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RE: Shear Wall Design[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Shear Wall Design
- From: "SEConsultant" <seconsultant(--nospam--at)earthlink.net>
- Date: Tue, 16 Nov 1999 16:36:26 -0800
Mark, Actually, reviewing my comments, I pulled the figures for wind from an old program I wrote. What I forgot to take into consideration is that I increased the OT moment on the wall by 1.5 if wind governed - which is the reciprocal of 0.666667. I realized this only after I sent the letter. Thanks for bringing this up - it deserves correction. Dennis -----Original Message----- From: Swingle, Mark [mailto:Mark.Swingle(--nospam--at)dgs.ca.gov] Sent: Tuesday, November 16, 1999 2:59 PM To: 'seaint(--nospam--at)seaint.org' Cc: 'mswingle(--nospam--at)earthlink.net' Subject: Re: Shear Wall Design Dennis, A minor correction. Re: wind: In the 94 UBC and the 97 UBC, the effective allowable dead load ratio to use for resisting overturning is 2/3 for wind. See 94 UBC 1619.1, 2nd paragraph, and 97 UBC 1621.1, 2nd paragraph. It is not 100%, but 67%. Re: seismic: In the 94 UBC, the effective allowable dead load ratio to use for resisting overturning is 0.85 for earthquake, as you said. See 94 UBC 1631.1, 3rd paragraph. In the 97 UBC, the second sentence of the corresponding paragraph is removed from 97 UBC 1633.1, 3rd paragraph. So the 85% no longer applies in the 97 UBC. Inquiring minds want to know.... what's an engineer to do? Well, now you get to use a load combination that had no equivalent in the 94 UBC, namely 12-6 OR 12-10 OR 12-16-1 OR 12-18, depending upon your situation (don't ask!). And the winner is, 90%!!!! (Of course, this previously existed in some of the material chapters.) This is the first item I have noticed that is more liberal than the previous code. Rejoice! Mark Swingle, SE Oakland, CA -------------------------------- Dennis Wish wrote: Therefore, you are permitted to consider 85% of the dead load on the wall (for seismic) and 100% when wind governs to resist uplift on the wall (this may have changed in the 97 UBC but I have not looked lately).
- Re: Shear Wall Design
- From: Swingle, Mark
- Re: Shear Wall Design
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