NIST Report Finds Champlain Towers South Compression Started Weeks Before Final Collapse

The partial collapse of a Miami-area beachfront condominium in June 2021 actually began long before the building collapsed in June 2021, killing 98 people, according to a new investigation released this week. 

Why the building collapsed has been a bit of a puzzle, since there was no explosion, storm, or other obvious reason why the east and middle sections of the Champlain Towers South in Southside, Florida, should have fallen. Days after the disaster, members of the National Institute of Standards and Technology (NIST) National Construction Safety Team began investigating what caused the tragedy. They spent nearly five years analyzing the physical evidence and historical records, as well as conducting interviews, geotechnical studies, materials testing, and running simulations to identify a reason for the collapse.

“Based on this extensive work, we have concluded that the failure most likely began in early June (2021), about three weeks before the collapse, when two connections between garage columns and the pool deck slab failed,” said Judith Mitrani-Reiser, investigative co-lead and senior research scientist for NIST, in a video statement released with the report.

The failures of those two columns (also known as punching shear failures) resulted in cracks that grew during the next three weeks, with the loads redistributing and transferring to adjacent column connections that were not strong enough to support the weight.

This load redistribution caused the slab of the ground-level pool deck to sag further and eventually break away from the building, according to NIST. When the slab broke away, it damaged two connections supporting part of the tower, which resulted in the collapse of the middle and east parts of the building.

One of the reasons for the structural failure dated back to Champlain’s construction and design. The 136-unit, 13-story condominium building was built in 1981, but did not adhere to codes and standards for providing a margin against failure. Buildings that adhere to these standards are able to support much more load than what they are expected to bear, according to Mitrani-Reiser. 

“In the case of Champlain Towers South, these margins against failure were too narrow from the start,” she added.

Additional loads were added to the structure during the next 40 years. Instead of a storm, flood, explosion, or other obvious trigger, the final element that eroded “the critically low margins of safety to the point of failure was most likely long-term degradation from corrosion,” said Glenn Bell, investigative co-lead and research civil engineer for the National Construction Safety Team.  

The report, which was published almost exactly five years since the collapse, acknowledges that while there is not an absolute certainty about the path from the initial column failures to the fall, the investigators’ proposed scenario is consistent with the evidence. NIST previously published findings about its progress, as well as response and recovery efforts.

NIST investigators added that although the cause of the collapse has finally been identified, they will continue to create and hone recommendations to improve the structural safety of buildings to prevent similar incidents from occurring in the future.

Along with the nearly 100 people that died in the collapse, several others were left homeless. In 2022, a Miami-Dade circuit court approved a settlement of more than $1 billion to settle charges of negligence, wrongful death, and personal injury stemming from the collapse.

One of the defendants was the building’s contract security provider, Securitas Security Services USA, Inc., which was ordered to pay nearly half of the total settlement. Minutes prior to the collapse of the building, the pool deck caved into the underground parking garage. The Securitas security guard on duty immediately called 911 and reached out to residents via cell phones, but she did not use the building’s alert system, which was connected to intercoms in each unit. The guard, Shamoka Furman, later said that if she had known about the alarm system, she would have used it to alert residents of the danger. During the lawsuit, depositions revealed that the company’s security guards were not all trained to use the alert system that could have helped evacuate the building and save lives.