Condo's structure scrutinized; death toll at 11

The focus in the deadly collapse of a condominium tower in South Florida shifted to the structural integrity of the building as an 11th fatality was reported Monday.

The collapse of the 40-year-old, 12-story Champlain Towers South in Surfside — an Atlantic Ocean coastal town of 5,700 about 15 miles north of Miami — happened around 1:30 am Thursday.

More than 150 people believed to be in the building at the time are missing.

"We're going to continue and work ceaselessly to exhaust every possible option in our search," Miami-Dade County Mayor Daniella Levine Cava told a news briefing Monday.

Morabito Consultants, a Maryland structural engineering that also has offices in Florida, said on Saturday that roof repairs were underway at the time of the collapse, but concrete restoration had not yet started.

In 2018, the firm released a report detailing deterioration of concrete in the underground parking garage as well as damage in a concrete slab beneath the pool deck. The report's author, Frank Morabito, wrote that the deterioration would "expand exponentially" if it were not repaired.

The cost of repairs was put at $9.1 million. The firm was rehired in June 2020 to prepare a restoration plan, according to The Baltimore Sun.

Ross Prieto, who was Surfside's top building official in 2018, met residents the month after the first report and assured them the building was "in very good shape", according to minutes of the meeting released by the town on Monday.

Prieto, who no longer works for Surfside, told The Miami Herald he did not remember getting the report.

Prieto now works for CAP Government Inc. CAP Government on Monday told officials in Doral, Florida, for which the company provides building inspection services, that Prieto is on leave, according to the city, CNN reported.

The engineer's report was commissioned before the condo sought recertification, required for buildings that reach 40 years old.

Miami-Dade Assistant Fire Chief Raide Jadallah said at a news conference that workers have found voids in the rubble large enough to keep victims alive.

"Not to say that we have seen anyone down there, but we've not gotten to the very bottom," he said.

He said searchers have heard some sounds, such as tapping or scratching, though he acknowledged it could be metal shifting.

"Every time there's an action, there's a reaction," he said. "It's not an issue of we could just attach a couple of cords to a concrete boulder and lift it and call it a day."

"We have been able to tunnel through the building," Andy Alvarez, a deputy incident commander with Miami-Dade Fire Rescue, told ABC's Good Morning America. "This is a frantic search to seek that hope, that miracle, to see who we can bring out of this building alive."

Alfredo Lopez, who lived with his wife in a sixth-floor corner apartment and got out, said he doubts anyone will be found alive.

"If you saw what I saw: nothingness. And then, you go over there and you see, like, all the rubble. How can somebody survive that?" Lopez told The Associated Press.

Michael Stratton was on the phone with his wife, Cassondra, who told him their building was shaking just before the collapse. She was looking out from a condo at Champlain Towers South when she told him she saw "a sinkhole where the pool out her window used to be", he told The Miami Herald.

The phone call then cut off, and she is among the missing.

Meanwhile, a commercial pool contractor who visited the building a week ago told the Herald that "there was standing water all over the parking garage". The contractor, who asked not to be named, told the newspaper he noted cracking concrete and severely corroded steel rebar under the pool.

The amount of water seemed so unusual that the contractor mentioned it to a building staff member who was showing him around, the Herald reported.

"The key element to this investigation, in my opinion, lies in that rubble, in those columns and condition of the structural elements," Sinisa Kolar, a Miami-based engineering executive told CNN.

The disaster most likely resulted from a combination of foundational and structural problems, said Mehrdad Sasani, a professor of civil and environmental engineering at Northeastern University.

The collapse likely started at lower floors of the condo and could have been influenced by "40 years of exposure to salt, water and salt air and the indication of some level of damage in the garage at the lower floors of the building", he told CNN.

A range of other factors could have contributed to foundation and structural failures, including vibrations from recent construction work, heavy equipment on the roof and water damage from the building's pool, Sasani said.

Greg Batista, a specialist in concrete repair projects, told CNN: "I've been up and down the coast (to) hundreds of buildings where you have concrete problems. If not maintained, whether it's a concrete problem or a settling problem — it could be a bridge, it could be a building, it could be a dam or a sea wall — these kind of things happen if not tended to."

Other possible contributing causes could be seismic loads from construction next door, which could degrade the structural capacity, as well as roof loading, Gregg Schlesinger, a Fort Lauderdale-based contractor, told CNN.

The building had numerous inspections as part of its 40-year certification, a process put in place after Hurricane Andrew in 1992.

The building's website (champlaintowerssurfside.com) lists how victims and families affected by the collapse can be helped.

The Associated Press and Reuters contributed to this story.