From: Davis Parsons <dparsons(--nospam--at)msc-engineers.com>
Date: Thu, 24 May 2001 18:18:26 -0500
In non-seismic, 90-100 mph wind areas you can use eccentric tension
braces to miss windows or door openings. If you can't line the braces up
vertically, you could place one brace on one floor and place another in
line with it on the next floor down. Then you could use floor beams to
"drag" the load from one brace to the other.
On exterior walls, we use flat plates installed just inside the metal
studs for bracing. If we use gage metal for the brace, then the interior
gyp. board can be mounted directly to the studs. If we use plate up to
1/4", then the architects we work with will add a 5/8" hat channels to
the inside of the stud to allow the gyp. board to miss the braces.
Knee-braces will work provided you have the plenum space to use them.
If there is absolutely no location for bracing, then you have to
consider either moment frames or cantilevered columns. How about 46'
cantilever columns? Those were W14x283 because the architect did not
allow any location for a frame. With moment frames, we have found that
if there are no architectural restraints, traditional beam sections work
better. I have a 45' 2-story building with interior moment frames using
W27x84 as columns
As for bad-mouthing architects, I have found that most architects in
non-seismic locations have never had any training about lateral forces.
They do not understand the extent that the steel cost is affected by
their designs. Once they understand that the cost of the structure will
decrease, most architects will try to give wall locations for bracing.
Davis G. Parsons II, PE RA AEI
a practical structural engineer
Fort Worth, Texas
* 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