Subject: Re: Rigid vs Flexible Diaphragms - Some Comments
From: Jim Kestner <jkestner(--nospam--at)somervilleinc.com>
Date: Fri, 07 May 1999 09:56:44 -0500
My approach to this problem is similar to yours, although the projects
that I have done in California are few and far between and the more
recent ones we have used local consultants. I typically calculate the
wall and diaphragm forces for 3 conditions: flexible (simple span),
semi-rigid (continuous beam) and rigid (distributing shears based upon
stiffness of the resisting elements and adding the torsional shear
component). I bound the problem by using the higher forces from each
analysis. With this approach, I don't need to agonize over whether the
diaphragm is flexible or rigid. It takes more time to do this, but the
answer covers all conditions.
This approach can be incorporated on large projects, where the fee is
bigger, but I can see the difficulty of doing this more complicated
analysis on small house projects where the fee is minimal.
Jim Kestner, P.E.
Green Bay, Wi.