The catastrophic collapse of the Champlain Towers South Condominium in Surfside, Florida, has shaken the engineering community and the public alike. Our team at Troca Global has investigated the causes behind this tragedy to help give guidance to building managers and prevent such incidents from reoccurring in the modern era.
The Investigation and Findings
On July 4, 2021, TGA published a preliminary paper outlining several potential causes of the collapse:
Extensive corrosion of reinforcing bars
Liquefaction of foundation soil
Improper design with smaller concrete sections or insufficient reinforcement
Proper design but flawed construction not adhering to the drawings
Neglect in repairing damages
Recent studies have confirmed that most of the above causes, with the exception of liquefaction and improper design with smaller concrete sections, were significant factors in the catastrophe. The primary issue traced back to the ground-floor pool situated atop the concrete slab of the underground parking garage. An inspection report from 2018 highlighted that improper waterproofing below the pool had led to severe structural damage, allowing water to leak and corrode the reinforcing bars in the beams, columns, and walls.
The Corrosion Effect
Understanding the corrosion effect on reinforcing bars within structural concrete members is crucial. Concrete and steel bars together provide the strength needed to carry imposed loads. However, when hairline cracks in the concrete are exposed to salty, water-saturated air, the steel bars inside begin to rust. Rust expands more than the original steel, widening cracks and allowing further water and air penetration, accelerating the rusting process. Eventually, the steel bars can disintegrate entirely, causing the concrete members to fail.
Preventive Measures and Recommendations
To halt the rusting process and prevent structural failure, timely repairs are essential. Regular engineering inspections should be conducted, especially in areas with salty or polluted air. Any signs of wider cracks or rusting must be addressed promptly with appropriate maintenance processes.
It is also imperative that buildings, particularly those situated near the ocean, follow stringent construction practices. This includes ensuring that the construction adheres to design drawings and that independent engineering inspections are performed before pouring concrete for columns, beams, and slabs.
Addressing Foundation Failures
While foundation failures were not primary causes in this instance, they are worth discussing. Foundations built on sandy soils can lose their strength when saturated with water and subjected to vibrations. Proper soil investigations should be conducted before constructing foundations to ensure they can support the imposed loads.
Conclusion
The Surfside collapse underscores the necessity for rigorous quality control, regular maintenance, and adherence to design specifications in construction. Building owners, managers, and engineers must prioritize structural integrity to prevent future tragedies. By learning from the Surfside disaster, we can ensure safer, more resilient structures for our communities.
BOSTON ● OCTOBER 24, 2021
About the Author
Dr. Mukti L. Das, Senior Technical Advisor
Dr. Mukti L. Das is Senior Technical Advisor to Troca Global Advisors. As a Fellow of the American Society of Civil Engineers, an honor bestowed upon less than three percent of American civil engineers, Mukti has more than 40 years of engineering experience on nuclear, fossil and hydroelectric power plants, pulp and paper manufacturing facilities, underground structures, road and railroad bridges, high-rise structures and other industrial facilities. Mukti currently serves as the Chairman of the American Concrete Institute Subcommittee on Foundations for Dynamic Equipment.
A leading global structural expert, Mukti serves Troca Global Advisors and its clients for all engineering related issues, including structural forensic engagements, investigating and determining the causes of structural failures of buildings, bridges and other facilities. Mukti renders opinions and provides testimony in court and other judicial proceedings.
Formerly a Principal Civil Engineer at Bechtel Power Corporation and a member of the accreditation board for ABET, Mukti holds a Ph.D. and M.S. from the University of Massachusetts, Amherst and a B.S. from the University of Calcutta. He’s also our German expert (he lived in Germany for years, is fluent in German, and savors his beloved Franziskaner-Bräu).
About Troca Global
Troca Global Advisors and its affiliated companies provides high value advisory services to clients across disciplines and around the world who seek solutions to critical, interesting and often complex issues. The firm is dedicated to achieving pragmatic and efficient results for our clients based on years of multi-disciplinary experience. The exceptionally broad expertise of our network allows us to advise our clients in a large array of disciplines.
Our Structural Services Team, led by Dr. Das, provides guidance to owners and managers of buildings, bridges, roadways, and facilities regarding a wide array of structural stability, health and safety issues.