Investigators are closing in on determining the technical cause of the collapse of Champlain Towers South, a 12-floor beachfront condominium in Surfside, Fla., in the early-morning hours of June 24, 2021.
However, a final report on the tragic collapse is still more than a year away.
The National Institute of Standards and Technology (NIST) has completed its extensive review, measurement and testing of critical building evidence extracted from the collapse site.
More technical work will be completed this year. The entire investigative team has already begun drafting its findings and recommendations, with a draft report planned for spring 2026.
With the review of the evidence now completed, it has been returned to the custody of the Miami-Dade Police Department (MDPD).
“Our team members were in Surfside within 48 hours of the partial collapse of Champlain Towers South, working in collaboration with the Miami-Dade Police Department and others to help ensure the identification and preservation of potential evidence that could explain the collapse,” investigative lead Judith Mitrani-Reiser said in a written statement released recently.
“Since then, we have conducted extensive testing of concrete slabs, columns and reinforcing steel so that we could understand the condition of the building and the forces acting on it at the time of the tragedy.”
The ultimate goal of the NIST investigation is to establish the likely technical cause or causes of the building failure and, if appropriate, recommend specific improvements to building standards, codes and practices.
The investigation has been complicated by the fact investigators had to take care not to interfere with search and rescue operations that were ongoing shortly after the collapse.
Procedures for preserving potential evidence were developed in co-operation with the Miami-Dade Homicide Bureau, the Miami-Dade Fire Department, structures specialists with the urban search and rescue task forces, and the many contractors working on the site.
“The collaboration, co-ordination and co-operation with everyone onsite was key to ensuring we would have the evidence needed to understand what caused this tragedy,” said investigation associate lead Glenn Bell. “We were able to obtain over 600 pieces from the site that have provided valuable insight into Champlain Towers South.”
The NIST was provided access to the evidence while it was in MDPD custody and when it was moved to various locations.
Investigators extracted samples of concrete and steel reinforcing bars for testing to learn everything they could about how the building was built, how its materials and construction may have deviated from its original design, how its components had aged, and if any changes had been made to the structure over its 40-year life.
The concrete testing included compression and tension tests that revealed how well the samples would hold up to pushing and pulling forces. Researchers studied the cement and aggregate making up the concrete, and how it had aged. They also measured how water moved through the concrete as it would impact the potential corrosion of the reinforcing steel.
Tension tests of the steel reinforcing bars helped determine the strength and deformability properties and the impacts of corrosion.
Despite extensive searching and inquiries, the NIST was not able to locate as-built drawings for Champlain Towers South and therefore relied on the physical evidence into how the building was constructed.
There was also no video to show what happened. Although the building had 24 functional security cameras that were recording to a digital video recorder within the building at the time of the collapse, investigators were unable to find the hard drive.
Investigators tested reinforcing steel from the debris to document the degree of corrosion at the time of the collapse and reverse engineered materials in the concrete mixture used in the original construction to quantify the degree of aging and deterioration of the samples. They also recreated the concrete from the building and used it to build large-scale replicas to enable labs at the University of Washington and University of Minnesota to test them for failure.
Recovered evidence revealed various ways in which the building’s materials had changed or been changed over time. This included cracking and spalling and how the addition of new materials and finishes, landscaping vegetation and water leakage may have affected the structure.
“To be confident we have determined the most likely cause or causes of this terrible tragedy amongst the many possibilities, we are collecting and analyzing all the evidence we can for and against each hypothesis,” said Bell. “We are leaving no stone unturned.”
Technical work still to be completed includes analyzing how well the building’s construction matched the requirements of the original design drawings, analyzing whether soil or foundation issues contributed to the failure, and looking at the distribution of material properties throughout the structure, and the degree and causes of corrosion of steel reinforcement.
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