Wreckage hints at possible construction flaw

Engineers see inconsistencies with use of steel

Engineers who have visited or examined photos of the wreckage of the Champlain Towers South condominium complex in Surfside, Fla., have been struck by a possible flaw in its construction: Critical places near the base of the building appeared to use less steel reinforcement than called for in the project’s original design drawings.

The observation is the first detail to emerge pointing to a potential problem in the quality of construction of the condo tower that collapsed last month, killing at least 24 and leaving at least 124 still unaccounted for.

Reached by phone, Allyn Kilsheimer, a forensic engineering expert hired by the town of Surfside to investigate the collapse, said the investigation was still in its early stages. But he confirmed there were signs that the amount of steel used to connect concrete slabs below a parking deck to the building’s vertical columns might be less than what the project’s initial plans specified.

“The bars might not be arranged like the original drawings call for,” Kilsheimer said in an interview. He said he would need to inspect the rubble more closely to determine whether in fact the slabto-column connections contained less steel than expected.

R. Shankar Nair, a member of the National Academy of Engineering and former chair of the Council on Tall Buildings and Urban Habitat, was among the other engineers who reviewed photographs and saw inconsistencies between the design and the steel that remained visible in the columns.

The investigation of the collapse could take months, so preliminary observations and findings could change. Some engineers said the possible shortfall in steel rebar in the relatively small part of the building they had examined should not be seen as a cause of the collapse, but it could potentially have been one of several factors that allowed whatever initiated the problem to accelerate into a catastrophic failure.

In raising questions about the amount of steel reinforcement in the

building, engineers pointed to three damaged columns in a western section of the building that remains intact.

Those columns were part of an exterior deck that served as a groundlevel parking area adjacent to a pool plaza. It is a key point of interest, because at least two witnesses have said they saw part of the deck collapse in the minutes before the building toppled.

The tower’s 1979 design drawings, provided by the town and reviewed by structural engineers and The New York Times, indicate that the vertical columns in many parts of the building were supposed to provide a critical structural connection to horizontal slabs, embedded with eight rods of reinforcing steel near the tops of the slabs. But the reinforcing rods in the parking area appear to be

fewer in number.