Subject: Re: HSS vs. TS Properties For Design (WAS: Re: Copyright Infringement)
From: Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
Date: Thu, 11 Jan 2001 14:43:41 -0500 (EST)
You are correct (at least as I understand it). The "new" section
properties ARE based upon the lower bound. The reason for the change is
that the tube producers, in the not so distant past, became able to
produce at that lower bound with very little variation. Therefore, tubes
that are produced today typically have section properties that are less
conservative than the values in the ASD _AND_ LRFD manuals. Thus, the
"new" (more realistic) section property values in the HSS manual. If
memory serves me correct, there is aabout a 7% difference in actual wall
thickness between the new and old values.
My main point was that the "new" values are not LRFD values. But,
definitely keep up the good fight for LRFD (but don't forget to duck and
cover every once and awhile to avoid the wrath of the old ASD guard...I am
still kind of in that camp <grin>).
On Thu, 11 Jan 2001, Bill Polhemus wrote:
> Scott Maxwell wrote:
> > The difference is today
> > the tube producers are much better able to produce the tube thickness to
> > the allowed minimum thickness in the ASTM spec.
> I had a little different take on it. I took it to be that the "new" section
> properties represented the "lower bound" of the material thickness under the
> tolerances in the ASTM spec, period.