Tornado outbreak sequence of May 21–26, 2011
On May 22, a large, devastating EF5 tornado tracked through Joplin, Missouri, leaving behind catastrophic damage. It was a multiple-vortex tornado in excess of wide. Mainly the southern part of the city was affected with most structures in the area either damaged or destroyed. 162 people were killed along the path through Jasper and Newton counties in Missouri, making it the deadliest U.S. tornado since 1947, and one of the deadliest single tornadoes ever recorded. Among the most heavily damaged structures was St. John's Hospital (pictured right), which later was torn down due to the severity of the structural damage. Damages were estimated at around $2.8 billion (2011 USD).
The Home Depot
In the wake of the 2011 Joplin tornado in which the walls of a Home Depot collapsed after being hit by an EF5 tornado, "The Kansas City Star", citing engineers, criticized Home Depot's practice of using tilt-up construction in hundreds of its big-box stores (other nearby big-box stores in Joplin, including a Walmart and Academy Sports, which had concrete block construction, lost their roofs but the walls remained intact). In tilt-up construction the concrete is poured onsite, lifted into place, and then attached to the roof. The engineers told the "Star" that the practice, while normally safe and efficient, is dangerous in major storms because once the roof is lifted (as happened in Joplin) the walls collapse in a domino effect. Seven people were killed in the front of the store when the 100,000-pound walls collapsed on them, while 28 people in the back of the store survived when those walls collapsed outward. Only two of the slab walls in the Home Depot survived. In contrast, 3 people died in the Walmart but 200 survived. Engineers noted that when concrete block construction fails, structural elements break in pieces and usually not in huge slabs. Home Depot said it fundamentally disagreed with the engineers quoted by the "Star" and said it would use tilt-up construction when it rebuilds the Joplin store.