Enhanced Fujita scale damage indicators and degrees of damage, chapter 30


C-5 Farm Silos or Grain Bins (C-FSGB)

Typical Construction:

Farm silos

  • Cylindrical structures typically 4-10 m in diameter and 20-50 m in height
  • Construction is wood staves, concrete staves, cast concrete, poured concrete or steel panels
  • With cast/poured concrete and Harvestore steel silos, increase toward upper-bound wind speed

Grain bins

  • Cylindrical structures typically 5-20 m in diameter and 5-30 m in height
  • Construction is galvanized steel panels and purlins
Table 30. Degree of Damage (DOD) for Expected (EXP), Lower Bound (LB) and Upper Bound (UB)
DOD Damage Description EXP* LB* UB*
1 Empty unanchored grain bin toppled; anchored grain bin damaged; silo cap damaged 90 70 110
2 Empty unanchored grain bin rolled or carried through air less than 10 m; anchored grain bin toppled; silo cap removed 135 110 160
3 Anchored grain bin rolled or carried less than 10 m; empty portions of silo destroyed 180 150 210
4 Grain bin carried 10-100 m or more; silo destroyed 225 190 260

*All wind speeds in km/h

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