The Collapse of Champlain Towers South

  

Champlain Towers South collapse (photo by the Miami-Dade Fire Rescue Department. The original uploader was TheEpicGhosty at English Wikipedia., Public domain, via Wikimedia Commons)

The news of a building-related tragedy never fails to command my attention. Such was the case when I learned of last Thursday’s partial collapse of Champlain Towers South, a 12-story, 136-unit beachfront condominium building in the Miami suburb of Surfside, Florida.

My first thought upon seeing images in the immediate aftermath of the event was for the victims. Given the disaster occurred at 1:30 AM when most residents may have been in their beds sleeping, surely many were killed or trapped within the rubble. As of this writing, authorities have confirmed nine deaths, eleven injuries among 37 rescued individuals, and as many as 156 people who remain unaccounted for. Urgent rescue operations continue.

My second thought was to ask why this happened. The possibility of an act of terrorism crossed my mind, so much did photos of the calamity remind me of the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City. News accounts quickly dispelled that notion: There was no bomb or explosion. Clearly, the Champlain Towers South building suffered a massive, cascading structural failure. What caused it to happen? Something so catastrophic does not occur without a reason.

There was some initial speculation suggesting the culprit may have been a growing sinkhole beneath the tower’s foundations. Indeed, analysis by Florida International University revealed the building had been sinking since the 1980s at a rate of 2 millimeters per year. This is a significant amount; however, other nearby locations (such as on artificial islands in Biscayne Bay) indicated rates of sinking as much as 3.8 millimeters per year without a similar occurrence (yet). We could attribute the steady sinking to solution-type or cover-subsidence sinkholes, which form gradually, but investigators quickly shifted their attention to previously observed deficiencies in the building’s design and construction.

For an architect like me, this is where the story becomes especially consequential and germane to the work I do. To what extent are the original architects and engineers culpable for the structural failure of Champlain Towers South? Was there something inherent in the building’s design and detailing that ultimately led to its collapse? What about the quality of its construction? Was shoddy workmanship to blame? And how much can we attribute to the condominium association’s failure to respond in a timely and responsible manner to oversee necessary building maintenance and repairs?

A structural engineering report and field survey conducted by Morabito Consultants in 2018 identified serious water infiltration problems in the building, some of which had resulted in subsurface deterioration of the concrete structure. Failed waterproofing caused major damage to the concrete slab below the pool deck and entrance drive. Morabito recommended immediate (and costly) replacement of the waterproofing system to prevent concrete weakening from expanding “exponentially.” Evidence of the damage water infiltration was doing to the concrete—such as extensive spalling (sometimes exposing the rebar) and cracking—was readily visible in the columns, beams, and walls before the building’s collapse. The condominium association’s failure to promptly address the obvious need for repairs and remediation of the water infiltration was clearly a factor contributing to the devastating structural failure.

The choice of reinforced concrete for much of the building’s structure and exterior finish may fundamentally be cause for blame as well. Water entering through tiny cracks creates an electrochemical reaction, which powers the conversion of reinforcing steel to rust. Rust is flaky and friable, affording no protection to the underlying metal, unlike the formation of patina on copper surfaces. Rust causes the rebar to expand, enlarging cracks and forcing the concrete to fracture apart (spall). In the case of the Champlain Towers South building, it didn’t help that coastal Florida’s hurricanes, storm surges, and the corrosive salty air readily exploit concrete’s weaknesses.

Of course, the use of reinforced concrete exposed to the elements is far from uncommon. The architectural expression of raw, unfinished concrete gained favor among designers during the 20th century, especially during the 1950s-1970s heyday of Brutalism. The abundant legacy of that period is all around us today, and much of that legacy is literally crumbling. It’s natural to think of concrete as being durable, and of using the material in construction as “building for the ages.” After all, the 1,900-years-old Pantheon in Rome is in excellent condition, right? The difference is the Pantheon’s concrete does not rely upon steel reinforcing to hold it up. Under vulnerable conditions, reinforced concrete is a ticking time bomb. Unfortunately, the stock of reinforced concrete buildings and infrastructure requiring significant repairs is immense, and the expense to address all deficiencies may be well beyond manageable levels.

The implications are clear: Is the collapse of Champlain Towers South a harbinger of more to come? Will unfortunate news of the failures of other reinforced concrete structures become ever more commonplace as much of this building stock continues to age? Will all owners be able to afford what is necessary to secure the safety of their properties?

From my perspective as an architect, it’s time to rethink the widespread use of reinforced concrete. Despite its attractive properties, we now understand the material simply comes with many downsides, not the least of which is its environmental impact. When we do use reinforced concrete, we should do so sparingly and appropriately (protecting it from water’s deleterious effects). We should also exercise a standard of care consistent with the architectural profession’s evolving understanding of construction materials and their properties. That standard of care presumes a responsibility to employ all necessary measures in our designs to protect the public’s health, safety, and welfare. If this means limiting the use of reinforced concrete, so be it.

The collapse of Champlain Towers South should also be a wakeup call for developers, contractors, and facility managers. No design can withstand poor execution and years of neglect. Everyone with a role to play in the life of a building has a duty to ensure its safety and resilience.