Natural Threat - Tornadoes

Counting only the month of May 2015 about 20 tornadoes developed in Germany. At least three of them reached tornado category F3 destroying villages, e.g. [15]. About 50 people were injured and the insurance companies recorded about 100 Mio. Euros insured loss. Press media headlined: Tornadoes in Germany - the underestimated threat? The forecasting of extreme weather conditions in Germany due to climate change is still very uncertain. The design codes in Germany do not consider tornado actions. Thus, they are still considered catastrophic events. But owners ask experts whether their home can actually be protected. In the USA tornado actions are defined in codes for critical infrastructure. Because of the frequency and intensity of tornadoes, people in the USA have experiences with such events. This article introduces the phenomena of extreme winds, defines actions generated by extreme winds, explains building vulnerabilities, and gives some guidelines on how to protect buildings. Because of lack of research in Germany concerning protection of structures against tornado actions, we benefit from the expertise in the USA. This article is aimed at sensitize for the tornado threat from an engineering point of view, showing related problems, and hopefully initiate research in the future.