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[SEAOC] Re: [SEAOC] Re: [SEAOC] Plywood Shearwall Deflection[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaoc(--nospam--at)power.net>, <seaoc(--nospam--at)power.net>
- Subject: [SEAOC] Re: [SEAOC] Re: [SEAOC] Plywood Shearwall Deflection
- From: "Dennis S. Wish PE" <wish(--nospam--at)cyberg8t.com>
- Date: Wed, 3 Jul 1996 16:55:46 -0700
- Cc: <seaoc(--nospam--at)power.net>
I, too, have used the UBC Standard's design criteria for plywood shearwall deflection and have found that the story drift on narrow panels exceeds the allowable story deflection by as much as 300 percent. My question, though, is if there is a design criteria for a shear panel that spans across an opening. In other words, how do you determine the story drift on a ten foot wide shearwall that has a 4 foot x 7 foot high opening in the middle of it? This makes the assumption that the area above the opening is part of the panel (also assuming that it is adequately straped both top and bottom to the adjacent panels). How do you determine the deflection of the combined system without isolating the individual panels. Tom's recommendation is valid and is the customary method of using the panel above the opening to reduce the effective hight of the shear pier and thus the H/b ratio of the panel under consideration. In this example, the panel is still too narrow to comply. The only reasonable solution (other than provideing a stiffer element such as a frame) is to combing the piers and analyze the entire system for deflection. This leads to another question. Will the City of Los Angeles (or any other building department that complies with the same design criteria) allow the use of a narrower panel width if the engineer designs the panel for story drift in accordance with the UBC Standard? If they allow the design and a problem occurs in the future, is the engineer liable for "errors" based upon his design assumption and the acceptance of the city? Your input is greatly appreciated on this issue. Dennis Wish PE ...
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