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RE: 1920's 9 story concrete frame building

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Well, the client showed up with some plans and to my surprise the first 5-6
floors have square columns with #3 spiral ties at 1.5 to 3" pitch. The
vertical reinforcing ranges from 6 3/4" dia. to  10-7/8" dia bars. Above the
sixth floor there are basically 4 bars with # 2 ties at 10" o.c. Concrete
was a 1-2-4 mix for the heavy columns (what does that mean again?)I left the
plans at my office so the details are a bit sketchy. Bob, I am sure you and
other SEAONC members would recognize the original Engineers, another
colleague did. Werner (maybe) someone, someone and Russell I believe. Their
offices were on Pacific. Even though I am amazed with the amount of
reinforcing, I still would be very nervous in that building,it is very heavy
with the pan joists. The aspect ratio is closer to 2.5:1 and it is sort of
"z" shaped in plan. I have a client who is equally concerned about seismic
safety and the view, meanwhile a frenzy is building and other bidders are
lining up without any consultant review what so ever. Maybe my client found
out about the sale too late or maybe the sellers are note allowing enough
time for buyers review, I am not sure.
Regards,

Jeff Smith

|-----Original Message-----
|From: Robert J Bossi, PE [mailto:rjbossi(--nospam--at)sonic.net]
|Sent: Tuesday, May 11, 1999 5:54 PM
|To: seaint(--nospam--at)seaint.org
|Subject: Re: 1920's 9 story concrete frame building
|
|
|Jeff:
|I agree, particularly if the non-ductile concrete frames are in the short
|direction.  This building probably also has a height to width
|ratio of 3-4. Even
|if you had plans, you probably won't find the column steel tied
|with anything
|more than #2 (two) smooth ties at 12" oc.
|
|Jeff Smith wrote:
|
|> A past client of mine is putting in a bid for a condo flat in Pacific
|> Heights S.F. Million dollar views, very exclusive. It has a
|concrete frame
|> in the short direction and property line infill walls in the
|long direction.
|> It could be on bedrock. The floors are concrete pan joists. The
|building is
|> 9 stories with single units per floor. My initial reaction without any
|> analysis is....not a good idea. Is there any possibility that a building
|> like this could have any margin of safety during a near fault 7.0
|> earthquake? Building plan records are available, but not until
|after the bid
|> date is due. My only comment will be that this building is not
|expected to
|> do well during a credible seismic event.
|>
|> Regards,
|>
|> Jeff Smith
|>
|
|
|