We learned how do perform lateral drift calculations in the '50's using moment distribution and other classical methods. Our text book was "Analysis of Statically Indeterminate Structures" by Williams. (which I still have on my bookshelf today). We had learned the graphical methods in our stress analysis class in our junior year. I have both the Klienlogel books, "Beam Formulas" and "Rigid Frame Formulas". (Picked up in London) Believe I "programmed" some of the frames in Visicalc.
Our class (of about 22) all used slide rules - mine was a larger circular.
Neil Moore, PE, SE
still with a passion for engineering like Harold and the rest of you.
On 11/1/2011 8:50 AM, Harold Sprague wrote:
Back in the 1970's, I was trained by engineers who did not know computers. They used graphical methods and other approximate methods to calculate lateral drift. I came in on my white horse and was going to teach the old hands how to calculate lateral drift the computer way. They could do it faster by a long shot, and we were well within about 5% of my "modern" ways. ...I was not worthy.
I have collected many approximate methods in order to calculate lateral drift quickly with only a calculator (or even a slide rule).
These are some additional very good tools:
Kleinlogel had a book of formulas for frames in the 1950's
Hool & Kinne wrote " Stresses in Framed Structures"
AISC "Single Span Rigid Frames in Steel" in 1948
AISC published a really neat little one page frame drift tool in Modern Steel Construction, Steel Interchange in April 1993. It was based on Kleinlogel.
I have used a similar method that you list below. I think you will be surprised how accurate the approximate methods are.
Regards, Harold Sprague
Subject: Standard Portal Frame Analysis
Date: Mon, 31 Oct 2011 11:28:31 -0700
I'm doing stuff I should done in school J
1) I am reviewing how to quickly arrive at sway in a rectangular (or any, for that matter) portal using simple portal frame equations.
2) I calculate the moments from the std equations and then release the top corners to arrive at a flagpole concept tied at tops by a strut/beam.
3) The resulting base moments are approx by iterative moment distribution.
4) If I use a partial, or offset, load on the beam I expect sway.
5) My question is, "Is it too simplistic to take the resulting moment difference at the bases and apply slope-deflection arithmetic to arrive at an estimate of the sway?"
Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE
Victoria, BC, V8T 1Z1