In the aftermath of tragedies, like last year’s collapse of the Champlain Towers South condo complex in Surfside Florida, conversations inevitably shift to gleaning some lesson amid the sadness and chaos, a kernel of wisdom that will help to prevent something so horrific from happening again. Given the historic scope of the Surfside collapse, the analysis has been particularly extensive along with calls for systemic change.

But after a year of searching and studying, what have we learned – and can it keep us safe?

Abieyuwa Aghayere, PhD, a professor in Drexel University’s College of Engineering, has been hard at work since that tragic day last June trying to help the public understand what happened. During the days and months following the collapse, Aghayere shared his insight as a structural engineer with reporters trying to find answers. His contributions were included in thousands of stories over the past year, including the coverage that earned a team of reporters at the Miami Herald a Pulitzer Prize.

And in recognition of his thought leadership in the aftermath, he has been an invited keynote speaker at the 2022 Annual Convention of the Structural Engineers Association of California (SEAOC), and delivered a special invited seminar to the National Institute of Standards and Technology (NIST)’s National Construction Safety Team — the federal agency charged with investigating the collapse. He is also an invited panelist in a session at the Smart Cities Connect Fall Conference & Expo later this month.

Aghayere recently took time to share what he’s learned in this past year of studying and thinking about the collapse and what it means for the future of our built environment.

The typical factors that contribute to structural collapses include: design errors, construction errors (e.g. poor workmanship, use of deleterious materials); lack of adequate maintenance, foundation failure; extreme loading (e.g. blast, terrorism, or subjecting a structure to a higher load than it was designed for); external factors, such as adjacent construction vibrations and dewatering or lowering of the water table; and environmental factors, such as seawater infiltration and the presence of salt air moisture.

My discussions with fellow structural engineers have converged on the idea that many of these factors banded together to arrive at this tragic “perfect storm” that was the Champlain Towers South collapse. Many tell-tale signs of serious problems were ignored, even as the building was crying out for help in many ways, such as through cracking and spalling and water leakage.

Yes, Florida enacted a law in May 2022 for buildings three stories or higher, with the following requirements:

A few states and cities already had some periodic inspection regulations in place before the Champlain Tower South collapse for certain structures and structural elements, such as bridges (at least every two years), parking garages, balconies and facades. Some examples of inspection frequencies for structural elements are shown in the table below:

Note that countries, such as Singapore and Malaysia, have had periodic inspection regulations in place for entire building structures for decades – at least since 1989, in the case of Singapore. The International Code Council (ICC) has some work in progress with regards to the time intervals for maintenance inspections (occurs annually), periodic inspections, and milestone inspections of buildings, as a function of the risk category of the building and exposure to environmental factors. For example, hospitals, which have a higher risk category than an office or residential building, could have periodic inspections every five years and milestone inspections every 20 years, compared to every 10 years and every 20 years, respectively, for office or residential buildings.

What I have noticed is increased activity within building departments — especially in Florida — to get older buildings inspected and reviewed well before the 40-year mark, which used to be the threshold age for recertification review. Some condominium buildings have been evacuated in Florida — and one in South Carolina — due to structural deficiencies. Structural engineers reviewing a condominium building in Florida recently called for evacuation of the building due to excessive deflections and post shoring of the underground parking garage “roof” slab was provided in another condominium building. So, I have noticed that structural engineers have not hesitated to act when they have noticed problems.

There are a number of existing inspection techniques (e.g., impact echo, ground penetrating radar – GPR) that if used in the Champlain Towers South condominium could have provided information about the internal condition of the concrete in the slabs and columns, and the rebar within. I suspect we will see an increased use of these technologies going forward.

Repair the structurally deficient elements in bridges with ratings of 4 or lower. Shore up and retrofit these bridges and replace any lost section due to corrosion to prevent sudden and brittle-type collapse like what happened in Pittsburgh. The Fern Hollow Bridge in Pittsburgh was built in 1970 with a rigid steel K-frame superstructure system and had a September 2021 inspection rating of “poor,” or 4. It collapsed in January 2022, and apparently, no repair or retrofitting work had been done on the bridge since the September 2021 “poor” rating.

Many such bridges with “poor” ratings should be replaced, but they remain in service because of lack of adequate funding for bridge maintenance, repair, and replacement. There are more than 3,000 bridges rated in “poor” or structural deficient condition in Pennsylvania out of about 25,000 state-owned highway bridges.

Repair or replace all bridges with ratings of 4 (i.e., a “poor” rating) or lower. Rather than relying on just visual inspection which occurs at fairly long intervals (e.g., two years for bridges), use remote monitoring technology, such as accelerometers and fiber optic sensor networks, to continuously measure and monitor critical structural parameters, including frequency and amplitude of vibration and displacements, in buildings and bridges with the help of a data acquisition system and data analysis software.

The data obtained can be translated into structural parameters, which can be used as an early warning alert system of any imminent structural problems if certain thresholds are exceeded, just like the data from the sensors in airplanes. The use of such technology, in bridges for example, will create a database of structural parameters that can be helpful to bridge owners in prioritizing the repair and maintenance of their bridges.

There are usually not enough financial resources to repair or replace all structurally deficient bridges, but with the recent infrastructure funding, hopefully the repair and replacement of more bridges will become possible.

In general, the municipal building departments in smaller jurisdictions, like the town of Surfside, should either employ competent and licensed structural engineers to review the drawings that are submitted for building or construction permits. If they cannot afford this, they should contract out the reviews to private structural engineering firms.

In the case of Champlain Towers South, I would have expected the Building Department review of the structural drawings to have detected the glaring design errors pertaining to the concrete cover to the rebar in the exposed concrete slabs and the congested or overcrowded vertical rebar in the concrete columns in the East Tower. Those design errors should have been easily identified.

More specifically, here are a few suggestions based on lessons we learned from the Champlain Towers South collapse, that could help to prevent similar tragedies in the future:

Media interested in talking to Aghayere should contact Britt Faulstick, interim director of media relations, at bef29@drexel.edu or 215.895.2617.

Britt is the assistant director of media relations who covers primarily technology and engineering beats, including information and computer science. He also covers a number of areas in media arts and design, student life, research ventures, athletics and more. Britt is a graduate of Syracuse University’s S.I. Newhouse School of Public Communications, in his senior year the Orange won the men’s basketball national championship. He worked in Drexel’s athletics department for seven years, during this time the women’s basketball team won its first conference championship. So if history is any indication, the media relations team is due for a big win. Follow him at @DrexelBritt or view his blog posts here. Contact Britt at britt.faulstick@drexel.edu or 215.895.2617.

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