F-Scale Exercise on Spencer Damage

Selected Scene 4 Slides and Comments by Respondents

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Slide 26 Slide 27

F2/F3: Empty one was light and acted as a sail.

none: Can't rate grain bins. Fujita scale does not apply.

F2: Grain bins damaged severely with those filled; however, nearly empty bin removed from bolted foundation.

F1: Grain bin damage usually occurs with winds.

F3: Grain bins toppled, yet trees still intact.

F2: Thicker metal, but tin.

F1: Older bins tend to be weaker at seams due to contraction over the years from the cycle of being filled and emptied, and heating and cooling.

F3: Because the tornado was really just rotating scud.

F2: Nearby trees still standing.

F2: Seen a lot of 80-100 mph wind do this to grain bins, center pivots, metal sheds, etc.

F3: Taken off bolts.

F4: Grain elevator gone, tied down, trees stripped.

F1: Would be F0 -- only the empty and near-empty bins gone -- but was anchored.

F3: Leaves gone, approximately 100 mph.

F3: Cylindrical elevator gone -- mass builds pressure. Trees snapped.

F3: A lot of trees standing.

F2: Grain?

F2: Smallish grain bin & anchoring in question.

F2: Large, empty grain bin does not need much to move.

F2/F3: Only a guess.

F2: Very high profile & low wind load rating.

F1: Full bin intact.

F2: Grain bins that had some grain in them were still standing.

F1: Corrugated metal implies a good sail.

F2: More bolts pulled through, but bigger structure & mostly empty.

F1: Large object, catches large volume of wind, typically not anchored sufficiently for size, wood sill plates typically rotted unless new.

F2: Elevator little damage.

F0: Have had grain bins moved off foundation with 55-65 mph winds!

F2: Hollow grain bin = "light missile"

F3: A guess.

F3: An empty grain bin is analogous to a typical house in the area.

F3: Why not?


Lubbock	        Scene 4 

Sample Size	62	 
Min F Scale:    1	 
Max F Scale:    4	  
# F Scales:     4	 
Mean F Scale    2.15625  
Standard Dev-
iation of F:	0.7948811

Norman	        Scene 4 

Sample Size	104	 
Min F Scale:    0	 
Max F Scale:    4	  
# F Scales:     5	 
Mean F Scale    2.043269  
Standard Dev-
iation of F:	0.7948811

St. Louis       Scene 4 

Sample Size	27	 
Min F Scale:    1	 
Max F Scale:    3	  
# F Scales:     3	 
Mean F Scale    1.925926  
Standard Dev-
iation of F:	0.67516


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