Decades of research have gone into understanding tornadoes and how they impact buildings. Now that new understanding is making its way into building codes.
Credit: B. Hayes/NIST
Sirens blared across Joplin, Missouri, on a spring afternoon in 2011, just 23 minutes before the tip of the deadliest tornado on official records descended from the clouds and touched the ground.
This tornado maxed out the scale — a five out of five on the Enhanced Fujita (EF) scale, according to the National Weather Service.
Directly in the path of the vortex was St. John’s Regional Medical Center, a huge hospital complex that employed more than 1,000 people. The staff had done tornado drills before and quickly jumped into action, ushering patients and visitors away from the windows as dark clouds blotted out the sun. Then the lights went out. Ventilators stopped working. The storm had torn apart an electrical substation and the hospital’s emergency generator building, causing a total loss of power. The occupants were in complete darkness when the doors and windows blasted open, shooting broken glass and furniture through the hallways.
It took less than a minute for the mile-wide tornado to pass through St. John’s before moving on to tear through public schools, retirement homes, grocery stores, and suburban neighborhoods. The entire tornado lasted about 30 minutes, but by the end of it, a quarter of Joplin was destroyed and 161 people had lost their lives.
Just hours after the tornado hit Joplin, the National Institute of Standards and Technology (NIST) began a long-term study of what went wrong that day. After more than a decade of work, that research is making its way into standards and codes to make new buildings safer.
