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.
The city council last month renewed the contract for the monitoring service, which will cost $29,000 for the year ending June 30.
The roof covering — the likely source of last weekend’s water dripping onto the basketball court — is deteriorated and needs to be replaced.
The city council in January approved a $55,500 contract with its architectural firm for design work on the re-roofing project.
That will involve removing layers of old roofing material, then installing insulation and a new roof covering made of an “elastomeric” material that will expand and contract with the building, Lewellyn said.
Besides needing a new covering, which officials say it will get as soon as possible, the arena’s roof is in good shape, Oklahoma City Public Works Director Eric Wenger said.
“We’re not seeing any major maintenance other than the re-roofing project,” Wenger said. “We’ve got a leak in the roof that we’re going to fix.”
Ward 6 Councilwoman Meg Salyer said she is confident the building is safe.
“I have every confidence in that,” she said. “They are so cautious about people being on that property.
“It’s a difficult roof,” she said.