Vancouver B.C. Rooftop Parking Collapse

Question

Vancouver B.C. Rooftop Parking Collapse

Sym P. le (Mechanical)

(OP)

15 Jul 22 01:30

CTV News - 2 in hospital after rooftop parking lot in East Vancouver collapse
CBC News - 2 taken to hospital after rooftop parking deck collapses into office in East Vancouver

When I heard the news on the radio earlier today, that a rooftop parking structure in East Vancouver collapsed, my mind immediately went back to an incident in the mid 1990's when a loaded concrete truck punched through an elevated structure, landing on it's ass end in the business below, knocking the driver unconscious. It turns out to be the neighbouring address, however, everything about the development screams that it's the same ~~owner~~ development.

The earlier incident occured in part because the height limitation frame at the parking entrance had been removed to facilitate renovations. The concrete truck driver didn't get the message. I notice in Google Street View there is no equivalent warning structure at the entrance to the 3438 address. WorkSafeBC better be all over this.

Google Earth view of 3434/3438 Lougheed Hwy., Vancouver, B.C.

3434 Lougheed Hwy. - Site of Today's Incident

3438 Lougheed Hwy. - Site of Mid 1990's Incident

Sym P. le (Mechanical) · Answer 1 · 2022-07-15 02:23:08

If they were re/re the roof membrane and there was a layer of sand isolating the existing membrane from the asphalt paving, it appears, they were consolidating the material for removal. The evident pile in the background is distributed across many precast concrete T-beams however, adjacent to the failed zone, there appears to be the remnants of another pile which may have run in line with the length of the T-beams.

spsalso (Electrical) · Answer 2 · 2022-07-15 03:25:33

"...everything...screams that it's the same owner."

Does it also scream it's the same designer and the same structural engineer?

spsalso

Sym P. le (Mechanical) · Answer 3 · 2022-07-15 03:52:32

Yes however, the original designer and structural engineers are not likely choreographing the maintenance work. If the project manager screwed up on the first incident, maybe they should have been more aware on the second go around even if it is 25 years later. Someone has to catch on that there are inherent precautions required to work on elevated structures accessible to heavy equipment (even if it's the lite version of same). It's just plain recklessness to maim and injure people again and again.

human909 (Structural) · Answer 4 · 2022-07-15 03:59:16

Agreed. Thanks for posting this. And interesting though very much avoidable failure. Who know in 25 years the owner might have changed.

I've never really considered or dealt with elevated drivable structures before. I support a very sturdy height barrier with strong placarded warnings against removal might be one approach. The one on the other address looks very flimsy and still doesn't seem like a great deterrent to removal and still has a pretty decent height to it. I'd expect a lower height limit simply to limit inadvertent entry from overweight vehicles.

Sym P. le (Mechanical) · Answer 5 · 2022-07-15 04:31:17

Note that we seem to have a local problem with elevated parking structures. Not even three miles away is the infamous Save-On (Cave-on) Foods debacle from 1988.

Sym P. le (Mechanical) · Answer 6 · 2022-07-15 14:51:53

Apparently they were using the rooftop parking area to stage fill/top soil material from the rooftop green space during reroofing.

CityNews

spsalso (Electrical) · Answer 7 · 2022-07-15 17:16:17

Interesting photo, that. I was wondering how far the "building" went, out towards the road--farther than I thought. Comparing to an overhead view, it looks like it went beyond the parking area, and under the "dirt".

It will be very interesting to see how much "dirt" was piled on the area that fell. And to compare its weight with what the deck should have held. Since there doesn't look like an obviously safe place to store it on-site, moving it elsewhere would have added a lot of expense. Justifiable, obviously.

spsalso

dik (Structural) · Answer 8 · 2022-07-15 17:50:21

...and the professional association is strangely silent.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Sym P. le (Mechanical) · Answer 9 · 2022-07-16 00:17:10

RE: Vancouver B.C. Rooftop Parking Collapse

Sym P. le (Mechanical)

(OP)

16 Jul 22 00:17

There's the skid steer and a pile of dirt.

Sym P. le (Mechanical) · Answer 10 · 2022-07-16 16:16:58

Images of the concrete truck incident from 1996. The neighboring structure is steel truss design as opposed to the precast concrete T's used in this design. It's still disturbing to see these two incidents on adjoining properties/addresses.

Global News

JLNJ (Structural) · Answer 11 · 2022-07-18 13:12:15

I think our parking garage design live loads are too low.

Heck, I thought 50 psf was too low and then we lowered it to 40.

Answer 12

[Post Deleted]

dik (Structural) · Answer 13 · 2022-07-18 19:26:37

JLNJ... In a really well designed parking garage, a vehicle takes up about 300 sq.ft, not much less when you consider the isles, ramps, entrance, and exits. That gives about 300x40 or about 12000lb/vehicle... On a 18x9x40 that gives about a 6480 lb vehicle per stall... The average weight of a car is about 4000lbs... 40 seems to be an OK number... For alternating loads, I used to use LL = 25psf and 0 psf to determine max +ve and -ve moments when I used to design them... haven't done one for decades.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

FacEngrPE (Mechanical) · Answer 14 · 2022-07-18 22:05:04

The uniform load of a vehicle is applied to spots with a contact pressure approximately equal to the tire pressure. You can pass the uniform load criteria and badly fail the contact pressure requirement. The result - either immediately or after a while can be in punch through failures.

It is always something to check.

dik (Structural) · Answer 15 · 2022-07-18 22:24:18

It's been decades since I looked at point loads from tire pressures and in past they were never close to determining the failure envelope.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

FacEngrPE (Mechanical) · Answer 16 · 2022-07-19 00:43:28

Perhaps I am a bit sensitive to the issue. When your employer has some of these monsters running around the plant you find that standard precast concrete DI structures suitable for HS20 loading have limited service life. Failure mode is the casting punches through the concrete.
Concrete mixers are not this heavy, but they also push the loading envelope.

Credit https://www.hyster.com

Sym P. le (Mechanical) · Answer 17 · 2022-07-19 02:19:24

Both of the structures seemed to be doing fine under normal circumstances. Maintenance projects blew the budget.

dik (Structural) · Answer 18 · 2022-07-19 03:15:30

That's a whole bunch different than a parkade... I wouldn't park a 747 in a parkade, either... That's an industrial floor design... a whole bunch different.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

dik (Structural) · Answer 19 · 2022-07-19 06:31:22

Another key issue with parking structures is that you have to be very careful about expansion joints... they have to be good and they have to be properly located. Also whatever coatings, if any, you intend to apply.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

hokie66 (Structural) · Answer 20 · 2022-07-19 06:57:36

This was likely due to overloading, but the thin flanges of those precast tee sections bothers me. That, and the way the members are connected together, or not.

dold (Structural) · Answer 21 · 2022-07-19 15:28:00

Quote (FacEngrPE)
The uniform load of a vehicle is applied to spots with a contact pressure approximately equal to the tire pressure. You can pass the uniform load criteria and badly fail the contact pressure requirement. The result - either immediately or after a while can be in punch through failures.

My understanding of the 40psf uniform, 2000lb point load on 4"x4" patch is to simulate a car jack, not the tire contact patch. But I suppose the tire contact patch would be roughly the same size and force. Seems less likely though that a tire would punch as easily as a jack.

Lomarandil (Structural) · Answer 22 · 2022-07-19 19:43:25

Tire contact area is somewhat higher -- 10"x20" for a design semi-truck, maybe as low as 4"x6" for a passenger vehicle.

2000lbf over 4"x4" (the jack load) is 125 psi, and nobody runs automobile tires inflated that high.

But yes, loaded forklifts (or wheel loaders) are a totally different animal and require additional consideration.

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Vancouver B.C. Rooftop Parking Collapse