Roof Collapse Due to Snow 1

[StrucDesignPE]

Roof on a school in Michigan collapsed last week due to snow load. Engineer investigating says it was due to defects in the roof trusses. Has some interesting pics and video.

First article talks about event:

http://www.keweenawreport.com/news/...t-barkell-elementary-following-roof-collapse/

This article has video:

https://www.wilx.com/content/news/School-roof-partially-collapses-under-heavy-snow-507199841.html

This article says that engineer investigated and determined collapse was due to defective trusses:

http://www.mininggazette.com/news/2019/03/defective-trusses-caused-collapse-of-schools-roof/

 

[JohnRBaker]

I went to school just across the lake from Hancock and my brother lives about 30 miles from there. He sent pictures last week showing that he was 'snowed-in' after getting 24 inches of snow in 24 hours.

One thing that I haven't heard or read anywhere, is how old the building was. It looks fairly new but there's no mention whatsoever when the building was constructed. I have some contacts at the university and I'll inquire and if I hear anything I'll post it.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[JohnRBaker]

I heard from a couple of my contacts at the university and one of them (who was my statics and dynamics instructor back in the day) provided me with info that showed that this school building was opened in 1989, so it appears to be a 30 year old roof system.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[StrucDesignPE]

Given the average snow fall there, it seems pretty crazy that this lasted as long as it did with these apparent defects in the roof trusses. I wish more explanation was available as to what the exact defects were. Based on the video in the link above and the pic attached, looks like an area for snow drift.

 

[Fuzzbean]

Hey, that is the top of my step-daughter's head on the right there!

I was at the school board meeting the Daily Mining Gazette article about defective trusses was based on. Strangely the article does not make clear one thing the OHM engineer told us -- that the school board and school administration were aware beforehand that the trusses were defective. In fact OHM already had plans drawn up to correct the defects, but were waiting until the end of the school year to start the work. Yet the school administration was making no special effort to keep snow off the roof this winter, especially the rear roof. Look at the photos in the Keweenaw Report article in the first link. Note the difference between the snow piles on the ground at the front of the building (heaped as high as the roof eaves) and the snow pile at the rear of the building (more of a drift than a "pile" and half the windows showing). If you do a Google image search for "Barkell snow roof" you can see larger versions of the same photos.

If I sound a bit mad, it is because my 6 year old daughter goes to that school and was under that roof every day. It was an actual classroom that caved in, one that would have been full of kids 8 hours later, and there are/were more defective trusses in other parts of the building too.

 

[JohnRBaker]

One of my classmates from school, a local, works for the company that provided much of the building materials used to construct the school back in 1989, but he says that after 30 years he's not sure if they still have any records showing exactly what they sold the contractor or where the materials were sourced from.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[StrucDesignPE]

What were the defects in the trusses? Usually, when I look at truss issues, it is because of cracked web members or chords, especially near knots in the wood. Occasionally, it will be due to a metal plate missing or not fully seated.

 

[Fuzzbean]

The OHM engineer is now flatly refusing to speak to the press, but my impression is that the same defect was duplicated in 12 of the trusses, and that it was a consistent deviation in construction from the intended design. That may not be correct, though. I think there is a separate issue of "lateral bracing" not being there, as well.

Yes I feel like I'm gossiping/speculating in a non-technical way and I apologize for that, but school district officials have been totally focused on what a great adventure the kids are having, and have not made any effort to get accurate facts out.

http://www.mininggazette.com/news/2019/03/hancock-community-reaches-out-to-students/

 

[CWB1]

I too would be curious to know what defect lasted 30 years yet failed under a seemingly small amount of snow.

 

[Fuzzbean]

News photos and video show up to approximately 5 feet of snow on nearby remaining areas of the roof. We had a couple warm days that greatly melted and settled the snow, followed by a night of heavy rain. The rain saturating the remaining snow was no doubt the last straw. There had been an unusual number of collapsing roofs in this area in the 2 week period before this collapse, as the second-last blizzard we had was a doozy and the heaviest snow dump I have seen in years. The last blizzard, 4 days before the collapse, was more wind than snow.