings were thoroughly reviewed. All available reports and witness statements were reviewed. The adequacy of the temporary bracing between the steel frames was evaluated via a detailed structural analysis informed with Environment Canada weather data for wind gust on the day of the event and by the established industry requirements for the design of temporary shoring during construction.

Cause of Loss

Origin and Cause Inc. determined that the temporary X-bracing between the columns of the steel frames along gridlines “D” and “F” using wire ropes was grossly insufficient to provide adequate lateral resistance to wind loads during construction. The cross-sectional area of the temporary steel wire ropes used were found to be less than 1/3 of the cross-sectional area required by design. This significant difference in the cross-sectional area made it highly unlikely that the temporary wire ropes could have had a resistance anywhere near that of the loads exerted by the wind gusts on the day of the collapse incident.