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Re: Rigid vs Flexible residential diaphragm discussion

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Chris,
The physics of fluid mechanics and thermodynamics are fairly well set in 
science. The application of such theories takes into consideration variables 
such as the smoothness of the pipe and much more (it's been a lot of years 
since these courses). The construction of pressure vessles and pipes is, in 
my opinion, much more controled than the work done by contractors on 
buildings in the field. 
The problem is that the code tries to make uncontrolable variables fit neatly 
into a theory of physics that can only be predictable if all variables are 
accounted for. Furthermore, the complexity of the model is unquestionable 
compared to manufactured items such as vessles and piping. The difference is 
in the skill of the laborer who impliments the plan.
This is not the problem originating in the engineering community, but are 
better controled in certain types of construction practices that historically 
required higher skilled labor.
We have gone through the history of wood construction and only in the last 
few years have realized it's importance, not as a threat to life, but as an 
ecconomical threat to our society by subsidies from goverment to ease the 
owners suffering and by the outlay of insurance which exceeds (they would 
have us believe) the cash pot and therefore not leaving them suffient money 
to invest. 
My point is that unless the construction industry is revamped to improve the 
capability of the persons building a structural system, our profession can 
not insure predictability except in the perfect state as to how it should 
perform. Even if the liability is not in our offices (assuming we design and 
detail properly) the faults of the legal system will drag our butts into 
court and cost us thousands to prove our inocence. This either comes from our 
pockes or from an insurance company again.

I can not fathom why the construction industry, who has been proven in wood 
construction to be defiecient in implimentation of the plans, fails to 
promote minimum education or certification for those who build structural 
systems. There should be some understanding of the basic wood framing 
principles of load path - even if it is only from Conventional Prescriptive 
methods. As far as I know, there are no questions on the licensing exam that 
help determine a contractors knowledge of the basic prescriptive methods that 
do not require engineering or architectural skills. In my experience, these 
are the areas that are deficient or incorrect in construction that are not 
caught by the building inspector or corrected. 

I think that this is the discontinuity between professions that has, 
historically, been insurmountable. I know that this is the primary reason why 
wood systems will never be predictable on a level compliant with SEA's Vision 
2000 until construction quality is addressed and controled.

Dennis S. Wish PE

In a message dated 8/9/99 8:20:02 AM Pacific Daylight Time, 
chrisw(--nospam--at)skypoint.com writes:

<< One thing stands out--no one is arguing either way on a particularly 
 scientific basis, either citing research results or scientifically 
 assessed personal or service experience ('we've always done it that way' 
 or doesn't count--no way to distinguish luck from skill). That's a sure 
 sign that someone, somewhere hasn't done his homework. One thing's 
 certain--a construction code that can't guarantee satisfactory 
 performance and be used and enforced, makes the laity unhappy, discredits 
 engineers and makes structural engineering more sorcery than a 
 profession. Writing structural codes is a big job, but if the structural 
 engineer won't take the time to codify their practice, you can bet the 
 courts will. 
 
 One other thing makes me curious--where is the ASCE in all this? Judging 
 from the UM collection they have a body of research that is second to 
 none. How is it that everyone quotes trade associations and manufacturers 
 and no one cites the ASCE?
  >>