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Re: Effects of the New Code on Wood structures - good or bad?????

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I did not mean to imply that the new code is promoting more flexiblity or 
less capacity. This is not the case. In fact it does promote more capacity in 
the walls of larger, multi-story structures where the difference in capacity 
due to torsion become greatly enhanced as you approach the first level.
However, for smaller structures two stories and under, there is little 
significant change between the two methods other than to make the engineer 
aware of the relative stiffness between elements (much the same as in masonry 
or concrete). 
The ability to do something constructive about the difference is really a 
moot point since this will greatly depend upon the skills of the contractor 
in the field to more closely adhere to the working drawings.
Residential construction of tract developments (meaning that this will have 
more effect upon middle and lower income homes) are more closely tied to 
profit margins and making homes that are low enough in cost to "hit" the 
market that can afford them. The more labor involved (which I believe to be 
more costly than materials) will rise as production becomes slower and cost 
per panel installation increases.

Therefore, my point is that the advantages do not outweigh the disadvantages 
of cost and the potential to force the developer into a less than acceptable 
prescriptive method.

You are right that many of us will need the time to run the numbers in order 
to draw these same conclusions. I have done this and it is the reason for my 
strong objections. Yet, I can't help but think that it should have been 
Seismologies responsiblity to thoroughly investigate the effects of this 
method on wood structures rather than simply lump wood into the same vat and 
expect everyone to comply. Residential wood design is much more involved than 
most engineers give credit to. The architecural aesthetics are more demanding 
- geometrically - than commercial or industrial buildings. 

As per your comments about how a diaprhagm will behave - you may be correct, 
but I am confident that most of you will find that it simply does not matter 
unless you try to design an open from structure with no support or try to 
push the limits on panel H/b and load (ie, approach a 2:1 aspect ratio at 
1100 plf). 

Still, the new code does not help us understand how to work in the newer 
proprietary shearwalls on the market. Since most of these represent emperical 
studies, there are few numbers that can be manipulated to predict the 
stiffness of these systems. this leaves us in a state of Limbo until either 
the manufacturer or Seismology can advise us as to the best way to address 
the design problem with proprietary systems. 


In a message dated 7/22/99 6:06:55 AM Pacific Daylight Time, 
jwatson(--nospam--at) writes:

<< What is the formal process for making changes?  Secondly, does anyone
 have a better system?  We can all yell and scream all we want, but until
 someone has a better method we are stuck.
 Jake Watson, E.I.T.
 Salt Lake City, UT >>