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Re: single angle compression members

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Good Morning Ken -
 
I think that a distinction is made between single-angle connections and single-angle members.  The procedure on pg 3-55 covers the design of a compression strut (aka column) as opposed to the materials used in a connection which is what the Spec Section J.1.9 is addressing.  For a further discussion of eccentricity & connections, see pg 10-134 of the new LRFD Manual, and pg 3-13 of the older Vol II - Connections Manual.
 
HTH
 
Scott A. Dunham, PE
Dunham Engineering Services
Dothan, AL
334-678-6948
 
----- Original Message -----
To: Seaint
Sent: Tuesday, September 24, 2002 5:28 AM
Subject: single angle compression members

I realize that I am looking at an outdated publication, but will ask your opinions anyway: AISC 9th edition J 1.9  indicates that the eccentricity of single angles connected by welding or bolting can be ignored for statically loaded" members, but page 3-55 gives a nice example showing that when the eccentricity is not ignored for the member design, the allowable axial compression load is greatly reduced (for the example the allowable load is only about 1/3 of the allowable load found when ignoring the eccentricity - there is a nice article written by Wayne Walker on this in the AISC Engineering Journal Second Quarter 1991 which has allowable load tables for single angles if any of you are interested).  Am I correct in my interpretation that the eccentricity can be ignored for the connection design only or was J1.9 was just "older" thinking as far as single angles goes and 3-55 was representing the results of newer research? (I see a reference to 1988 work on page 3-55 and 1942 work is referenced in the commentary for J1.9.)  Should the eccentricity of the connection be included in the connection design?
 
Thanks in advance.
 
Ken

Kenneth S. Peoples, P. E.
Lehigh Valley Technical Associates
1584 Weaversville Road
Northampton, PA 18067-9039
Phone: (610) 262-6345
Fax: (610) 262-8188
e-mail: kpeoples(--nospam--at)lvta.net