The tragic collapse of a 12-story oceanfront condominium last week in a tiny hamlet within the same big island as Miami Beach, Fla., has structural engineers and designers worried about future construction disasters.
Experts believe such unexpected failures are uncommon in the contemporary history of structural design. Engineers and planners, on the other hand, are eager to understand what caused the Champlain Towers South in Surfside, Fla., to collapse on June 24. There have been 16 confirmed deaths so far, with more than 140 individuals still missing. There has been no immediate explanation for the catastrophe. Structure damage and probable corrosion of the reinforced concrete building’s base or stabilizing rebar have been hypothesized by experts.
Structural engineers strive to create structures that can endure the forces and dangers of gravity and the elements. Engineers change design approaches regularly, typically in reaction to technological advancements or hard-won lessons learned from failures. However, virtually all of the building stock in the United States is not brand new. For example, Champlain Towers South was built in 1981. These structures may be subjected to stresses and other dangers that the developers did not anticipate, such as those associated with climate change.
Structural engineers, leaders, and policymakers may have to wait until the completion of rescue efforts and, most likely, numerous investigations into what caused the Surfside fall for helpful insights into how to change designs and construction rules to prevent future disasters.
What is the reaction of structural engineers to the collapse of Champlain Towers South?
Buildings don’t fail very often, and the field takes the need to learn when they do, especially when the failure isn’t caused by some clear, huge, external triggering event that we didn’t plan for. The Kemper Arena roof collapse and the Hyatt Regency Hotel walkway collapse, both in Kansas City, Mo., in the late 1970s and early 1980s, prompted the field to reassess its design methods and led to advancements in construction and how we use computerized structural analysis.
When earthquakes strike, we have a history of attempting to figure out what went wrong and then altering our field accordingly. What’s alarming about this recent failure in Florida is that even early speculations about what went wrong provide us with little indication about what we need to do differently. If this is simply a corrosion problem, the number of structures with corrosion problems in the United States is staggering. If this is a foundation problem, we may be able to figure out the root reason and go from there. Several unknowns may not have been considered when the design of Champlain Towers South was finished in 1981.
Is it probable that the building’s columns, rebar, or reinforced concrete will be thoroughly checked for potential corrosion?
Definitely 100 %. This is an older concrete structure that has been exposed to sea salt and has experienced a lot of floods. Too much rust will eventually bring a structure down. But you’re still perplexed: “Why now?” “What brings you here today?” Corrosion is a slow and painful process. Of course, there will be a point at which it will have gone too far. “Is there another triggering factor?” one may question.
How important will the rescue, recovery, and any follow-up actions at this location likely be?
This volume of debris would be a significant, multi-month problem in and of itself if it weren’t for the human tragedy. So, even if you don’t try to figure out why the project failed, just trying to get back to square one is a difficult task.
Could we expect an increase in the number and severity of occurrences like the Surfside building collapse as the US building stock ages?
We can’t afford to disregard our infrastructure and must invest in it. For the past 40 years, experts have been telling us this. Last month, a massive fracture in a beam forced the closure of a key bridge between Memphis, Tenn., and Little Rock, Ark., on Interstate 40. These kinds of situations are only going to become more common. They won’t all be caused by our failure to maintain our infrastructure, but many wills. Climate change isn’t helping matters. Our infrastructure is mostly in place and established, but we must continue to invest in its development.
We’re also in uncharted terrain in terms of seeing requirements on buildings that we didn’t anticipate, whether it’s a climate-change-induced requirement for flooding once a year where we wouldn’t have expected any or more regular higher-speed windstorms. Buildings are a part of the environment in which we live. We create them with that atmosphere in mind.
But what do you do when a region that has never had heavy snowfall has a storm in the South similar to one that occurs in Boston one winter? We build roofs based on historical snowfall data, but those once-in-a-lifetime occurrences are no longer so unusual. We have more powerful hurricanes. We are experiencing prolonged heatwaves. Keeping up with those shifting needs is a challenge for us as structural engineers.
Gravity is still gravity at the end of the day. These days, we can become a lot more specific when it comes to understanding the fundamental forces that act on a structure. And, unlike previous decades, we can now pinpoint exactly what happens when something starts to fail. However, accurate demand forecasts are required.
What events and failures in the past have led to modifications in building designs in the current era?
Many of them were caused by earthquakes. The earthquake in Northridge, California, in 1994 altered a lot of people’s minds about how we construct buildings in earthquake-prone locations in the United States and across the world. In 1968, a resident’s gas heater exploded, destroying 22 stories of the Ronan Point building in [England], killing four individuals. That incident ushered in the rising awareness of the dangers of building collapses. The Grenfell Tower fire in London in 2017 spread from the building’s façade through the whole structure. This has a significant influence on the kind of facades that should be permitted. And I believe that’s why there’s so much interest in this specific collapse in Surfside, Fla. because we don’t yet know what happened.
How are large-scale building collapse investigations like this one carried out?
Investigators will compile all of the original design’s computations and drawings. They may then compare those to final construction documents, as well as any alterations that may have occurred along the route. They will then analyze the building’s actual condition at the time of the collapse. This might include obtaining samples of the building rubble and conducting tests to assess the concrete and rebar’s pre-collapse strength. There has been a lot of conjecture regarding the condition of the columns at the foot of the Champlain Towers South building, so they’ll do all they can to figure out what they were like when they first arrived, as well as the extent of corrosion and degradation.
Investigators will most likely perform a current computer simulation on the structure to evaluate how well it holds up to the demands placed on it in comparison to the codes in place at the time of design. But, more significantly, they’ll compare the structure to existing building regulations to see what kind of performance we might anticipate today.
When evaluated through a modern viewpoint, this will provide an early indication of whether the structure had any unexpected or major design error that contributed to its near-failure. Then, using all of the evidence they’ve gathered, they’ll come up with probable scenarios that they believe are compatible with the failure. Then they’ll try to mimic and understand whether or not certain scenarios are likely, which might include some testing.
Are certain cities on their way to becoming like New York 2140, as described in Kim Stanley Robinson’s novel? Residents in post-climate-disaster Manhattan, N.Y., dwell in skyscrapers with massively waterproofed foundations and travel by watercraft in a perpetually flooded street grid, according to that science-fiction novel.
He proposes a degree of adaptation in which we can maintain all of our building infrastructures and simply cover the bottom of it with some extension of the present technology for mending concrete that has been exposed to chronic saltwater. That’s probably a stretch. Our infrastructure is largely underground. It is impossible to use underground infrastructure that has become underwater infrastructure. People will not dwell in a structure that lacks power, water, or sewer supply.
In the lifetimes of today’s structural engineers, a significant amount of building and infrastructure adaption will occur. At least some high-wealth regions will be flooded and subsequently relocated because they have the financial means to do so. The question is how we will deal with the unfairness of mass migration away from our population centers, which already have a significant imbalance.