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Re: ASD steel composite beam design

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You really need to look at the 13th Edition for ASD composite design. I do like the color highlights.

The big argument and material advantage for going to LRFD back in 1986 when the LRFD first Edition hit the streets, was to reduce beam sizes and stud quantities. The issue was more in that there was research that manifested itself in the LRFD, but the ASD was never updated by the research that fed into the '86 LRFD. Prior to 2006 and the 13th Edition, the ASD composite design was predicated on composite research and design practices developed in the 1970's.

Beams and concrete did not know or care if you were designing in ASD or LRFD so the results should not have been as divergent as they were. With the current 13th edition ASD, the resulting members are not as divergent (ASD vs LRFD) although I have not done any formal study and analysis comparison.

The only thing that I know for sure is that the research and design methodology in ASD composite beam design took a 30 year leap with the 13th edition.

If I am way out of line, I am sure that Charlie Carter or other AISC smarter than me guys can correct me.

.... I remember when the 7th edition was baby blue and new. It came out in 1970. The year I graduated from high school. ...bell bottoms and the draft was something more than a cool breeze.

Regards,
Harold Sprague


From: David.Topete(--nospam--at)wildman-morris.com
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Re: ASD steel composite beam design
Date: Fri, 15 Sep 2006 08:31:03 -0700

No, it doesn't.  The non-composite section is at full allowable bending
capacity, and is defelecting about 2" under total load.  I would think
that if Iuse the 1/4 Vh value, I greatly reduce the number of weld
studsdeflections are still within allowable limits.  Just reading through
the ASD spec, it almost seems as if it's all or nothing if the reduced
horiz shear Vh' doesn't calc to at least 1/4 Vh.  Actually, reading the
paragraph on 5-59 as you've pointed out kinda answers my question.  Thanks
Will.

David A. Topete, S.E.



"Will Haynes" <gtg740p(--nospam--at)gmail.com>
09/14/2006 05:42 PM
Please respond to
<seaint(--nospam--at)seaint.org>


To
seaint(--nospam--at)seaint.org
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Subject
Re: ASD steel composite beam design






By page 5-59 it looks like you do have to meet the 1/4 minimum if using
any composite action. Does the beam work without studs at all? I have used
non-composite beams on a floor where the rest of the beams were composite.



Will H.


On 9/14/06, David.Topete(--nospam--at)wildman-morris.com <
David.Topete(--nospam--at)wildman-morris.com > wrote:

Following the examples for composite beam design in the ASD 9th edition,
when economizing by taking advantage of partial composite action, does Vh'
have to be at minimum 1/4 x Vh?  I ask because for a fully composite beam,
I would need a total of 70 weld studs.  But, when computing for partial
composite beam action, to economize on the weld studs, the calculated Vh'
is a hair above 0kips.  Intuitively, I would guess that the intent of the
1/4 Vh is to have some horiz shear force to design for, although it is not
explicitly stated in the spec or commentary...
TIA for any clarification provided.

David A. Topete, S.E.


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