TERRE HAUTE —
Few forces of nature cause more damage than a tornado, and getting to the bottom of those storms is one Rose-Hulman professor’s goal.
In July, Fred Haan returns to Iowa State University for a summer of collaborative research about the structural impact of winds and what can be done to make buildings more resistant.
The Rose-Hulman Institute of Technology professor of mechanical engineering has served as collaborative faculty with Iowa State projects for the last 10 years, and he said this interest stems back to a childhood mixture of fascination and fear.
Haan’s work was recently featured in a USA Today article about research aimed at making buildings stronger. Among other projects, he works with a tornado simulator and 5-inch-tall model houses to test for loads.
“It doesn’t take building a concrete house to make it more wind resistant,” he said last week inside his office at Rose-Hulman.
After witnessing the disastrous impact of storms such as those which leveled Joplin, Mo., many people assume tornadoes are simply too powerful to withstand, he said. But 90 percent of tornadoes are EF2 or less, with wind speeds ranging between 110 and 135 miles per hour. That’s roughly the equivalent of a hurricane, Haan remarked, and people don’t simply give up building along the coasts.
The “monster” storm which hit Joplin was an EF5, which is a category of tornadoes where wind speeds exceed 200 miles per hour, he said.
Those are indeed tough to build in preparation for, but the research he’s working on could be used to construct hospitals and power plants which need to be protected, he said.
On his desk was a small box full of pressure sensors he explained fit into the small model houses they develop. In addition to computer modeling, the group uses a tornado simulator to blast over the houses and record the data. Another project in which the group is working involves the speeds and impact of debris which flies about during the storms, he said.
In some cases, better construction practices can make a big difference, he said. The manner in which a roof is connected to a house’s trusses, and the trusses to the walls, can determine whether the structure flies apart or not under various winds, he said.
In a tornado, the speed of the side winds isn’t nearly as problematic as the vortex, he said.
A house can withstand a great deal of wind from the sides, but the forces of the vortex, which suck the roof right up and off the house, are “significantly higher in the tornado” than a hurricane, he said.
Those forces sucking up from the bottom can be as much as two to three times more powerful than the straight winds, he said.
Haan said he’s proud of the volume of engineering numbers his group has produced as they continue to test loads and make recommendations on building practices.
Still, the biggest mystery about tornadoes is what’s going on at the bottom.
Predicting when and where tornadoes will strike is tough enough and getting radar equipment up close is equally problematic, he said. But even when one does get equipment close, trees and other structures often block out the bottom 30 feet or so. Some models suggest that the wind speeds of a tornado should be slower at the bottom than the top, but Haan said other models lean the other way, indicating that wind speeds near the ground are incredibly fast and destructive.
The best way to find out is more research, and Haan said he’ll be taking an undergraduate along with him to Iowa State next month.
In the meantime, tornado season officially ended in May, but Haan pointed out that every state in America and every month of the year have been hit by at least one over the years.
Brian Boyce can be reached at 812-231-4253 or email@example.com.