Engineers study tornado damage, offer suggestions | News

Engineers from the University of Alabama and other universities around the country have completed and released a study of the damage caused by the April 27 tornado, offering suggestions on what can be done to reduce the possibility of damage from future tornadoes.

The engineers spent weeks taking pictures and using a system called LIDAR to map the tornado damage. After compiling their data, they concluded light-frame wood buildings do not, and will not, have the ability to resist EF4 or EF5 tornadoes (the Tuscaloosa tornado was rated an EF4 by the National Weather Service.) The authors in their report reached the following conclusions:

1. The level of damage to light-frame wood buildings is not acceptable and can be reduced through new engineering design and construction practices.

2. The majority of residential buildings that suffer some level of damage in the path of a large tornado is caused by winds below the overall tornado EF rating assigned by the National Weather Service. Virtually all buildings in the path of a strong tornado, even along the outer edges where wind speeds are lower, are irreparable based on current design and construction practices. This provides incentive and an opportunity for tornado-resistant design and construction practices, which currently do not exist.

3. Damage to buildings on the outermost edges of the tornado appeared to be from inflow to the tornado vortex. This damage is mainly due to building penetration from debris strikes and wind speeds less than 130 mph.

4. Vertical load paths were not adequate, regardless of the age of the residential structure. Load paths appeared to be better provided on multi-family buildings.

5. Interior closets and bathrooms provide shelter at lower wind speeds on the edges of the tornado, but were no guarantee of survival. The concept of “safe spot” should still be taught, but a safe spot is not a substitute for a safe room or tornado shelter.

To see more of the case studies and pictures taken by the researchers, and to read their suggestions, visit:

http://esridev.caps.ua.edu/tuscaloosa_tornado/

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