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Severe WX April 29-May 2nd, 2022 Severe Weather Threat

The pet store (which I hope was either closed or did not house actual pets at the time of impact at least?) appears to be right across the road from the YMCA so if this is violent damage it was definitely caught on high definition video from multiple angles
 
OHWX97 said:
Reed Timmer's drone footage from yesterday.
Click to expand...

Never seen anything quite like this. Just the other day I was thinking about how with the addition of drones in chasing, eventually we are going to have HD aerial video of homes being destroyed in a populated area in detail like we’ve never seen before. Didn’t think it would come to fruition just days later.
 
buckeye05 said:
Yup that’s definitely what that is. Also, Google maps street view shows that the pet shop was housed in an unusual arch-shaped/Quonset hut-like structure.
Click to expand...
Interesting, would it still be considered well-built or did the unusual building structure potentially lead to the building’s failure during the tornado?
 
SouthFLwx said:
Interesting, would it still be considered well-built or did the unusual building structure potentially lead to the building’s failure during the tornado?
Click to expand...
I'm a contractor, not an engineer, but I've spent much of my 40+ years in the business analyzing loads, designs, plus failure modes and patterns as a special interest. I haven't studied the pics in great depth but I have noted much in the short time I've looked.

This design is unusual and will therefore not be used for damage assessment regards normal DI's. What will likely occur is the truss engineer who designed this will be consulted to determine the wind-speed rating it was designed to later on. I've seen and studies a couple of similar buildings and here's my take on this:

The ends are much like gable ends on a normal roof, but of larger area and thus being weaker unless well-braced. Such bracing would not have anything of strength to transfer the load to without there being a 'loft' floor, which seems absent. The only other possible bracing would be using purlins between the trusses at the level of a gable beam (8" to 10" level) to brace the ends of the beam, which would not add much strength.

The trusses rely on the sheathing or skin for lateral rigidity. It that was the usual 1/2 OSB nailed correctly we can presume good lateral strength, but if it's only metal skinning it would be somewhat weak. Side-loading would be up to truss design, and I can't see enough to assess that well, but it appears that these trusses were not strong as I can see little distance between the chords in what remains, and that distance plus "V" bracibng is what determines the amount of strength available. Also the two similar buildings I've seen like this were similar.

Failure was likely through displacement or breakage of an end creating over-pressure inside similar to a garage door failing. That probably caused detachment of the sheathing or skinning causing a rapid loss of lateral strength resulting in the whole thing being blown down in a 'domino' collapse. It could have caused wall or plate lift failure but that doesn't seem to be the case here. It it simultaneously blew the far end out the Coanda effect would have caused over-pressure to change to under-pressure overloading the trusses into collapse.

tldr: This is a weak design for wind resistance and would not likely equal a normally built home, and almost certainly not a well-built one. Done correctly this could be a strong design but I see no evidence of that.

Phil
 
Sawmaster said:
I'm a contractor, not an engineer, but I've spent much of my 40+ years in the business analyzing loads, designs, plus failure modes and patterns as a special interest. I haven't studied the pics in great depth but I have noted much in the short time I've looked.

This design is unusual and will therefore not be used for damage assessment regards normal DI's. What will likely occur is the truss engineer who designed this will be consulted to determine the wind-speed rating it was designed to later on. I've seen and studies a couple of similar buildings and here's my take on this:

The ends are much like gable ends on a normal roof, but of larger area and thus being weaker unless well-braced. Such bracing would not have anything of strength to transfer the load to without there being a 'loft' floor, which seems absent. The only other possible bracing would be using purlins between the trusses at the level of a gable beam (8" to 10" level) to brace the ends of the beam, which would not add much strength.

The trusses rely on the sheathing or skin for lateral rigidity. It that was the usual 1/2 OSB nailed correctly we can presume good lateral strength, but if it's only metal skinning it would be somewhat weak. Side-loading would be up to truss design, and I can't see enough to assess that well, but it appears that these trusses were not strong as I can see little distance between the chords in what remains, and that distance plus "V" bracibng is what determines the amount of strength available. Also the two similar buildings I've seen like this were similar.

Failure was likely through displacement or breakage of an end creating over-pressure inside similar to a garage door failing. That probably caused detachment of the sheathing or skinning causing a rapid loss of lateral strength resulting in the whole thing being blown down in a 'domino' collapse. It could have caused wall or plate lift failure but that doesn't seem to be the case here. It it simultaneously blew the far end out the Coanda effect would have caused over-pressure to change to under-pressure overloading the trusses into collapse.

tldr: This is a weak design for wind resistance and would not likely equal a normally built home, and almost certainly not a well-built one. Done correctly this could be a strong design but I see no evidence of that.

Phil
Click to expand...
Very nice post Phil.
Good to see someone that is realistic on here instead of calling every tornado an EF-5
 
Sawmaster said:
I'm a contractor, not an engineer, but I've spent much of my 40+ years in the business analyzing loads, designs, plus failure modes and patterns as a special interest. I haven't studied the pics in great depth but I have noted much in the short time I've looked.

This design is unusual and will therefore not be used for damage assessment regards normal DI's. What will likely occur is the truss engineer who designed this will be consulted to determine the wind-speed rating it was designed to later on. I've seen and studies a couple of similar buildings and here's my take on this:

The ends are much like gable ends on a normal roof, but of larger area and thus being weaker unless well-braced. Such bracing would not have anything of strength to transfer the load to without there being a 'loft' floor, which seems absent. The only other possible bracing would be using purlins between the trusses at the level of a gable beam (8" to 10" level) to brace the ends of the beam, which would not add much strength.

The trusses rely on the sheathing or skin for lateral rigidity. It that was the usual 1/2 OSB nailed correctly we can presume good lateral strength, but if it's only metal skinning it would be somewhat weak. Side-loading would be up to truss design, and I can't see enough to assess that well, but it appears that these trusses were not strong as I can see little distance between the chords in what remains, and that distance plus "V" bracibng is what determines the amount of strength available. Also the two similar buildings I've seen like this were similar.

Failure was likely through displacement or breakage of an end creating over-pressure inside similar to a garage door failing. That probably caused detachment of the sheathing or skinning causing a rapid loss of lateral strength resulting in the whole thing being blown down in a 'domino' collapse. It could have caused wall or plate lift failure but that doesn't seem to be the case here. It it simultaneously blew the far end out the Coanda effect would have caused over-pressure to change to under-pressure overloading the trusses into collapse.

tldr: This is a weak design for wind resistance and would not likely equal a normally built home, and almost certainly not a well-built one. Done correctly this could be a strong design but I see no evidence of that.

Phil
Click to expand...
Awesome breakdown. Would love to hear more of your input here.
 
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