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10th February 2018, 11:49 AM #16
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10th February 2018, 01:02 PM #17GOLD MEMBER
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Canada uses more engineered wood products than you can imagine. Prestressed engineered Glu-lam beams will span useful distances.
The University of Northern British Columbia has a 6 storey research division, all engineered wood.
The atrium in the local Prince George hospital can't be more than 5-6 stores tall but all engineered wood from the ground up.
It's really warm-looking and interesting geometries in the post and beam design.
". . .as strong as steel." In what ways? Show us all the real numbers, both mechanical and non mechanical properties.
Density isn't a good predictor of elasticity or most anything else but density.
You're right = indoor or otherwise sheltered apps are common. No way I could see that outdoors here.
This year, we swung from +47C in the shade to -30C last night.
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10th February 2018, 04:10 PM #18
Re Artmes comment about us having a long way to go to catch up with overseas re laminated beams etc.
We had a plywood company here in Sydney which had 2 huge clear span factories constructed 60 or 70 years ago with laminated beams. Both have been replaced with home units for the masses.
I bought some 3/8” formply from Symonds for a formwork upstand from where Wentworth Point now is.
I vaguely remember driving into their factory a 100’ wide at least and as I got out of my ute realised the huge curved beams were laminated timber.
My ply was about 30’long so they just rolled it up, tied it with some rope in the ute.
When I cut the rope back in my ‘shop it uncoiled very promptly.
Briggs was another local ply company doing interesting stuff with Coachwood ply for the Mosquito during WW11. Their early efforts with the Pom glue made from curd fell apart due to humidity, they ended up using urea I think.
H.Jimcracks for the rich and/or wealthy. (aka GKB '88)
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10th February 2018, 04:23 PM #19
Oz lam buildings.
Bit more info re how dumb we are compared to the rest of the world.
My first post I just did from memory which as you all know tends to get foggy after 70.
If you’re interested google Ralf Symonds.
Here’s some info on the St Peters factory.
H.Last edited by clear out; 10th February 2018 at 04:25 PM. Reason: Typo
Jimcracks for the rich and/or wealthy. (aka GKB '88)
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10th February 2018, 10:47 PM #20Taking a break
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All structural plywood has to be "A-Bond" (phenol formaldehyde resin) to comply with Australian Standard, which is a waterproof bond rated for long-term full exposure. As long as the beams are able to dry fully after rain they are most likely going to be fine.
Source: http://ewp.asn.au/library/downloads/...lvl_design.pdf page 253-254
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10th February 2018, 11:23 PM #21GOLD MEMBER
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taken from Elan's link.
Note:Even though the structural plywood phenolic bond is durable, the plywood will only beas durable as the timber species from which it is made. If the plywood is going to beused in weather exposed applications or under other exposure conditions of severehazard, the durability of the timber veneers must be considered and the plywoodpreservative treated if required to meet the hazard requirement.
I also thought there was a structural B bond made from melamine urea but that article made no mention of it.
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10th February 2018, 11:33 PM #22Taking a break
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B-Bond is waterproof for short-term exposure and is allowed in exterior ply, but it doesn't comply with Australian Standard for structural plywood
Library - Tutorials
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11th February 2018, 03:26 AM #23GOLD MEMBER
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I wonder what sort of fire ratings the glu-lam beams have.
Seems they would char on the surface rather than soften and sag.
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11th February 2018, 04:08 AM #24
There was a new building at Barangaroo Sydney which is a multi story wood building using laminated beans and apparently it was rated as highly as a steel building. Let me see if I can find the article.
Edit: here we are: https://www.google.com.au/amp/s/amp....15-gqsmrn.html
Plyscrapers!
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11th February 2018, 04:27 PM #25
I was thinking that for this new engineered timber to be as strong and dense as steel it would have to be made from hardwood: Not because of the inherent density or strength but because of the pored characteristic of so-called hardwood, which in botanical terms should be called pored wood or non-pored wood (for what we tend to think of as soft wood).
Balsa of course still fits into both these categories but pine does not. My thinking is that the tubes of the pored wood are better suited to become the receptacles for the additives, but perhaps that is not the case and the cellular walls absorb the enhanced properties.
Regards
PaulBushmiller;
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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12th February 2018, 10:55 AM #26Skwair2rownd
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One of my problems with LVLs is that when decking is nailed to it the laminations can be parted by the ingress of the nails.
This presents an opportunity for water to penetrate anse the process of rot in motion.
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12th February 2018, 11:15 AM #27GOLD MEMBER
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The porosity of the hardwoods, the angiosperms, has many qualitative differences.
Is the timber ring porous or diffuse porous? Look at the modulus of elasticity.
As for absorption, look for the vessels being occluded with tyloses.
This explains the exclusive use of the white oaks (Quercus alba) for barrels as opposed to any similar use for the red oaks (Q. rubra).
In addition to the vessels of vessel elements, there will be a species-variable mass of very thick walled xylem fibers.
What is less evident is that the xylem fibers are far shorter than the xylem tracheids of the "soft woods," the gymnosperms
and the conifers of economic importance. This is crucial to 'web-strength' with in the wood laminates themselves.
One result is that engineered wood products from conifers have excellent performance characteristics in wood design.
The longest individual conifer fibers can be as much as 3mm in length. These are found in white spruce (Picea glauca)
and Englemann spruce (P. englemannii) in the central interior of British Columbia which is a cool - cold climate.
Any conifers grown in much warmer climates ( your Monterey pine (Pinus radiata)) lacks some suitability because the fibers
don't grow as long as in cooler climates.
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12th February 2018, 01:00 PM #28Intermediate Member
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12th February 2018, 01:30 PM #29
This is all creating quite some press (haha!)....it's now on Slashdot and Nature https://www.nature.com/articles/d41586-018-01600-6
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12th February 2018, 02:49 PM #30
Thanks WP
And here's a reference to the full article in Nature, a highly respected journal. Unfortunately you'll have to pay to get past the Abstract:
https://www.nature.com/articles/nature25476
Cheers
Graeme
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