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RE: Light Column Tables in MSC 13th Ed

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I meant to respond yesterday, but forgot until I saw this reply. Sorry.

 

There is no prohibition for the use of W6, W5, and W4 columns, and one can calculate a strength for them easily with the specification equations. But the Committee responsible for the Manual left them out of the tabulated information on purpose to encourage thinking about it before you do. It is very difficult to make connections to small W-shape columns work. Any economy gained by weight savings is quickly lost on connections in the majority of cases.

 

In the 3rd Edition LRFD Manual, we left out W8s too for the same reason. This same question back then led to a reprieve on W8s this time around.

 

Charlie

 


From: Szuchuan Chang [mailto:szuchuan(--nospam--at)gmail.com]
Sent: Friday, August 04, 2006 1:08 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Light Column Tables in MSC 13th Ed

 

Jordan,

 

I had the same question just like yours.

 

In the LRFD 3rd edition, the column table ended at W10x33. No W8 columns listed at all!  Now that OSHA requires 4-bolt connections at the baseplate, you have a very large base plate to work with.

 

The 13th ed lists the HHS as compression member to HSS2x2.  A HSS3.5x3.5x0.25 is good for 16 kips at 18' feet (ASD).  It weights about 10.5 plf.  Say the material price double over a W8, it is still cheaper than a W8x31. 


My problems are in review of old existing buildings, I had to prepare my own calculations because the Fy=36 ksi not the same and the smaller shapes are not listed in the tables.

 

HTH

 

Sam


 

On 8/3/06, Jordan Truesdell, PE <seaint1(--nospam--at)truesdellengineering.com> wrote:

I was just looking up some prelim column sizes in the 13ed of the AISC
MSC and they have truncated the W tables at W8x31.  I could have sworn
there were smaller sizes, so I looked at the LRFD 2nd, and they go to
W8x24 and also list W6, 5, and 4s.  Have these shapes been largely
supplanted by HSS sections and therefore deemed not worthy of book
space?  Last I heard, HSS (mat'l only, FOB local distributors) was
almost double the cost of W shapes.

Any insight as to the oversight?

--
Jordan


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