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Re: Effects of the New Code on Wood structures - good or bad?????-Part 1[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?????-Part 1
- From: Charles Greenlaw <cgreenlaw(--nospam--at)speedlink.com>
- Date: Thu, 22 Jul 1999 21:23:03 -0700
Dennis, this is one of your best postings ever-- well reasoned, cool headed, and concise. Not only that, it answers the question knowingly and on point. And, the questioner has some excellent points, which were respected. I too do a lot of residential work and I find, as you state in your third paragraph, that irregularities, indeterminacies, and imponderable load paths are the rule. Engineering complexities indeed are exponentially grown from what a DSA Classroom or rural Telephone Company equipment building pose to an elite-firm SE designer and Seismology Committee member. I've been there on all of those, including for the entire 1981-88 Blue Book rewrite's wood section. Residential was given no concern whatever back then, and I doubt it's got much in Seismology since then. Not from anyone who understands it, anyway. Yet I find residential the most challenging and satisfying to model and to economically design for, especially for the personal touch it takes. It's like the difference between shooting ducks with a shotgun and shooting Tomahawk missiles by GPS preprogramming or terrain map following: more by eye and judgment than by continuing electronic recalculation. There is a difference in money resource expended as well, and apparently a different form of personal appeal. Much of the present conflict, I submit, is from the "precision aiming" SE community insisting on control not just of their own high tech stuff, but also of how bird gunners operate, so to speak. You know, radar-aimed 12-gage fire control and all the rest, while out in a swamp. There WAS a good cadre of residential practitioners in a mainstream SEAOC committee, namely Central Section's Code Committee in the early 90's. But there was none of that sickly sweet "compulsory consensus" with the other three SEAOC Sections on residential, and the house framing turf was taken away from Code and given to Seismology where nobody would make any fuss. The late Ajit Virdee told me this would happen, and that the Section veto would be eliminated from SEAOC Bylaws. I spoke at length with past SEAOC Code chair Norm Scheel the other day about 97 UBC as affects residential, which he also does a lot of. He is just as disgusted with it as I am, and so is local Code chair Doug Krug, who checks as well as designs residential. So much for only the stay-away's being upset. Ed Workman's remarks were completely correct, perhaps well beyond the extent he has actually seen. We need more dissent being aired, not less. Too bad about the acrimony and divisiveness, but the situation has gotten so far out of hand, and so abusive by "professional code changers" who pulled their power plays when they had the chairmanships, that a huge amount of ill will already exists. SEAOC has absolutely abdicated its duty to represent the more silent majority of its constituency and see to their interests. Fair notice was given long ago and scoffed at; now comes the furor, inevitably as it must. Charles O. Greenlaw SE Sacramento CA At 08:53 PM 7/22/99 EDT, Dennis Wish wrote: >Mark, the answer is very simple - none of these provision were either >applicable to wood framed construction with wood diaphragms until 1988 and >none of them were either enforced or consider the "Standard of Practice" for >wood framing until this code cycle. >The actual reason is not known just why the provisions were not enforced >prior to 1997 UBC but it is suspected that it was because there was no >rational means to calculate the deflection of a flexible diaphragms (and >there is only a multiplier suggested by APA at this time) and the provisions >in the code could not be satisfied. > >Why all the ranting and raving as you put it? The code rationale is very >straight forward if you are dealing with a simple geometric shaped building >with a great deal of simplicity in the diaphragms and transfers of shear from >floor to floor. This is typical of most commercial and industrial projects. >It may even be somewhat easier considering a simple small residential >structure that is fairly rectangular with few irregularities. >Once you get into the design of a structure that is neither rectangular, with >multiple levels offset from one another (such as split levels), roofs that >frame upon one another or diaprhagms that cantilever and any other creative >avenue that the architect dreams of, the design difficulties grow >exponentially. > >Now if you reread all of my posts, you can begin to see the difficulty that >this creates for almost all of us who specialize in wood. Most of us feel >that the ends don't justify the means - there is not sufficient evidence to >justify the change nor is there sufficient damage attributed to justify my >rants (I don't rave about this code). > >I will review part two and respond. > >Dennis
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