Better Building Codes Urged for Tornado, Hurricane Regions

(NOAA.gov)

Researchers and engineers from universities and industry that reviewed the damage caused by destructive Spring 2011 tornadoes in the U.S. call for more intensive engineering design and more rigorous, localized construction and inspection standards to reduce property damage and loss of life. The report of the group’s research on the Tuscaloosa, Alabama tornado on 27 April 2011, funded by the National Science Foundation, is available online from the Center for Advanced Public Safety at University of Alabama.

The team found widespread damage to light-frame wood homes from the tornadoes, even at the outer edges of the storms where wind speeds are lower. At the outer edges, much of the damaged was caused by flying debris, even where winds were less the most severe storm ratings (under 130 mph).

They called the level of damage “unacceptable,” which could be reduced through new engineering design and construction practices. Yet, better design and construction could probably not provide adequate protection against the most severe (ratings of EF4 and EF5) tornadoes, with winds of 166 mph and higher.

Also, tornadoes and hurricanes will affect buildings in different ways. These storms apply different types of forces to buildings, and what may protect a building from one type of storm event may not work with the other. Implementing hurricane-region construction practices and codes in a tornado-prone region is a good start, but not an end solution.

The construction industry, says the report, needs a better understanding of the way tornadoes affect buildings. Testing in wind-tunnels using straight, strong winds does not simulate the turbulence, flying debris, lateral wind pressure, and suction found with tornadoes. The industry needs more realistic simulations and tests.

In areas prone to severe storms, shelters or safe rooms designed to withstand the wind pressure and flying debris are recommended, in both new and existing buildings.

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