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- To: addseaoc(--nospam--at)euken.com
- Subject: Fwd: floor deflections, was: Re: building code minimums for wood frame
- From: rlewis(--nospam--at)techteam.org (Richard Lewis)
- Date: 30 Jul 1997 14:32:52 GMT
>General comments to the many opinions raised about the issue of "code >minimums"... >Although I'm not an attorney, I don't believe that a client can >successfully sue an engineer for designing above code minimums >particularly if the design engineer can prove that his design was >warranted by calculations, etc. For example, the code requirement for >live load deflection is L/360. Based on my experience, this criteria >will produce a "soft" floor in a residence with long (>18') spans. My >preference is to use L/400. I cannot even conceive a qualified expert >witness being able to successfully debate this issue. My experience in floor performance is that even for spans greater than 14', a L/480 deflection criteria is not desirable especially if there is not sheet rock on the ceiling or any loads on the floor such as furniture to dampen the vibration. A while back I specified 9-1/2" TJI/25 at 16" o.c. for a 14' span which exceeds L/480 and in hindsight I felt it was a bit bouncy. For custom homes in particular, this is an issue. An owner may never know the difference unless it is brought to their attention, then it will be considered unacceptable and they will do the old "jumping-up-and-down-test" through out the house. Trus Joist will provide performance crtiteria for their longer spans, because even if the strength and deflection is well within the code and table limits, the floor will vibrate. The TJI tables can be misinterpreted to allow an inexperieced engineer to specify a poor performing, but legal floor for average to very long spans. AISC has commentary that empirically limits vibration based on the depth to span ratio for steel members. Regards, Jeff Smith. S.E. phone: (415) 543-8651 fax: (415) 543-8679 email: smthengr(--nospam--at)sirius.com Smith Engineering 27 South Park San Francisco, CA 94107 --- Internet Message Header Follows --- Received: from server1.seaoc.org (bqe.com [22.214.171.124]) by host1.texramp.net (8.8.5/8.8.5) with SMTP id SAA02784 for <rlewis(--nospam--at)techteam.org>; Tue, 25 Feb 1997 18:11:30 -0600 (CST) Received: from mail1.sirius.com by server1.seaoc.org (NTList 3.02.10) id ba004525; Tue, 25 Feb 1997 15:54:57 -0800 Received: from [126.96.36.199] (ppp062-sf5.sirius.com [188.8.131.52]) by mail1.sirius.com (8.6.12/960710) with SMTP id PAA05949 for <seaoc(--nospam--at)seaoc.org>; Tue, 25 Feb 1997 15:49:23 -0800 Date: Tue, 25 Feb 1997 15:49:23 -0800 Message-Id: <199702252349.PAA05949(--nospam--at)mail1.sirius.com> To: seaoc(--nospam--at)seaoc.org From: smthengr(--nospam--at)sirius.com (Jeff Smith) X-Sender: seaoc-ad(--nospam--at)seaoc.org Subject: floor deflections, was: Re: building code minimums for wood frame Reply-To: seaoc(--nospam--at)seaoc.org Error-To: seaoc-ad(--nospam--at)seaoc.org X-Loop: seaoc(--nospam--at)seaoc.org X-Info: [SEAOC] Owner: seaoc-ad(--nospam--at)seaoc.org X-POP3-Rcpt: seaoc-ad(--nospam--at)seaoc.org Precedence: list X-ListMember: rlewis(--nospam--at)techteam.org [seaoc(--nospam--at)seaoc.org] __________________________________________________ Richard Lewis, P.E. Missionary TECH Team rlewis(--nospam--at)techteam.org The service mission like-minded Christian organizations may turn to for technical assistance and know-how.
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