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# RE: X-Bracing

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: X-Bracing
• From: ESuk(--nospam--at)technip-coflexip.Com
• Date: Tue, 11 Feb 2003 10:00:47 -0800

```If I remember the theory behind that properly, that assumes that one of the
braces will be in compression while the other is in tension (the braces
prevent sidesway).  Which means that you can use the effective length for
both in and out of plane as half, IF you trust that the tension in one will
resist the buckling tendency from compression of the other brace.  Further
research (again, if memory serves) says that the lateral load to restrain
compressive buckling is around 5% of the buckling load of the compression
member.  So, in theory, it's ok to assume that the tension member can
restrain the other member from buckling out of plane.  Personally, I feel
the reduction isn't worth the risk or the time.  Most of the bracing I deal
with are fairly insignificant relative to the rest of the structure.

|---------+--------------------------->
|         |           "Greg Meyer"    |
|         |           <gmeyer@scahoust|
|         |           on.com>         |
|         |                           |
|         |           02/11/2003 09:13|
|         |           AM              |
|         |           to seaint       |
|         |                           |
|---------+--------------------------->
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|        To:      <seaint(--nospam--at)seaint.org>                                                                            |
|        cc:                                                                                                     |
|        Subject: RE: X-Bracing                                                                                  |
>----------------------------------------------------------------------------------------------------------------|

Per the publication "Seismic Design of Steel Structures" p.222
"The distance between lateral supports, for each brace, may be assumed
to be half the full theoretical length of the brace, for both in-plane
and out-of-plane effects"

HTH

Greg Meyer

-----Original Message-----
From: RainCat1(--nospam--at)aol.com [mailto:RainCat1(--nospam--at)aol.com]
Sent: Tuesday, February 11, 2003 10:42 AM
To: seaint(--nospam--at)seaint.org
Subject: X-Bracing

What do you use as the effective length? Is it half the brace length for
both Ly & Lx or full length for one axis and half on the other axis?
I know there were studies that you could use half the length of the brace -
could anyone point to the latest word on this topic?
Thanks a lot!

Rainier C. Catubig
San Diego, California

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