Shelters, research prevent tornadoes' effectsBy Judah Martin | 06/11/2013 11:00pm
Moore, Okla., is an unlucky town.
Situated in the Midwestern “Tornado Alley,” an informal term for the areas of North America where tornadoes are most common, the community has been hit by five devastating tornadoes in the past 15 years.
While there’s nothing residents can do to prevent these deadly tornadoes, that doesn’t mean they haven’t learned a few tricks for surviving them.
Andrew Graettinger, associate professor of civil, construction and environmental engineering, has worked with research teams to assess the disastrous effects of tornadoes in New Orleans, La., Tuscaloosa, Joplin, Mo., and Moore, Okla.
After receiving a multi-institution grant from the National Science Foundation Rapid Response Grant for Exploratory Research, Graettinger made the trip to Moore, Okla. He said he noticed tornado shelters saved the lives of many residents, a factor that contributed to a lower death toll there than any of the previous communities he had researched.
Graettinger said his research suggests there is more residents can do in the future to potentially save their homes.
“We would see evidence that the roof had been lifted off the houses,” Graettinger said. “Once you lift the roof off, there’s really not much support holding the wall up. It’s not really connected well to the foundation. In that 15 percent in the center of the storm, you still need a safe room or storm shelter. Even though the storm was EF5, probably 85 percent [of the impacted area] was [hit] at EF2 wind speed. Those areas we can start to engineer for, to protect.”
Working with Graettinger on the project is David O. Prevatt, assistant professor of civil and coastal engineering from the University of Florida, as well as engineers and researchers from The University of Alabama, Oregon State University, Mississippi State University, Oklahoma State University, Rose-Hulman Institute of Technology and Simpson Strong-Tie Co.
“What we do know, what we have found in other wind events like hurricanes, is that if we have a vertical load pass that ties the roof to the walls and we can tie all the building together, then it has a fighting chance to withstand these high winds,” Prevatt said. “As a first step, let’s see if we can get all buildings to have this vertical load pass.”
The Oklahoma study introduced an unlikely tool for researching natural disasters. At Mississippi State University, Arthur G. Cosby, the William L. Giles Distinguished Professor and director of the Social Science Research Center, employed the center’s Social Media Tracking and Analysis System in helping to map the affected areas in Moore.
“Our role was somewhat novel for this kind of research,” Cosby said. “SMTAS is a big suite of software. We can go in and filter down to the ones we want to look at. We select among these things what we’re looking for and start analyzing it to solve problems and to learn about a phenomenon. What happens in a storm is that people will go out with their iPhone and take a picture. They’re typically pictures of damage.”
While the building recommendations made by the team will certainly be helping in preventing future mass devastation, Prevatt said there’s not yet a definite way to ensure residents’ safety.
“[There are] other things that we really, really don’t know; there are phenomenon in the tornado which we do not understand,” Prevatt said. “There is a vertical suction and wind speed associated with vortex that protrudes very strong, well coordinated suction forced that can lift objects off the ground. That’s something that we don’t see in hurricanes or straight-line winds. We’re trying to research through experimental work and through working with the meteorologists to understand the magnitude of that suction force.”