Enhanced Fujita Scale Damage Indicators and Degrees of Damage

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

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)
DODDamage DescriptionEXP*LB*UB*
1Empty unanchored grain bin toppled; anchored grain bin damaged; silo cap damaged9070110
2Empty unanchored grain bin rolled or carried through air less than 10 m; anchored grain bin toppled; silo cap removed135110160
3Anchored grain bin rolled or carried less than 10 m; empty portions of stave concrete silos destroyed180150210
4Grain bin carried 10 - 100 m or more; stave concrete silo destroyed225190260

*All wind speeds in km/h