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Partial Mall Collapse 7

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dik

dik

Structural
Joined
Apr 13, 2001
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...from the Winnipeg Free Press, "ELLIOT LAKE, Ont. - A roof partially collapsed at a busy mall in the northern Ontario city of Elliot Lake on Saturday, prompting a local state of emergency and a search for anyone who might have been injured in the cave-in.

The collapse took place at the Algo Centre Mall a little after 2 p.m., at a time when the centre was bustling with weekend shoppers."

Dik
 
Interesting... PS hollowcore plank over steel beams and girders with concrete encased columns.

Collapsed just to the left of the Dollar Store. Is this an indicator?

Mike McCann
MMC Engineering
 
Supports for simply supported beams of whatever the kind in prestressed structures are sometimes not as good as required. I am always wary of small bearing support length for these items, that seem to go designed almost carelessly for malls where awesome amounts of people move daily.

Pushed by whatever the reasons, I have seen prefab buildings standing on no other lateral strength than the cantilever action of the colums (no shearwall, no bracing, no framing). Tooo much children's architecture, ready to fall by any movement.
 
Lets start with the assumption that the engineer design this building correctly and work from there for once and lets not assume it was incorrectly designed unless we have proof.

Too often I feel we go looking for the engineers mistake first, rather than taking all perspectives.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
 
One reporter noted that the roof had leaked for years and even a $1M renovation hadn't stopped it.

We can speculate all we want, but looks like a probable corrosion at a connection issue, since the beam appears to have failed on one end. Both design and construction (except waterproofing), could have been proper....just failure to resolve the waterproofing issues and maintain the building...but then, was it maintainable?! All questions for the ensuing litigation.

Hope everyone was OK.

I assisted my former business partner in the investigation of the collapse of the roof of a Sears Store in a mall in St. John, Newfoundland in the '80's. That one had a reason....high snow load and some fabrication problems with the open web joists. It also had some warning...the ceiling tiles started to droop, then a pop was heard....the security people cleared the store in less than 5 minutes and as the security guard was opening the door to leave as the final person there, the roof caved in. He was thrown through the doors but not injured.
 
...from Reuters, "Four people are injured as the roof of a shopping mall in Canada caves in. Paul Chapman reports. "
 
I do not use hollow core for exposed conditions. Its superb for interior spaces (hotels, apartments, offices) but for garages, and roof conditions it poses a problem for tracking down leaks. I prefer solid plank for those applications.
 
In any case the deficient designs I refer to come from customary practice of tight support, this coming from required economies as historically mandated directly by the owner or as an effect of greed and cut throating competition.

So I am not specifically blaming designers, but what in my understanding has sometimes become sanctified practice of too little support or restraint. Even if hidden by the technics, it is our work to find sound structural proportions able to once and for all bar these failures that sparsely occur.

The failure being at an end, it suggest a support failure.

I am also wary of ANY "1 million dollars" or whatever reform. It is also well proven that lot of times reforms damage the structural systems and then it has not been corrossion but -who knows if criminal- negligence by some party what has caused the failure.
 
ishvaaag,
To start off on a discussion about a failure as though it is possibly due to negligence on the engineers behalf does nothing for the engineers as a group. Sure you can say this is something your aware of with about this construction, but lets be realistic, you have never been to site, you are working off one or two photos and a few reports. You really have no idea about the building at all in regards to structure, foundations ect. I think it is self destroying as an engineer to start the discussion as thou the engineer is as fault. I think it would be better to start with a more open mind and realistic review of the situation.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
 
Hard to reliably tell from the photos, but it does look like there is corrosion at the beam connection. Not surprising since the collapsed roof was used for parking and I would expect corrosion due to the de-icing chemicals tracked into the garage, if the waterproofing membrane was leaking over a long period of time and not repaired. Newspaper reports talk about mall occupant complaints about leakage. The rate of corrosion increases with increasing temperature so the recent spate of very hot weather may have hastened the failure if it was corrosion related.

Really drives home the tremendous responsibilities on structural engineers when designing and trying to convince owners that inspection, maintenance and repair is required over the life of a parking garage. It has never seemed right to me that the owner, who may have not more than a grade 9 education, can make the decision of whether or not to carry out the engineer's repair recommendations, even though the public safety is at stake.

Although I would not use precast hollow core slabs for parking garages, I think it would be incorrect to conclude at this stage that there was a design error.

Very sad and tragic that they have had to discontinue the search because the structure is deemed unsafe, even though they hear tapping from the rubble.
 
Frankly, the loss of these people allows for my insistence. I don't blame any party in particular of the toll, nor I am starting any discussion leading to blaming engineers for failures in buildings, people in general has seen the connection even from Hammurabi times when the case is, so please, I am simply remarking that design of prefab structures in my view has gone too short on support. With the complex structural codes of today, one may spend too much time looking the tree and not seeing the wood.
 
The BBC had initially indicated that as many as 30 people were missing. This has been reduced down to 9.

Interesting that the emergency crew is expecting the owner to provide an engineering report to safely gain access and has stopped operations because it is dangerous without this.

A couple of years back I sent a letter to the PEO (prof assn). when there was a death caused by a masonry washroom wall collapse. With the stage collapse and now this, I think it's time to send more correspondence. We are charged with safeguarding the public... and we seem to be failing.

Dik
 
I trust that we are all applying our experience and wits to a few grainy photographs as a forensic exercise, subject to future discovery. No need for anyone to get sensitive about it. If we start with the assumption that it was not an engineering failure then we really haven't taken all perspectives have we?
 
Received the following from one of the engineers in our office, "Time and time again we get told do the cheapest construction thing now as maintenance will take care of any issues in the future.

Yet time and time again we witness things falling apart because of a proven lack of maintenance."

CAB:
I haven't stated it is an engineering problem, but it likely is... either from design, materials, corrosion, or whatever.

In any event the professional associations (around the world) should be involved if there is a collapse and a member of the public is affected.

Dik
 
Personally I think you should follow the evidence trails and see how the paths layout before any assumptions are made. Having been involved with many investigations of late into failed structures due to wind loadings and floods, I can tell you now that often what seems obvious reason for failure, is not quite so the case.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
 
I agree with dik. I have had the same experience in my engineering career. Other than engineers, people do not appreciate or want to pay for durability in the design. The design is driven by architectural appearance and initial cost. Durability is way down the list, if it appears on the list at all. Irrespective of the cause of this collapse, there are plenty of other cases where no, or inadeqaute, attention was given to durability and then the structure became an unending and disruptive problem.
 
dlk's "Time and time again..."

I eventually closed my practice rather than gypo, and went to work for a 'dark side' D-B property developer as in-house engineer. I found it's not the developers, it's the contracted A/E's and GC subcontractors! The looting!! The looting!! One structural hit us for $500,000 in fees, and said to my face, "Don't worry about the (85% design submittal marked 'For Construction'), we'll take care of 'minor' design-detailing changes by CHANGE ORDER." Not for $500,000 in design fees we won't!!!

I found at least 20 lapses, a total lack of detailing, but all they'd give us to review with was the bulk computer printout, yet they were able to get a construction permit from the City B.O. with that 'engineering submittal'!! So we had to pay them for 'construction ready plans', then fire them from the CM portion of the project, ...but sure enough, we had to BUY OUT their CM contract portion.

Then GC subcontractor CO gouging ... O...M...G~! In the historical accounts of the Mortgage.Con, when we sit by the fire, nobody will ever know how many lives were saved from shoddy D-B gypos by that 'untimely' end to the Great R/E Bubble. I would never buy any property built in the 2000s.

Now it looks like a whole generation of graduating engineers will be lost.
 
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