When Hurricane Dorian and its 185 mph winds mauled the Bahamas in 2019, it was a wake-up call for disaster researchers.
The massive cyclone narrowly avoided Florida but compelled scientists there to consider the scenario of a Dorian-like storm hitting home, especially in a world in which such storms are becoming more intense because of climate change.
At Florida International University (FIU), scientists imagined a new facility to test how buildings would hold up against tempests like Dorian.
“Dorian, for us, was a near miss from which we should be learning” said Richard Olson, head of FIU’s Extreme Events Institute.
In January, FIU was the recipient a four-year, $12.8 million grant from the National Science Foundation to design a facility that will subject makeshift homes and other structures to winds of 200 mph and a storm surge of 20 feet. The surge is the storm-driven rise in ocean water above normally dry land at the coast.
The endeavor will involve scientists from nine universities across the country and provide new insights into how to fortify cities against increasingly ferocious storms.
“What we are trying to do is simulate what we have seen in the last 10 years, where wind speeds are reaching almost 180 to 200 miles per hour,” said Arindam Gan Chowdhury, a professor of engineering at FIU and principal investigator on the project.
As oceans warm, the world is seeing more powerful hurricanes that spin up faster and deliver heavier downpours, with rising seas producing greater storm surges.
Chowdhury envisions the new project will comprise an array of 24 fans about 60 feet wide and 40 feet tall, though such figures are preliminary, he stressed, as scientists work to develop the National Full-Scale Testing Infrastructure for Community Hardening in Extreme Wind, Surge, and Wave Events — or NICHE, for short.
The array of fans will sit at one end of a 200-foot-long wave basin, with a test structure resting on a turntable at the opposite end. Fans will produce high-powered winds, like those seen in a hurricane, thunderstorm or tornado, while paddles or pistons will generate waves. Pressure sensors, accelerometers, strain gauges and other instruments will measure the impact of wind and water on the test structure. “We want to see how much it can withstand before it breaks up,” Chowdhury said.
NICHE will build on research conducted using FIU’s Wall of Wind, a set of fans that can pelt solar panels, traffic lights, small buildings and other test objects with winds up to 157 mph — the minimum speed of a Category 5 cyclone. The Wall of Wind was built to simulate the power of 1992’s Hurricane Andrew, which inflicted $27 billion in damages in South Florida and killed 65 people. The Wall of Wind can’t, however, replicate the winds or floods associated with a new generation of Dorian-like storms.
“We have facilities that can look at the impact of wind loads on structures. We have facilities that can look at the impact of storm surge and waves on structures,” said Joy Pauschke, NSF program director in the division of civil, mechanical and manufacturing innovation. “But we don’t have a facility that can look at the coupled interaction of having both the wind loads and the wave loads on structures.”
Existing testing sites can test these elements only in isolation and accommodate only relatively small test objects. FIU’s Wall of Wind is about 20 feet wide and 14 feet high, large enough to overwhelm a low-rise building with powerful gales, but too small to test a multistory home. The Large Wave Flume at Oregon State University can test storm surges by sending powerful waves down a narrow channel to crash into barriers on the other end, but like the Wall of Wind, it is limited in scale.
NICHE will test the interaction of wind and waves on structures as large as a two-story house. Incorporating storm surge is a key advantage of the project, since it is water, not wind, that produces the most damage during a hurricane, so much so that some experts have argued that the current wind-based rating system should be replaced with a new scale that factors in flood risk.
With hurricanes striking only sporadically during the warm months, scientists have limited opportunity to study their impact in the real world. NICHE will allow researchers to investigate hurricane damage year-round in a controlled setting. Their findings will complement the work of post-disaster reconnaissance teams, which survey damage from hurricanes, earthquakes, tornadoes and other events to see how well buildings held up. Data from NICHE will also help scientists identify weaknesses in computer models of hurricane damage.
“It’s pretty much the best shot that you can have from an engineering standpoint to be able to simulate all the complexities of a hurricane,” said Gonzalo Pita, a research scientist at Johns Hopkins University specializing in disaster risk who is not affiliated with the project. He said that such research is usually cost-effective, as the findings prevent greater damage in future disasters.
“Eventually the research finds its way, for example, into building codes,” Pauschke said. An NSF-funded shake table at the University of California at San Diego, for instance, has been rattling structures up to five stories tall to test their fitness for earthquakes, with the results informing new construction technologies and design codes.
Olson said NICHE will involve disaster specialists including experts from the University of Florida, Oregon State, Stanford, Notre Dame, Georgia Tech, Illinois, Colorado State and Wayne State, as well as Aerolab, a manufacturer of wind tunnels.
Scientists will first produce a prototype that will consist, perhaps, of just two fans overlooking a small reservoir. They will then use the data collected from this prototype, as well as from computer models and real-life storms, to create their final design. “You need this team, because this expertise just doesn’t come from one university,” Chowdhury said.
Once they have settled on a design, they will build the facility, which could be unveiled by 2030, contingent upon additional funding. Given how long it will take to plan and build such a sophisticated test site, and how quickly temperatures are rising, scientists are eager to get to work, Olson said.
“I wouldn’t want to be trying to explain to the public in 20 years why we didn’t do this,” he said. “If we’re being affected by stronger storms, I don’t want to be trying to explain why we didn’t do this research and testing ahead of time.”
