Subject: Re: Seismic Upgrade.... Blue Book Commentary on wood diaphragm
Date: Sun, 23 May 1999 18:25:46 EDT
I couldn't agree with you more. I just need to add a point of clarification
and an additional comment here:
1- Your statement that the use of rotation was disallowed by the code
for multistory buildings may be more of a wishful thinking. The language in
the code for allowing rotation unfortunately has not changed for some time.
If you refer to the 7th paragraph of section 2315.1 in the 97 UBC the concept
is still allowed if you meet some dimensional and aspect ratio requirements.
The only reason you don't see more of these building being built, is that
most designers have the common sense of not opting for a scheme that has
proven to be problematic. Maybe this should be the focus of a future change
in the IBC which continues to allow this practice.
2- This whole argument for verifying wood diaphragm rigidity will possibly
legitimize the concept of open front design even more, as more designers may
opt to use it after they discover their diaphragms are rigid once they
perform diaphragm deflection calculations using those exact equations that
includes such scientific functions as nail slip!