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RE: 10 story wood building

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A good example of the structural use of bamboo is the building scaffolding used in Hong Kong.

Bob

-----Original Message-----
From: David Merrick, Structural Engineer, Merrick Group [mailto:mrkgp.se(--nospam--at)gmail.com] 
Sent: Thursday, March 10, 2011 8:47 AM
To: SEAINT
Subject: Re: 10 story wood building

This subject referred to the article

http://www.forintek.ca/public/pdf/Special_Pub_Order_Form/SP52CrossLaminatedTimber_the%20boook.pdf

The 10 story project is a flag ship to promote uses to cut down soft 
wood forests. Increasing strength with fiber orientation and glue.

With out the "cross-grain crush-able zones" the shrinkage is not as much 
of a problem, but the assumed wood redundancies and ductility are lost 
and need to be removed from the design guides for those type of wood 
structures.

Dynamic analysis of wood framing results in high periods and lots of 
ductility witch greatly reduces the seismic base shear for a wood 10 
story building. But so it does for the two story building. Wood design 
guides assume one is not performing a dynamic analysis. Or do they? 
Technically the code does not disallow reduction of base shear by 
dynamic analysis for wood framing.

Green? Why not Bamboo?

Fast or slow growing trees have a wast of 20% for the woody roots lost 
when harvested and returns the carbon to the air through decay.

Harder woods even have a higher strength when used in manufactured 
members. The ratio of strength to years to grow are probably close to a 
constant.

Hard woods take 30 years, soft wood 10 years well...but bamboo takes 3 
years. After the die off, bamboo roots survive to grow the next harvest. 
Bamboo is much stronger than most evergreen tree products, hard or soft, 
and so will be the manufactured bamboo fibers and glue systems.

I would rather see our forests remain to develop into old forest growth 
and I eager to see start ups of bamboo farms and added bamboo wind-rows 
for other farming uses. Bamboo grows in cold regions and alternatively 
can be used as light weight poles for fencing and temporary construction 
shoring.

Because of the future competition of Bamboo products, If Canada and US 
want to promote harvesting of our forests, they would be better off 
focusing on whole cut timbers. Today corporations are starting 100,000 
acre farms around the world. China exports bamboo plywood and 
manufactured beams of bamboo, albeit, for now, for boutique green 
purposes that keep the prices high.

Fascinating is that specific bamboos, every 100 to 200 years, will 
simultaneously bloom and then all die, saving the root, leaving 3 years 
of no product. They all do it together, no matter how far apart or 
variant the climates. No product for about 2% of the time. It has been 
theorized Asia plagues may correlate with these dyings as new housing is 
stopped for 3 years and the bamboo fruit feeds the rodents.

New bamboo shoots achieve a complete mature length and diameter in 3 
months and then reach a maximum strength in 3 years. This assures 
continuous shade and wind protection uses.

I watch truck loads of our forests as manufactured construction elements 
to be used for our wood designs and wonder why is that not of bamboo?

David Merrick



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