To: "INTERNET:seaint(--nospam--at)seaint.org" <seaint(--nospam--at)seaint.org>
Subject: effective length factor for sway moment
From: Peter Higgins <76573.2107(--nospam--at)compuserve.com>
Date: Tue, 3 Apr 2001 10:18:09 -0500
Message text written by INTERNET:seaint(--nospam--at)seaint.org
>For frames NOT restrained against sidesway (drift), regardless of whether
not you have fully or partially restrained joints, K will always be > 1 and
can be much greater than 2, 3, or even 4.
(Simple sketches will show that this is true.)<
Not to nit pick too much, but there are cases of columns in a "sway
permitted" frame which will have a K<1. Yura in his seminars demonstrated
some. You might also dive into "Effective Length and Notional Load
Approaches for Assessing Frame Stability" by the ASCE Structural Institute.
Once again, as others have mentioned, K factors (not just their nomograms)
were introduced in the "pre computer" days. We really have much better
tools now, and should use them.
And I also used a slide rule which now sits in my desk awaiting a battery
failure in my calculator. However, I have retired my K factor nomogram
completely. I don't even use it for preliminary checking anymore.
Peter Higgins, SE