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Re: WT Bracing for OCBRs

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have you gotten an answer?  I agree with you that it would be the 4th item of table I-8-1.  I also agree that the WT 6x95 being incredibly conservative based on the expected demand...

On Tue, Dec 14, 2010 at 3:21 PM, <Tom.Hunt(--nospam--at)fluor.com> wrote:
I have a non-building steel piperack (similar to buildings) in SDC D where we are using an Ordinary Concentrically Braced Frame System (R = 3.25) with WT double story cross bracing.  For this, ASCE Table 15.4-1 requires AISC 341 detailing that gets you to Section 14.2 which says the braces must meet the requirements of Section 8.2b (i.e. the braces must be seismically compact) per TABLE I-8-1.

Now for the question.  Which item(s) in TABLE I-8-1 applies to WT flanges and stems in an OCBF system?  The way I read the table, it would be the fourth item down per the last part that says "....and braces [c]...." where footnote [c] second part is for "...braces in OCBF, Section 14."

Others read the table as the last item that specifically addresses stems of tees but footnote [g] only applies to STMF systems.

The reason for the questions is that with my first interpretation, the smallest WT that has a bf/2tf AND h/tw less than 7.22 (i.e. 0.30 x sqrt[E./Fy]) is a WT6 x 95 which would be rather ridiculous for a small structure.

Thanks,

Thomas Hunt, S.E.
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