Bolt welds may have caused Midtown parking deck collapse

The company that managed the Centergy parking deck in Midtown believes it may know what caused the partial collapse that totaled 45 cars last month.

Whether it was a flaw in design or in construction remains to be seen.

In a letter to former patrons, David Tyndall — head of Gateway Development, which leased the deck — said secondary bolts welded to support an exterior beam on the fifth level of the structure failed to hold.

“For reasons now being studied, these connections did not adequately restrict one of the 5th level spandrel beams,” Tyndall wrote. A spandrel beam is an exterior beam that extends from column to column and marks the floor level between stories.

“Apparently” he continued, “as a result of the energy from vehicles transmitted along the planks, this particular spandrel member moved out away from the column it was resting on, thereby allowing first one and then the rest of the planks it was holding on the 5th level to fall.”

Those planks overwhelmed the design loads on the levels below, causing the deck to pancake, Tyndall wrote. Amazingly no one was injured during the midday collapse.

The findings are preliminary, as several independent firms continue to investigate.

“The question remains: what happened to precipitate the failure on this particular day?” said Steven Smith of Illinois-based CTL group, which examines collapses.

The incident is viewed as an anomaly by experts, as garages tend to collapse either during construction, within their first year or many years later, when time begins taking a toll. The Centergy deck, on 5th and Spring Streets, was completed a little less than five years ago.

“What we don’t know is whether it took this long for the flaw to develop or was it something else,” Smith said. “There’s the possibility that it was designed and erected properly.”

That’s unlikely, but Smith said it’s too early to direct blame.

“We have reviewed the information that has been provided to the Centergy garage patrons and, as stated in that communication, the investigation is still ongoing and a determination to the cause of the partial collapse has not yet been made,” said Bill Pinto, president of Hardin Construction Company, the lead contractor on the project, “Based on information available at this time it would be premature for us to speculate as to the cause of the partial collapse.”

Meanwhile, Gateway Development on Friday offered customers who lost their cars in the collapse six-month, no-interest loans of up to $500 to cover vehicle expenses. The company is also reducing parking rates for affected customers at its other location and waiving parking space charges for July.

A shuttle service is running between the Centergy building in Technology Square and the nearby AT&T parking deck on West Peachtree Street, a spokesman for Lanier Parking, Inc. said.

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