The most inherent danger to people and property during the high winds of hurricanes is the flying debris carried in the high winds. Carried at such intense velocity, items such as 2 x 4's can become missiles that can cut right through a building wall and endanger the people inside. Tests conducted by Texas Tech Universitys Wind Engineering Research Center offer dramatic proof that concrete walls withstand flying debris from hurricanes and tornadoes and outperform their wood and steel counterparts.

To duplicate hurricane-like conditions in the laboratory, researchers shot wall sections with 15-pound 2 x 4 lumber "missiles" at up to 100 mph, simulating debris carried in a 250 mph wind. These conditions cover all but the most severe tornadoes. Hurricane wind speeds are less than the speeds modeled here, and missile tests designed to demonstrate damage from hurricanes use a 9-pound missile traveling about 34 mph.

Researchers tested 4 x 4-foot sections of concrete block, several types of insulating concrete forms, steel studs, and wood studs to rate performance in high winds. The sections were finished as they would be in a completed home: drywall, fiberglass batt insulation, plywood sheathing, and exterior finishes of vinyl siding, clay brick, or stucco.

All the concrete wall systems survived the tests with no structural damage. Lightweight steel and wood stud walls, however, offered little or no resistance to the "missile" and the 2 x 4 ripped through them.

Reinforced concrete homes have proven their wind-resistance in the field during tornadoes and hurricanes. In Urbana, Illinois, a recently constructed insulated concrete form home withstood a 1996 tornado with minimal damage. In the Liberty City area of Miami, several homes built using the shotcrete technique survived Hurricane Andrew in 1992. In both cases, neighboring homes were destroyed.

"The results of the tests were not surprising, but they were dramatic," says Donn Thompson, PCAs residential technologies program manager. "Concrete walls meet both the criteria needed to protect occupants in a severe storm: structural integrity and missile-shielding ability."

A trade association based in Skokie, Illinois, PCA conducts research, education, and public affairs work on behalf of its members, US and Canadian cement companies.

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