Roof Collapse/Fire in Phoenix

[JedClampett]

See Safeway Roof Collapse.
No one has determined yet the order of problems, but early reporting said the roof collapsed first, possibly due to ponding, which caused the fire. Note that this is in Phoenix, where there's very little foliage to clog roof drains. Of course, it only rains every year or so, so if they're clogged, you might never know.

 

[RickyTickyTavi]

Doesnt IBC call for a a secondary drainage system for flat roofs? For example: scuppers

 

[JohnRBaker]

Have you ever been in Phoenix when they had one of those enormous dust storms that collides with a thunderstorm? I have, and it linearly rained mud. Just last week there were reports that this is exactly what happened. The real problem is that these summer thunderstorms only last about 10 mins or so, enough to clear the skis of much of the dust but not enough to fully wash the resulting mud away. This could have very easily clogged the roof drains, then harden so that the next time it rained, there was no place for the run-off to go.

https://www.azcentral.com/story/new...st-storm-traveled-nearly-200-miles/781444002/

https://www.express.co.uk/news/worl...-monsoon-storm-pictures-latest-video-USA-news

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Irvine, CA
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[IRstuff]

The article seems really confusing; it talks about the roof collapsing causing the fire, yet, it describes the firefighters in the building evacuating as the roof starts to collapse. How were they able to clear the occupants if the roof had already collapsed?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[Spartan5]

IRstuff: Partial collapse -> fire -> total collapse

 

[IRstuff]

I understand that concept, but "As they were doing that, a section of roof collapsed," suggests that this was the first, and possibly only collapse, otherwise, it would read, "As they were doing that, another section of roof collapsed."

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[hawkaz]

I'm calling this one an engineering success! No people killed or injured and the fire wall between this structure and the adjacent shops appears to have worked. It's amazing that a fire of this intensity did not spread to the adjacent part of the building.

 

[MrHershey]

Doesnt IBC call for a a secondary drainage system for flat roofs? For example: scuppers

Both IBC and ASCE 7 kind of imply it's required. Don't know if there's a clear requirement for a defined secondary drainage system anywhere in the non-structural portions of the code or if just letting water run over the edge of the roof curb (for example) qualifies as a 'secondary drainage system'.

I do know that both IBC and ASCE 7 require that water depth for determining rain loads account for the possibility that the primary drainage system is blocked or otherwise inoperable.

 

[hawkaz]

FYI,
From a google maps view- this building did have scuppers. Unfortunately, very few owners in Phoenix clean their roof drains, and the scuppers can get overwhelmed during a monsoon rain (like the one that happened at the time of this collapse).

It was stated that a gas leak may have caused the fire- from that google maps view, it looks like the gas meter was directly below one of the scuppers.