30' Tilt-up and K-Series OWJ Roof Collapse

[stellabella]

I am just starting to investigate the collapse of a distribution center with 30' high tilt-up panels that used K-series OWJ for the roof framing. The collapse oocurred during torrential rains (4"/hr), and the structure was only 4 years old. The roof pitched towards the parapet formed by the tilt-up panels. At the roof/parapet connection, there were roof drains and overflow scuppers. We do not have drawings yet.
QUESTION: Inasmuch as we are still at the information gathering stage, has anyone experienced similar failures? Any guidance out there? This occurred recently near Dallas.

 

[JedClampett]

No experience, but I think you already know what you're going to find. The scuppers/roof drains either didn't get put in, were inadequate or got clogged up. Maybe the roofing material partially covered the drains. Anyway, six inches of water would overload a normal 20 psf designed roof (without any reduction) by 50%.
Keep us posted.

 

[SlideRuleEra]

Unfortunately this happens all too often. Water starts ponding on the roof, the roof supports deflect, now more water can pond, more deflection... until failure.

Here is a listing of many examples:

http://www.senteck.com/need/incidence.html

 

[jheidt2543]

SlideRuleEra:

Thanks for the link, very interesting listing of roof collapses and the alarm system might be worth looking into for certain projects.

Another way of putting your commnet, the ponding problem is a "self reinforcing cycle", the more ponding the more defelction, the more deflection, the more ponding.