|~|San Francisco Bay gets some big winds!
No argument there. (I remember the big winds in 96?. All sorts of damage
occurred outside Chico as well.) Belvedere has about 1.5km of bay between it
and sausalito, where the bay narrows. Maybe that could actually accelerate
wind. Personally, I don't think the engineer should solely have to determine
wind speed and exposure. The building official should base wind speed and
exposure on historical data and policy. The Belvedere official told me that
the back side of the Island could be C. He also reminded me of the 100mph+
winds at Angel Island
|~|We've seen 90 mph winds off of Angel Island. We've been out in
|~|the bay in
|~|about 55 mph winds with just a reefed mainsail and a 27,000 lb boat! Not
|~|to many years ago, a big tower went down from about 105 mph winds, if I
|~|remember correctly. I haven't designed anything at Belvedere,
|~|but we did
|~|do a number of townhouses in Pacifica where we used exposure D before it
|~|was required by the code. There were storys of the contractors trailer
|~|being blown over.
|~|But Exposure D is pretty well explained in Section 1616 and has
|~|a number of years, so I don't really understand why it comes up
|~|at this time.
|~|Neil Moore, S.E.
|~|neil moore and associates
|~|shingle springs, california
|~|At 04:09 PM 6/12/2001 -0700, Jeff Smith wrote:
|~|>I was told by the Belvedere, CA building official to use exposure D.
|~|>Belvedere is located well within the San Francisco Bay. It did
|~|not seem to
|~|>me to represent the highest wind exposure, however, it was
|~|about 100 yards
|~|>from the water on a steep hill. As it turned out seismic still governed.
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