Subject: Re: Adding a mezzanine to a Masonry Building in Seismic Zone 4
From: David B Merrick <mrkgp(--nospam--at)pacbell.net>
Date: Thu, 17 May 2001 10:52:51 -0700
I just inspected the footing excavations in San Francisco for a new mezz
that in addition, pushed up the roof about 4 feet.
To keep from adding load to the opposite wall I added a steel braced
frame at the interior edge of the mezz. The roof offset, lines up with
the mezz edge and new braced frame. The omega factor made the connection
demands nearly impossible to meet.
The conc block wall had a little steel but I averaged the pilaster
reinforcement with the wall to find enough for the existing walls to
meet the minimum. The walls are capped with 12x12 concrete beams, the
block continues up past the bow string truss profile to create a
parapet. Anchoring into the wall included filling cells with in a 8"
radius of the bolting.
Demolition exposed a diagonal Loma Prieta crack. We filled in the cells
near that too. For that one area, between pilasters, I told the owner
that it would be best if we just rebuilt the wall segment. But to keep
the machine shop working 24 hours a day he wanted the wall to remain and
have the cells filled. The previous retrofit, since Loma Prieta included
pressure grouting the soils.
I took advantage of the San Francisco 0.75 EQ factor for existing bldgs,
and increased the EQ demand where there was not a cost savings for
construction. A previous upgrade of roof plywood by an engineering group
had over looked the narrow strips of roof between the walls and long
skylights. The strips of plywood roof were long and narrow acting as
beams with not enough shear capacity to resist the out of plane wall
loads. I added plywood and straps to the under side.
I bought a small Stanley survey Transit from the late 1800's. I found it
at a sidewalk flea market in Berlin Germany. My dad is a retired
surveyor and once acted as a navigator for a 1967 Antarctic exploration.
Most maps now show the "Merrick Mountains". Dad is proud of his survey
days. I had the shop, using this building, machine a brass adapter to
fit a tripod top to the weird threads of the transit. Dad's birthday is
coming soon. Since then I found that a company "Stanley London" is
making replicas of the transit. I can't find anyone with an original.
theirs is mark "Stanley London". Mine is Marked "Stanley".
* This email was sent to you via Structural Engineers
* Association of Southern California (SEAOSC) server. To
* subscribe (no fee) or UnSubscribe, please go to:
* Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
* send to the list is public domain and may be re-posted
* without your permission. Make sure you visit our web
* site at: http://www.seaint.org