All buildings stand in potential disaster zones, be it tornadoes, hurricanes, or earthquakes, says Nadim Wehbe, the John M. Hanson Professorship of Structural and Construction Engineering and head of the Department of Civil and Environmental Engineering at South Dakota State University in Brookings.
“The future trend, if not the current trend, is to design structures for resiliency based on their risk categories,” Wehbe said.
After the recent storms in Illinois and Kentucky, including an F3 tornado that destroyed an Amazon warehouse and a factory in Kentucky, Wehbe highlights the need for resiliency in design.
“Resiliency is the ability of a structure to function following a major event. Resiliency is also related to acceptable damage level,” Wehbe said.
Wehbe cites bridge closure after an earthquake. We can accept bridge damage. We can even accept bridge closure. But we can’t accept bridge collapse and loss of life. Bridges play an essential role during cleanup and restoration in post-disaster communities, even if they can’t function at total capacity.
He references seismic upgrades that swept earthquake-prone areas in the 80s, 90s, and 2000s. Designers use the same standards when planning wind loads for buildings. Building codes list risk categories. A single-family home falls into category two, a hospital into category four. Category four buildings must survive significant events.
The Amazon warehouse where eight workers perished didn’t comply with category four standards. The walls, made from 40-foot by 11-inch concrete slabs, collapsed inward after the roof crumbled. “The walls themselves are strong enough to withstand any load, but looking at the collapse in these two facilities, it seems like the roof gave up first because of the suction pressure,” Wehbe said. “Once the roof is gone, the structure is gone, those walls are going to collapse.”
For now, Wehbe said, builders should make the necessary changes to structural integrity and resiliency, even if it is costly.