[Greenbuilding] rigid or flexible? are there any lessons from the Japan earthquake for fastening residential structures to their foundations?

[Alan Abrams]

Yoshihiro Takishita describes how the massive, timberframed "gassho zukuri"
houses of Japan withstood tremors and storms--in which "the roof may become
deformed or shift slightly, but...It resettles naturally, since the tenons
are forced back into their mortises by the weight of the roof itself."*
Major beams were often selected from twisted and crooked trunks, to take
advantage of natural curves that were employed to enhance stability.  This
observation, however, hardly seems applicable to stud and joist
construction.

Nevertheless, Hugh Newell Jacobsen, an architect with a long and carefully
considered career in residential design, commented on how many vintage homes
in South Carolina withstood Hurricane Hugo, while new ones "literally
exploded."

"That is primarily because corners and rafters are just butt nailed, with
little to hold them except good intentions.  There's no diagonal, no
strapping, nothing to firmly hold.  And even with the technical design of
plywood skin to reduce torque and rack, *you can't wrap corners with it.*"**
[emphasis added]

By the same token, I recall photos of Galveston following the recent
devastating hurricane--showing near complete destruction of block after
block of residential neighborhoods, punctuated by the occasional surviving
house--which uniformly looked like construction subsequent to adoption of
wind resistant building codes.  This tends to validate Jacobsen, in that
connections between roof, floor, and wall assemblies had been taken into
consideration, resolving the essential flaw he identified.

All this to say that there is no place for an intermediate position--that if
we are building plywood skinned platform framed buildings--that we need to
follow all the way through with best practices or engineering for our
connections.

AA

*Japanese Country Style: Putting New Life Into Old Houses/Kodansha
**The Wood Book 1990/Hatton Brown


*Alan Abrams**
Abrams Design Build LLC*
*A sustainable approach to beautiful space*

6411 Orchard Avenue Suite 102
Takoma Park, MD 20912
office  301-270-NET- ZERO (301-270-6380)
fax      301-270-1466
cell     202-437-8583
alan at abramsdesignbuild.com
www.abramsdesignbuild.com



On Sun, Jun 5, 2011 at 12:31 PM, Kat <molasses at q.com> wrote:

>  I'd stick to the code.  It was revised/became more stringent after the
> Kobe earthquake and will probably change again in a few years based on
> analysis of the most recent earthquake.
>
> I've heard that ancient Chinese structures survived earthquakes because
> they were built without fasteners of any kind - my (non-engineer)
> understanding of that is the jiggling distributed itself throughout the
> structure at the joints, which were sort of lincoln-logged together.  I
> think the key there is NO fasteners, though.  None.  I'm certain that if you
> build a house the way we do now (all full of nails) and neglect to attach it
> to the foundation and we get a big earthquake you'll end up with a house
> that slides off the foundation.
>
> -Kat
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20110605/f7569445/attachment.html>