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Re: Effects of the New Code on Wood structures - good or bad?????[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Effects of the New Code on Wood structures - good or bad?????
- From: Seaintonln(--nospam--at)aol.com
- Date: Thu, 22 Jul 1999 14:25:59 EDT
Jake, 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. Regards Dennis In a message dated 7/22/99 6:06:55 AM Pacific Daylight Time, jwatson(--nospam--at)inconnect.com 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 >>
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