New findings emerge from investigation into Surfside condo building collapse

(CNN) — Federal investigators on Thursday shared updates on their investigation into the cause of a 2021 condominium collapse in Surfside, Florida, providing key information about the factors that could have killed 98 people under a mountain of debris.

Researchers identified hundreds of potential flaws in the building, ultimately narrowing down to about two dozen hypotheses about what might have caused the collapse, National Institute of Standards and Technology officials said in a presentation on their progress.

An investigation revealed that the building’s pool deck, located at ground level above an underground parking garage, collapsed at least four minutes before the rest of the building, confirming earlier witness reports. Possible structural failure in the pool deck or in the columns supporting the tower are among the main issues now being analyzed as teams investigate the cause of the disaster, investigators said.

A portion of the Champlain Towers South building collapsed in the early morning hours of June 24, 2021, turning what was once a prosperous residential building into a scene of destruction, crushing or trapping residents under the huge pile of metal. Twisted and concrete.

It took nearly a month for search and recovery teams to locate and identify the 98 victims, whose ages ranged from 1 to 92 years. The tragedy affected families around the world, including those in Argentina, Paraguay and Colombia. In some cases, entire families died.

This tragedy must have been decades in the making. Investigators have determined that the integrity of the Champlain Towers was compromised when it was being built in the 1970s, noting that the design and construction of some parts of it did not meet standard building code requirements at the time.

But the search for answers is still far from over, as researchers must continue to scrutinize the evidence and rule out a long list of possible scenarios. Its final findings are expected to be published in a report next year.

The agency investigates major building failures and disasters, including the World Trade Center on 9/11, but does not determine criminal charges. Instead, it can recommend changes to building codes to improve future safety standards.

CNN has sought comment from Surfside city officials.

These are the key takeaways from Thursday’s research update.

Investigators say parts of the original building were not up to code

When Champlain Towers was completed in 1981, parts of its structural design did not meet building code requirements, particularly in the pool deck and tower columns, investigators said in their filing.

“We found several locations where the construction did not meet the requirements of plans, building codes or general practice,” said James Harris, one of the project leaders.

According to the presentation, deficiencies were found in the building’s steel reinforcement, concrete placement and column and floor concrete strength. Officials noted that some areas of the pool deck had “severe” strength deficiencies.

In the months leading up to the collapse, structural repairs to the building were also underway. Condo association president Gene Wodnicki outlined some of the problems in an April 2021 letter to homeowners, noting that “deterioration of concrete is accelerating.”

At the time of the collapse, the condo association approved an appraisal detailing $15 million worth of repairs, a process they began more than two years after receiving reports of “major structural damage” to the building, CNN reports.

The pool deck sinks minutes before the building collapses

Before the chaos erupted, one resident reported being woken by a family member concerned about “metallic noises” coming from the building, and moments later saw the pool deck fall onto an underground garage. said Emel Ganapathy, who co-led efforts to gather evidence for the investigation.

According to investigators, the slab tower supporting the pool deck collapsed more than four minutes before the collapse. The connection between the slab and its support columns may have failed, causing the slab to fall into the garage, they said.

“There were signs of serious damage to the pool deck at least three weeks prior to the collapse,” investigators said in a presentation.

Prior to the incident residents reported hearing “banging” and “hammering” sounds indicating that the slab reinforcement had fractured, he said. The evidence also revealed that the slab was cracked, exposed to water and corroded in some areas.

Over time, the plants adorning the pool deck were also loaded with more fill and paving than originally designed, increasing the weight load on the slab, according to the release.

Together, all these flaws created a “seriously low margin against failure” at the time of the collapse, he said.

Still, the researchers noted, “while there is strong evidence that the collapse started at the pool deck, we have not yet ruled out failure initiation somewhere in the tower” that may have preceded the pool collapse. Pool deck.

Failure of tower columns is also a possibility

Investigators said they identified several scenarios in which the columns supporting the southern edge of the tower could have failed, forcing their load to be distributed elsewhere leading to the collapse.

Signs of the impending disaster can be seen in video footage that shows “severe structural movement” in the tower before the collapse, and according to researchers, rumblings and booms are heard in one of the upstairs hallways before the floor begins to sink and deform.

The initial structural failure that caused the eastern portion of the collapse was likely below the third floor, investigators said, adding that video footage showed the facade of the building moving “steadily downward” during the collapse.

Tower columns can be compromised in a number of ways, including corrosion, exposure to water and poor installation, the release noted.

There are still dozens of hypotheses

Although the researchers said they identified strong evidence supporting possible causes of the collapse, they did not rule out dozens of other hypotheses through extensive analysis and testing of the evidence.

Other possible, but less likely, causes include foundations being laid unevenly or being built on topography that develops sinkholes or other vulnerabilities, officials said.

Once the investigation is complete, the National Institute of Standards and Technology plans to publish a multi-volume final report on its findings, as well as a public-friendly online presentation by fall 2025.

“There are millions of high-rise condominium units in Florida alone; many of them are older structures near the ocean,” their website says. “While the NIST investigation aims to identify the cause of the Champlain Towers South collapse, it may also uncover potential problems at other similar buildings nearby and across the country.”

The report may also provide much-needed answers to victims’ families, who have seen important protection legislation and legal settlements, but have waited years for an explanation as to why the tragedy happened in the first place.

CNN’s Jameel Lynch, Nouran Salahih and Joe Sutton contributed to this report.