Extensive Review of Champlain Towers Collapse Completed

also scanned many of the individual specimens using handheld 3D imaging technology to create more accurate 3D representations that could be analyzed further on a computer.

With the evidence secure, cataloged and accessible, NIST’s team members began extracting 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 carefully studied the cement and aggregate making up the concrete, and how it had aged. They also measured how water moves through the concrete. This movement depends on how the cement was formulated and impacts the potential corrosion of the reinforcing steel within it. Tension tests of the steel reinforcing bars helped determine the strength and deformability properties of the bars, and the impacts of corrosion. Learn more about NIST’s testing.

Despite extensive searching and inquiries, NIST has not been able to locate as-built drawings for Champlain Towers South. The team has therefore relied on the physical evidence to provide insight into how the building was constructed. 

An added challenge that has made the physical evidence so important is the lack of video showing exactly what happened. Champlain Towers South had approximately 24 functional security cameras at the time of the collapse that were recording to a digital video recorder (DVR) within the building.  

NCST members hoped to find the security camera DVR hard drive among the evidence collected, which had been sorted by the MDPD into “bulky” and “fine” materials. They conducted multiple searches of the bulky material from the collapse site using drones, personnel on the ground, aerial lifts, and powerful cameras. Unfortunately, no DVR devices were found in the bulky materials. The MDPD and NIST did identify a total of 25 hard drives among the fine materials. The NIST team analyzed these drives to determine whether any of them could have come from a DVR. Experts ultimately determined that the damage to the magnetic media was too extensive and that none of the drives were recoverable.

What the Testing Revealed
Corrosion in reinforcing steel is expected, but it can become an issue