Tis the Season: Structural Engineer Roueche discusses research of hurricane, wind events

The 2021 Atlantic hurricane season is well underway, with Hurricane Ida being the strongest storm so far. The latest storm system, Hurricane Nicholas, has weakened as it moved inland along the Texas gulf.

David Roueche is an assistant professor of structural engineering in Auburn University’s Samuel Ginn College of Engineering, where he researches ways of improving the performance of low-rise buildings under extreme wind loads, including hurricanes and tornadoes. Roueche has performed extensive field research in the aftermath of some of the strongest wind events in recent history, including the 2011 tornadoes in Tuscaloosa, Alabama, and Joplin, Missouri, the 2015 tornado in Garland, Texas, and several of the most recent major hurricanes. He uses the data captured from these events to develop better models of extreme wind loads and structural response, and ultimately strengthen the resilience of our communities to future events. Roueche serves as an associate member on the ASCE/SEI Standard for Estimating Wind Speeds in Tornadoes and Other Windstorms.

Last year, he received a $573,297 NSF Early Career award to investigate new methodologies that harness post-windstorm reconnaissance data in order to promote the resilience of buildings and communities and reduce future losses and other impacts.

Ida made landfall 16 years to the day of Hurricane Katrina. Have lessons learned from Katrina done enough to mitigate future disasters on that scale?

Clearly the answer is no, given the impact of Ida 16 years later. Unfortunately, what we see is that some lessons are learned, but not ever applied. Other lessons learned are applied, but only targeting specific failure points from past events without proactively addressing the more holistic needs for future resiliency, leaving us constantly chasing the latest failure. For example, after Katrina, New Orleans invested heavily in strengthening the levee systems. In Ida, the levees held, but all eight transmission lines providing power to the city failed due to wind effects, initiating a cascade of infrastructure failures that left most of the city without power and water. On a smaller scale, it’s been known for years that roofing products (shingles, metal roofing, etc.) are the first and most likely building elements to fail during windstorms, with the result being extensive, costly interior damage due to rainwater ingress and wind-driven rain. Low-cost solutions exist in the form of secondary water barriers, but are rarely implemented in typical construction. There is still much work to be done on both the engineering side and the policy and education side to see truly resilient communities in the future.

You have performed extensive field research in the aftermath of some of the strongest wind events in recent history. Why is this work important?

Nature is the ultimate living laboratory. We conduct our own laboratory experiments and run simulations and models and learn much from them, but tornadoes and landfalling hurricanes are still the ultimate test of how our structures and communities actually perform during extreme windstorms. The data we collect during field research feeds back into our labs and modeling efforts and becomes knowledge that is then transferred back to communities to make them more resilient. Expected economic losses from hurricanes alone are over $50 billion annually, so we still have much work to do for communities to be hardened and truly resilient to withstand future windstorms. Climate change and growing exposure in coastal regions magnifies the importance of these efforts even further.

There seem to be more and more hurricanes each season. Have coastal communities made enough advancements in structural integrity to recover faster, or is there more work to be done?

There has been progress, for sure. Stronger building codes, like those adopted in Florida, coastal counties of Alabama and a few other coastal states, can reduce losses by as much as 70%. Programs like Fortified® incentivize building stronger than the code minimum and have also proven to be very effective at reducing damage and losses. I personally see the benefits of these advancements in every hurricane, with strengthened buildings many times performing well right next to weaker structures that perform poorly. Despite the advancements though, there is still much more work to be done. Power and communications infrastructure is still highly vulnerable to extreme windstorms. Most communities also still live and work in a legacy building stock constructed well before the more modern building codes and standards were adopted, and it’s expensive to upgrade these to latest codes. Flooding and interior water damage is also still a costly threat during windstorms, even if our buildings structurally perform well.

What are low-rise buildings, and how has your research effected the structural integrity of them?

Low-rise buildings are buildings with average roof heights less than 60 feet. The majority of buildings fit in this class. My research is improving their structural integrity by improving our understanding of design wind loads and how they act on structures and unpacking the key factors that are either correlated or directly causal to improved performance and occupant survivability. Specifically with my NSF CAREER proposal, I am merging past datasets containing hundreds and thousands of individual post-windstorm building assessments from past storms into one unified database, then blending theory and data science in hybrid models that can assess causality in a powerful way. Outcomes will not only improve structural integrity, but will also provide unique opportunities to educate the public on the most important ways we can build better and get better performance during extreme windstorms. 

How will Auburn’s new Advanced Structural Engineering Lab help your research?

Having a state-of-the-art facility like the Advanced Structural Engineering Lab complements my field research perfectly. As an example, I’m currently assembling extreme wind load testing equipment in ASEL, called Pressure Loading Actuators, that can replicate the exact wind pressure traces buildings experience during the worst of windstorms (Category 5 hurricanes and EF 5 tornadoes) on component and cladding elements of buildings (e.g., windows, doors, roofing, subframing). This will allow me to confirm anecdotal information I find in the field, and test new and better ways of building and connecting components going forward. In general, though, whether it be testing better power pole or manufactured home anchoring (utilizing the one-of-a-kind geotechnical chamber in ASEL), hybrid steel-mass timber beams, better garage doors or almost anything else, this lab has the capability of testing it to failure. This is a game-changer for us being able to contribute to innovative, better-performing buildings and other infrastructure and I’m excited to be a part of it all.