Video of building indicates corrosion

MIAMI — Video released by a team of federal investigators shows more evidence of extensive corrosion and overcrowded concrete reinforcement in a Miami-area condominium that collapsed in June, killing 98 people.

The National Institute of Standards and Technology also announced Wednesday that it will conduct a five-pronged investigation into the Champlain Towers South collapse, which will be led by Judith Mitrani-Reiser, an engineer who grew up in Miami.

“We are going into this with an open mind and will examine all hypotheses that might explain what caused this collapse,” Mitrani-Reiser said. “Having a team with experience across a variety of disciplines, including structural and geotechnical engineering, materials, evidence collection, modeling and more, will ensure a thorough investigation.”

The video shows densely packed steel reinforcement in various sections of the building, along with corrosion where one column met the building’s foundation.

“The corrosion on the bottom of that column is astronomical,” Dawn Lehman, a professor of structural engineering at the University of Washington, told the Miami Herald. She said that amount of corrosion should have been obvious and documented as part of the 40-year inspection that was ongoing when the building in Surfside, Fla., collapsed June 24.

The images show beams, walls and columns that appear to be overcrowded with steel reinforcement, which suggests potential weaknesses, she explained.

The risk posed by “congested” vertical rebar in columns would have been even worse in spots where the rebar overlapped, which is known as “lap splice” regions, Abieyuwa Aghayere, a Drexel University engineering researcher, said.

He said he was struck by how “powdery” and white the concrete in columns appeared in the newly released video. Stonelike aggregates used to strengthen concrete during construction typically remain visible, but they were not in the images from the collapse site.

“The white color just stuns me,” Aghayere said. He added that instead of seeing aggregate material mixed into the concrete, “it’s just homogeneous,” which is likely an indication of saltwater damage.

“It doesn’t look like normal concrete to me,” Aghayere said.