I’ve been in several buildings designed to withstand tornados. Anything above around typically is only designed to survive and F3 or F4. The ones I’ve seen have

I’ve been in several buildings designed to withstand tornados. Anything above around typically is only designed to survive and F3 or F4. The ones I’ve seen have a strong outer shell of steel and concrete with some angles to help deflect wind. There’s then an inner shell of steel designed to keep what ever is inside safe. The outer shell will let some debris through but it won’t penetrate the inner concrete and steel shell. To put it in perspective an F5 (strongest tornado) will leave just dirt behind and all structures, vegetation, and soil will be gone. Here’s an example of an F5 aftermath in Illinois in the 90s https://www.weather.gov/images/lot/pastevents/1990/Aug28/plainfield6.jpg https://www.weather.gov/images/lot/pastevents/1990/Aug28/pla...