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RE: rho

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I wrote Martin  privately a LONG letter which I don't believe is appropriate
to post. Only because I made some comments in another post that he took
objection to. I wanted to disclose my sources to Martin but don't feel I
would like to expose the those I mentioned without names to unnecessary
ridicule when their intentions may have been more honorable.

In short, I believe it was Buckminister Fuller who indicated that we
overspecialize ourselves into extinction (a simple paraphrase from his work
called Spaceship Earth as I recall).

Henry David Thoreau also believed in the philosophy of "Simplify, Simplify,

One flaw in the rational is that we know there is an inherent factor of
safety built into most formulas for the design of bending failure at working
stress levels. While there is always a chance that a defect or other act of
nature could cause failure at one once over maximum load, most of realize
that the code is not that close a call unless, possibly your designing to
ultimate strength methods - which few engineer designing wood structures
would do.

Statistical verses Probabilistic is, as Martin suggests, "weird" which
implies that we are attempting to over-specialize our talents and as I
summarized to Martin separate, we fail to recognize the pragmatic - that
which is the most practical solution when considering the alternatives. In
this case, the alternatives is the allowance to remove enough irregularity
in a wood frame structure to allow the builder to eliminate the engineer and
architect. Now, maybe the City of Los Angeles's Andy Adelman has suffient
power in the building department to disallow UBC 2320 (although at the 1999
SEAOC Convention Andy was still concerned about the provisions), the rest of
smaller municipalities are at the mercy of the builder and the local city
council who view the code as a layperson would - without actual knowledge of
the difference between methods which we all know is significant. Pressure is
placed on the building official who must be able to find some lawful excuse
for why the home is disallowed to comply with this prescriptive section of
the code.

Maybe others can speak of their experience, but mine has been one of
increased "bashing" of the engineering community by developers and builders
of homes in the low to middle income range. A homeowner is more likely to
accept his builders suggestion to save thousands by eliminating the engineer
and architect. What do we end up with when the home is not only less than
the minimum standard established by the full compliance codes, but more
importantly a home constructed to lower quality and within 2 to 4 Kilometers
of the San Andreas Fault in Riverside County.

What it comes down to is that we are replacing common sense with the need to
prove pure science and the value of a Probability study to ascertain risk on
a home. This will be moot as the NAHB-RC with the support of most wood
organizations gains support for perforated shearwalls.

Even more, it has already gained ground as the Aas verse William Lyon
company California Supreme Court decision (actually the Superior court)
excludes all evidence of code violations and non-compliance to the
construction documents as an unfair advantage to the Plaintiff in a case
where damage or Injury has not YET occurred. What is the purpose of the code
if not to protect from the potential hazard that we have believe has
justifiable Cause and Effect.

Enough, think about this for a while and then forget it.


-----Original Message-----
From: Martin W. Johnson [mailto:MWJ(--nospam--at)]
Sent: Friday, February 09, 2001 1:04 PM
To: seaint(--nospam--at)
Subject: Re: rho

Sorry Dennis, but I didn't say "statistical studies" I said "probabilistic
design method", something which is quite different.  Fundamentally there are
several approaches to design.  There is "rule based design" which is what
sprinkler designers use.  There is "deterministic design" which is what you
I know and love.  And there is "probalistic design" which is, to my mind, a
somewhat wierd way to approach design that assumes that anything could
potentially fail under any load, but what is the risk?  While you and I
calculate a load capacity of a beam and perceive that in theory one ounce
greater load could induce failure, probalistic designers perceive that if
tested a hundred or a thousand beams you could develop a curve which would
define the risk of failure for that particular situation.  It is used in the
nuclear industry to quantify risk and represents a fundamental basis of the
design approach, which is something else which we sometimes love to hate.

By the way, when I said "bashing" I was being somewhat tongue-in-cheek.  I
I know, I should type a silly happy face when I do it, but I refuse to type
darned things.  If I could communicate more clearly I would not need such
things, it seems to me that typing them is like giving up on language.