Are Target Performance Objectives Consistent with Recent Damage Observations?

Severe tornados struck the central and southern United States late on December 10, 2021. The heavy damage and the associated loss of life, which received extensive coverage by U.S. media outlets and piqued the general public’s interest, raised questions regarding the relative risks to structures from various natural hazards, including wind, tornadoes, earthquakes, floods, and fires. The damage from these tornados appeared to the casual observer disproportionate to the structural damage from other hazards such as hurricanes and earthquakes. Moreover, the tornado outbreak coincided with the release of ASCE 7-22, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, which includes a new Chapter 32 related to tornado loads and raised the profile of performance under tornado loads in the minds of practicing structural engineers. This article focuses on how risks associated with different hazards are considered by structural engineers in current design standards and whether the devastation observed in December 2021 is somehow inconsistent with these approaches.