Return to index: [Subject] [Thread] [Date] [Author]

Re: "X" Bracing

[Subject Prev][Subject Next][Thread Prev][Thread Next] Ben,

Don't forget about the exception in section 2213.8.2.3 regarding a single
diagonal brace to take the entire force in "compression only" when you design
including omega and neglect the beta value.  I agree that this section
eliminates tension rod braces since they have no compression capacity, but
wide flanges and tubes do have compression capacity and can be used in
compression taking 100% of the design force when designed in accordance with
this exception.  The omega factor would be applicable if you had only single
diagonal braces per bay all in the same direction in the same frame line (all
braces take either compression or take tension depending upon direction of
lateral force).  If the single diagonal braces per bay are in opposite
directions (some tension, some compression) in the same frame line, then it
may be possible to omit the omega factor in checking the single diagonal
braces depending upon force distribution and the 70% check.

Michael Cochran S.E.

In a message dated 5/24/2001 1:39:00 PM Pacific Daylight Time,
Ben.Yousefi(--nospam--at) writes:

   The section that prohibits its use is 2213.8.2.3, although not
explicitly. It basically prohibits the use of braces that would be all in
tension or compression along any line of resistance. For tension rods, 100%
of bracing is in tension, therefore it does not meet the intent of this
section. This could also apply to other types of braces, such as WF, tubes,
etc. If they are situated in way that all would be in tension or compression
at the same time, they would not meet this section's requirement.

   Ben Yousefi, SE
   San Jose, CA