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Re: Question for East Coast Engineers

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Dennis,

When I say that wind loads are not a problem, I don't mean that they are
neglected.  It's just that wind almost always controls over seismic for wood
framed structures in these parts, and that, unless you are in hurricane
country, there are no SPECIAL detailing considerations to undertake for wind
resistance.  For small structures (2 story residential, for instance) the
plywood sheating on exterior walls and a plywood diaphragm (all with 6"/12"
nailing) will usually suffice.  If necessitated by building geometry,
interior walls with gyp. bd. or plywood sheathing can be mobilized.  (Yes,
the SBC allows gyp. bd. shear walls).

Structures should always be analyzed for lateral loads, whether imparted by
wind, earthquake, or Godzilla.  It just so happens, that in many instances,
treatment of these forces by means of nominal framing will suffice.

Dan
--
Sherman D. (Dan) Vines, EIT
Heery International
-----Original Message-----
From: Dennis S. Wish <wish(--nospam--at)cwia.com>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Wednesday, May 06, 1998 4:04 PM
Subject: RE: Question for East Coast Engineers


Dan and Bruce imply that Wind loads are not a problem in smaller buildings
(for the most part) and that seismic loads are almost always lower than
wind. So my question still stands. What do you consider for the design of
lateral forces on smaller buildings (2 story or less).
I can't believe that any building is laterally stable when you apply even a
70 mph wind like we do in the West. There will be some lines of shear (or
more) that require lateral restraint.
Am I missing something? Are you analyzing the structures for lateral wind
loads and designing restraints or shear resisting elements?
Dennis

-----Original Message-----
From: Trobridge, Bruce [mailto:Bruce.Trobridge(--nospam--at)ogs.state.ny.us]
Sent: Wednesday, May 06, 1998 10:02 AM
To: 'SEAOC'
Subject: RE: Question for East Coast Engineers


I believe that the increase in 3 second gusts on the east coast is due
to hurricane force winds.  The Gulf of Mexico, Florida and the eastern
seaboard are subjected to hurricanes.  As you move inland the loads
decrease.  [ASCE 7-95 fig 6-1] I am not familiar with the west coast
but I would venture to guess that storms with winds of that magnitude
are less common.  Seismic accelerations, on the other hand appear to
be about ¼ of those on the California coast.  So I presume that it is
more likely that seismic loads would control over wind on the west
coast were the opposite is more likely on the east coast.

About 3 years ago a new building code was proposed for New York State
which contained seismic provisions.  The governor rejected it due to
the seismic provisions on the basis that it would increase
construction costs and would not be business friendly.  I suppose
bricks falling on your head is not business friendly either.  I will
say though that wind loads are not neglected.

Perhaps in the case of a pole barn on Martha's Vineyard the structure
is in an occupancy category and sized such that the designer did not
feel wind loads were an important factor.  Most of my work is with the
New York State Department of Corrections.  Due to security
considerations most of the buildings have solid grouted CMU walls with
bars in each core.  On low rise buildings that does not leave much
consideration for lateral design.

----------
From:  Dennis S. Wish[SMTP:wish(--nospam--at)cwia.com]
Sent:  Wednesday, May 06, 1998 10:38 AM
To:  Seaoc@Seaoc. Org
Subject:  Question for East Coast Engineers

Over the last few years, I have spoken to engineers and architects in
various area's out east who design wood structures and have little or
no
conception of lateral design and shearwalls. Granted, most of those I
ask
are from other professional newsgroups and not generally from the
SEAOC
list, but I am confused since the threads on wind loads indicates
design
loads in excess of most of those we find on the west coast (110-120
mph 3
second loads).
When I ask about this, they simply state that they don't have to worry
about
seismic in their part of the country.
One engineer designed post and beam structures in Martha's Vineyards
and
seemed unaware that the structure would be affected by lateral
motion.
What are the facts. Don't the engineers on the east coast consider
lateral
design for wind or are am I confusing area's were Brick buildings are
the
norm?
I'm curious since this would imply that there is a difference in
knowledge
related to load path and tying a structure together laterally.

Thanks,
Dennis

Dennis S. Wish PE
La Quinta, California
wish(--nospam--at)cwia.com

ICQ# 6110557
http://wwp.mirabilis.com/6110557
"The rich will do anything for the poor but get off their backs."
Karl Marx
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