Building Stronger

Most of the damage and debris in Joplin has long since been cleaned up, but a few houses still stand in their wrecked condition, a jumble of ruined structures and abandoned possessions. Here, a piano sits amid splintered framing in an older neighborhood near the high school.

An underfloor crawl space is described as a “safe area” in tornado preparedness literature. However, the risk is still substantial for homeowners who seek refuge in any hiding place in a typical older house. Here, the block foundation has been shattered and the floor has fallen down; upstairs rooms were mostly completely destroyed. An engineered safe room or tornado shelter is far more reliable as a refuge than any part of a conventionally built wood house.

The majority of the first story framed walls and the roof of this commercial structure, a dentist office built only two years earlier, remained standing after the tornado. Many nearby older buildings collapsed, with significant loss of life. This structure was built to a more modern code edition and included structural elements required by the commercial building code, including steel connectors at every roof truss to wall connection.

A rusted strap shows where the connection between a window unit and the rough opening failed during the storm. All the windows in this structure, a dentist office, were blown in during the tornado, making the interior space unsafe and likely unsurvivable. The office was closed on the Sunday evening when the storm struck.

Collapsed gable trusses on a bump-out section of the dentist’s office on South Jackson Street in Joplin. An improved truss bracing system in this building element might have allowed this assembly to withstand the storm.

Toenails, as well as the nails in the steel connector tying this truss to the bearing wall, failed in withdrawal during the storm. Ring-shank nails or threaded fasteners might have been sufficient to prevent the failure of this connection. However, engineers generally agree that it is impractical to design wood-frame structures to resist the wind force in an F-3, F-4, or F-5 tornado.

A concrete in-ground shelter outside a new building in Joplin. Buried tornado shelters offer the advantage of protection by the earth. However, they have the disadvantage that the resident needs to leave the home and risk the severe conditions outdoors in order to enter the shelter.

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