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SPRING/SUMMER 1999 ARCHIVE Clemson Recognized as Leader in Orthopaedic Bioengineering Clemson University Mathematics: The Next National Champion? Clemson University, Southeast Leader in Invention Income Where the Rubber Meets the Roador Off-Road Clemson Students Win NSF Awards Professor Receives National Math Award Thomas Green Clemson Academy Welcomes Three New Members Dow Chemical Pledges More Than Half-Million Dollars to Film-Related Research Catfish: Improving Environment and Economy ACES Reunion and BBQ is Coming!  |
Blowin' in the Wind The Southeastern United States has historically been fertile ground for devastating hurricanes and tornadoes, and over the past decade, the severity and frequency of these killer storms have appeared to be on the rise. Clemson has one of the top research facilities in the nation designed specifically to study and mediate the effects of high winds on low-rise structures such as homes and schools. "We need to break the cycle of thinking that tornadoes and hurricanes are acts of God and that nothing can be done," says Ben Sill, Alumni Distinguished Professor of civil engineering at Clemson and one of the founders of Clemson's wind load test facility. The Clemson facility is unique in that it's the only one in the nation able to give a complete picture of the effects of wind on low-rise structures. Investigators measure both the strength of the wind load and the resistance of the building itself. Funded with a recent $73,000 grant from the Federal Emergency Management Agency, this research is being expanded to examine affordable ways in which interior rooms such as bathrooms and bedrooms can be reinforced to prevent damage by wind-blown debris and falling trees. The project studies ways rooms can be strengthened during initial construction or through the retrofit of existing homes. "This valuable research being done by Clemson will provide common-sense practical solutions to homeowners so they can have some piece of mind and, if they are in a tornado, they can be a degree safer," said John B. Copenhaver, director for FEMA's eight-state regional office based in Atlanta.
Early tests show that the dropped column smashes halfway through a typical 6-by-8-foot wall panel made of wood studs and fiberboard sheathing. The same column barely takes a bite out of a metal-reinforced panel. For a person asleep in a bed, that 3-foot differential could mean the difference between life and death. Roofs and other components will, of course, give additional levels of protection and will be factored into the final recommendations. "If the tree were to fall between the roof structural members and impact the plywood roof sheathing, the roof wouldn't make much of a difference anyway," warned Ed Sutt, a Ph.D student who is helping with the research. "And keep in mind, we're only seeing the effects of a 6-inch pine at this point. Larger trees could have far more devastating consequences." To simulate wind-borne debris, researchers use an air cannon to fire two-by-fours and other materials against wall sections at speeds up to and exceeding 100 mph. The Clemson research is concentrating on identifying inexpensive techniques that could be used by a construction-savvy homeowner. Research findings will be used to develop technical guidance for contractors and practical application suggestions for homeowners. Low-tech fixes under study include installation of wood-reinforced wall panels, the addition of a layer of metal decking under the wall panel, and different combinations of plywood or common insulation foams. "This won't lead to code changes, but we will come up with inexpensive suggestions that we think homeowners will want to include, particularly in new construction," said Sutt, whose research has led to a patented structural molding that will help keep homes intact in tornadoes, hurricanes and even earthquakes. "In many cases, better design and construction can save houses or lives," observed Sill. "Although some tornadoes or hurricanes will be so strong that extensive damage would be anticipated, it is not unrealistic to expect that most buildings should successfully withstand severe storms -- very frequently, though, that's not the case." |
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Testing structural components
against falling trees led researchers to develop what they call
the "The Drop Zone." The star of the zone is a 24-foot-tall
truck-mounted device that can lift and drop 1,500-pound columns
onto the structure being tested. Researchers are now evaluating
damage from 6-inch diameter pine trees by using a 20-foot-long
metal column weighing a quarter of a ton. Studies approximating
the effect of larger trees will eventually be tested.