The Jim Norick Arena’s roof is a unique design that has had its share of problems in recent years.
On July 27, 2010, a concrete section of the roof fell in, landing in an unoccupied seating area, according to a city manager’s memo dated Dec. 7, 2010.
An investigation found that a part called a “roof tendon coupler” had failed because of corrosion, the memo stated.
Nobody was hurt, but the incident led to stepped-up monitoring of the roof’s condition once repairs were completed.
When it opened in 1965, the arena was described in The Oklahoman as the “largest coliseum-type structure in the Southwest constructed with the longest catenary roof span in the world.”
Jim Lewellyn, an engineer and manager in the city’s public works department, said Wednesday that the roof forms a bowl — hence the term catenary — atop the arena.
Steel cables, or tendons, in a grid pattern support concrete roof panels. A “compression ring” around the oval roof’s edge lends strength.
“Think of a tennis racket,” Lewellyn said.
According to the 2010 memo, the roof was a specialized design that is no longer in use. Lewellyn said he knew of three buildings that used the design and said Oklahoma City’s arena is the only one left.
In response to the 2010 incident, the city had what’s known as an acoustic monitoring system installed on the underside of the roof.
A network of 56 sensors “listens” for the sound that occurs when strands in the steel cables snap.