UC Berkeley structural engineering professor analyzes collapse of Miami-area condo

BERKELEY, Calif. - Images of the collapsed condominium building in Florida show how the floors of the 12-story building fell in a stack about 1:30 a.m. Tuesday as many of the residents inside were sleeping. 

The search for the remaining 100-plus missing people continued through the night, as families waited and hoped crews would find more survivors. By Friday, at least four people were declared dead.

The collapse has raised questions about how such a structural failure could have happened.

UC Berkeley Professor Khalid Mosalam is an expert in structural engineering and says there were two things that came to mind when he saw video of the building.

"We have this pancake-like collapse, and this can only happen if these floors are not well connected to the actual core of the structure. I see a lot of rebars sticking out. They seem not to be very long so it means there may not have had enough overlap with the existing rebars in the slabs," he said. "Looks like there may be also corrosion issues."

The beachfront condominium was built in 1981 and officials say it was in the process of undergoing Miami-Dade County's mandatory 40-year recertification and safety inspection process.

"Forty years...could be too long to catch any deficiencies," said Professor Mosalam, adding that modern technology could help detect structural problems before a collapse, "In an earthquake country like in California, there are sensors that we put in buildings and on bridges, which they can monitor the vibration of buildings or bridges for that kind of hazard.

"With aging infrastructure," Mosalam added, "That would be wise to do something like that and have a monitoring program, at least for the older type of construction."

The Surfside mayor says there was work being done on the building's roof and construction was also reportedly going on nearby.

"In the photos, you see several columns fail, and that's what triggered the failure of the multiple floors. It means they have experienced loading that's higher than their capacity. And that's typically caused by excessive load, maybe on the roof, or from the ground. Excessive vibration...that can lead to compromising the soil or creating sinkholes...which basically is pulling the soil underneath the foundation," said Mosalam.

For the families, there is hope, however slim, that crews might still find survivors.

Rescue crews managed to pull out a boy Tuesday morning, who was among the dozens of survivors who were found.

Crews rescued one mother but had to amputate her leg to free her from the debris.

"It's a difficult job, a tough job, a dangerous job," said Senator Marco Rubio who praised the first responders.

"The humanity, the evidence of people living their daily lives and that everything, everything evaporated in an instant," said Congresswoman Debbie Wasserman-Schulz, "This is a tragedy without precedent in the United States of America. The devastation that I witnessed today is the likes of which I've never seen."

Rescue crews brought in canine units to help with search efforts. Teams also worked from an underground garage to access tight spots.

"Every time there's a shift in the rubble, we have additional rubble that shifts on us," said Assistant Fire Chief Ray Jadallah, with Miami-Dade Fire Rescue who was serving as Chief of Operations.

Crews also used sonar equipment to help locate any residents.

President Biden declared a state of emergency in Florida, promising to send federal resources to help local governments and families.