Paul Zilio, a senior principal with Miami-based structural engineering firm Bliss & Nyitray, was not involved in the design of the building but said Miami’s structural engineers have spent a lot of time in the last day discussing what might have happened.
He said that while a thorough forensics evaluation is ongoing, a few things could have contributed to the collapse.
The building had recently undergone roof work, but that extra weight would unlikely to be the cause. “Even if the roof collapsed, I don’t believe the next floor would have collapsed,” Zilio said.
He said the building settling, documented in the 1990s to be 2 millimeters (0.08 inches) per year, could have contributed to failure “because if that continued for the 40-year life of the building, the total of over three inches of settlement could certainly contribute to the collapse.”
Ocean sea spray is also a danger, Zilio said: “Over time the saltwater can penetrate the concrete and corrode the reinforcing steel, causing the reinforcing steel to expand. This expansion cracks the concrete and eventually chunks of concrete spall off, weakening the capacity and making the reinforcing steel even more exposed to corrosion.”
He said garages are particularly vulnerable to sea spray: “If you look at the outside of this condo building, the stucco and waterproofing protect the structural elements. But the lower level parking garage is exposed to moisture from rain, humidity, cars driving by, and especially sea spray due to the building being on the beach.”