To: "INTERNET:seaint(--nospam--at)seaint.org" <seaint(--nospam--at)seaint.org>
Subject: RE: ASD vs LRFD...my simple test
From: Mark Gilligan <MarkKGilligan(--nospam--at)compuserve.com>
Date: Thu, 3 Feb 2000 11:03:22 -0500
It is good to see that the steel industry has become more enlightened on
the issues of steel economy.
A number of years ago when LRFD was first being pushed there was a
traveling road show organized by AISC as I recall. The emphasis of this
presentation was on all of the special situations and tricks where LRFD
resulted in a savings in weight. To be honest this presentaion was a
turn-off. I felt like I was being sold a cheap used car.
Message text written by INTERNET:seaint(--nospam--at)seaint.org
> [I tried LRFD and ASD and] got the exact same member sizes...
Another respondent noted that LRFD was incorrectly promoted as a method
will save you material. It will in some cases, such as for gravity loading
when the ratio of live load to dead load is less than 3. Above 3, LRFD will
give you a heavier design.
I'm assuming your motivation to check into LRFD was maybe to see if you
could cut tons out of the structure. This is a mistake in my opinion,
because least weight is not synonymous with least cost. The details are
drives the cost. Labor, not tons!
I know that may surprise some of you to hear that, but I think my claim is
well substantiated in the following link (it's the same link I posted
yesterday, sorry for the repeat).
I think you'll note in that piece that the economy suggestions given
have nothing to do with which design method you are using.