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12-story Wooden "Plyscraper" to Grow in Portland District

Posted June 23, 2017 12:00 AM by Engineering360 eNewsletter

The 90,000 sq ft structure will rank as one of the tallest timber high-rises to be built in North America. The building will be constructed primarily of cross-laminated timber components, in conjunction with glue-laminated beams and columns.


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Guru

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#1

Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/23/2017 8:37 PM

Yeah that sounds like a great idea....

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Guru

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#2
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/24/2017 12:03 PM

Our Province recently allowed 6 story wood structures.

I have the same sentiments with fire hazard.

Several times a year even wooden condos (2 story) burn up.

The really big fires are during construction - no drywall or sprinklers in place yet.

They are still trying to figure out how to have the fire suppression in place while it is being built.

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#4
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/24/2017 4:12 PM

Agreed. Just read about one in Firehouse magazine, only 4 stories, and in the incomplete configuration, framing in place but no sprinklers of other finishes, it made a huge blaze--lots of radiant heat damage to surrounding property and fire apparatus. Plus a construction crane fell over with resultant damage where it landed.

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#3

Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/24/2017 12:19 PM

It is possible, with laminated structures, to incorporate fire suppressants into the adhesive laminating process. As enough heat is applied, gases release that replace/combine with oxygen. I don't know the process, but know they were researching it years ago with commercial aircraft and shipping. As to the efficiency, no clue..

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#5
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/24/2017 4:16 PM

But doesn't release of suppressing gasses mean that the glue is degrading? Then, is it glue anymore? Thus leading to a collapse potential probability?

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#6
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/26/2017 10:46 AM

Yup, because as we all know... if it can go wrong, it will go wrong.
Problem with Grenfell Tower. the people doing the work, signing the cheques, signing off the work, buying the material etc don't actually understand the stuff they are dealing with anymore.
We are run by damn accountants and penny pinching is the order of the day.
There is no "common sense" anymore.
Everyone is too scared for their job to say "I'm not putting flammable insulation and cladding on a tower block!" And even if they did, some twonk with an MBA would probably sign it off...
Rest assured, those who were culpable will walk away scott free as usual...
Del

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#7
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/26/2017 3:42 PM

Not sure..I think the structural aspect also contains a great deal of mechanical fasteners...Could be wrong. Also, the thermal mass of wood prevents heat from concentrating, dispersing it outward and adding a lot of time before failure. In the picture above, The wood framing appears to be intact, while the aluminum sheeting caught fire..(?)

That is why gymnasiums and large span structures use various types of glue lams for girders, as steel only needs to get hot in one spot long enough to cause structural deformation, and ultimately, collapse. A demonstration was done using torches focusing on a glue lam and a steel beam, both of the same structural properties, with the glue lam not even being able to catch fire, while the steel beam utlimately got too hot, deformed and it's own weight caused it to fail.

Steel columns , in large buildings need to be insulated. Supposedly, the reason that the first tower struck at the World Trade Center , stood longer than the second one, was because during the construction phase, the first tower had asbestos insulation on some or all of the columns, and that practice was phased out for environmental reasons, and a "greener", but less effective insulation was used to finish the second tower. I have no first hand data, but only through 2nd hand info, regarding the cleanup at the sites. Google "Fire Engineering Site, "Fire Proofing at the World Trade Center, 2002, I believe. Also mentions shoddy application, missing material, etc.

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#8
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/26/2017 5:13 PM

Local 5 Story fire while under construction.

5 Story Condo Under Construction Fire

https://www.youtube.com/watch?v=fFg2wmgZzE8

Wood is safer?

Great Fire of London 1666 was attributed to wooden construction also.

Screw-ups are more frequent than anyone wants to admit.

This may be urban legend - but I thought one of the outcomes of the 1666 fire was the requirement for masonry walls ("cladding") and windows set back so the frames were not directly exposed to fire from below.

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#9
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Re: 12-story Wooden "Plyscraper" to Grow in Portland District

06/27/2017 1:55 PM

Yes, I get your point, but the important phrase is, "Under Construction". I can't tell from the video, but I am guessing all the studs and wooden framing is open and exposed to air, similar to kindling in a camp fire. From similar fires I have seen, many were started by plumbers using torches while soldering copper unions in water supply lines. The area of charred wood around the union wasn't properly dowsed by the Plumber before moving on to the next joint, and was left smoldering, unnoticed , sometimes into the night.

Now, take the same structure, and clad it with fireproof Type X, drywall on the interior, with non-flammable insulation filling the stud spaces which are fire blocked by code, every 4' or so, to reduce the air space. Now, over the exterior, apply 1/2 " or more, of shear wall, using plywood or similar material, and cover with stucco, and you have a pretty tight package.

Having done several residential fire restoration projects, the major problems are flames getting into open attics, with exposed bottoms of roof rafters and the tops of ceiling joists, flames being fed by attic and other vents . Most fires are started by flammable furnishings in the building, not the framing itself, with electrical fires or combustible agents engaged, such as candles, stove gas etc. Also, the use of PVC water feeds, and ABS vents, allow a flammable chase to climb through the structure, between the walls. Maybe they have corrected this chemistry by now. The inside joke is that the Fire Dept. is responsible for more damage than many of the fires, as their high pressure/ volume fire hoses, inserted through holes chopped in the roofs, windows and doors, actually blow the drywall right off he framing, and break studs when exposed! Full rebuilds.

I have seen video of homes in huge forest fires, where the heat around the structure gets so intense, that the homes virtually explode, due to the temperatures inside, without catching fire until after the explosion.

Anyway, would like to see more detail, as I am sure I don't have the full picture.

Thanks for sharing.

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