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Re: Large Bay 'X' Bracing

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I see that my earlier response has not found its way to the list, yet.

In that I stated that the limit on L/r is not mandatory anymore (AISC 13th Ed) and that any section fulfilling force requirement would be adequate. For example, C6X8.2. However, I overlooked the effect of the member's self weight. C6X8.2 may deflect more than 1.25" under its own weight. W14X26, on the other hand, deflects less than 3/8".

Anyway, if you forget about L/r<300 requirement you may have multiple choices. Just remember the deflection under self weight. If the sag is too much(what is too much?), it may be too late before the brace comes in to play.

Rajendran


Rich Lewis <seaint04(--nospam--at)lewisengineering.com> wrote:
I have a warehouse condition of a ?X? braced bay that is 31 feet high and 42 feet wide.  The diagonal length is over 51 feet.   I?m wondering if I should try to use the bracing as one large bay, or add a wind column in the middle and have two smaller bays.  The bracing is tension only for wind loads.  The load in the diagonal is about 21 kips.  What makes me most uneasy is the slenderness ratio of the brace.  If I try to limit the L/r ratio of the out of plane axis to 300 then I get extremely large angles.  If I ad a column I add almost 50% more bracing length, plus column and footing.
 
Thanks for your insight.
 
Rich
 


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