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RE: ICBO Seminar for 1997 UBC Earthquake Regulations

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Thor, are any of the test results published? I would be very interested to
see what his conclusions were. I am not against conforming strictly to code,
but it seems that there still are differences of opinions as to what R value
to use for the entire structure when using a pendulum lateral support in one
line of shear. Personally, the idea of using an R=2.2 destroys the use of a
"flag pole" for lateral restraint on any structure because of the cost of
compliance of the whole structure.
If the top of the flagpole is bolted to a header and buried in a stud wall
with blocking, are we really getting full translation and rotation freedom
or should this be modified to be more realistic with the restraint at the
I'd like more information on how others feel about this and any conclusive
testing to prove it to be a rational option.
Thanks for your information. If you have the data from BC, let me know how I
can get a copy. I would be very interested in reading it.

-----Original Message-----
From: T [mailto:vicpeng(--nospam--at)]
Sent: Wednesday, April 22, 1998 3:10 PM
To: seaoc(--nospam--at)
Subject: Re: ICBO Seminar for 1997 UBC Earthquake Regulations


My response was to the discussion on what R factor to use for different
element configurations and mixtures thereof.  Some postings were advocating
flexible diaphragm assumptions, others using stiff diaphragm etc or some
hybrid assumption.  I had just attended a seismic design seminar where John
Pao P.Eng of Bogdonov Pao & Assoc of Vancouver  BC presented the results of
analyses (single story box-type structures) he carried out taking into
account the diaphragm stiffness and associated boundary conditions.  He
found that a number of structure type-mixtures resulted in wall loads
differing significantly from loads calculated by the simplistic tributary
area or stiff diaphragm assumptions ie "engineering judgement".

Thor Tandy

>Thor, I think you pointed out (if we are on the same track) the same proof
>of diaphragm deflection that was visible in relatively stiff (500

> the same line of shear.
>If you don't agree with me, please explain.
>Dennis Wish PE

>.......This an example of how we neglect the boundary effects of
diaphragms.  At a
>recent seminar it was demonstrated that depending on all aspects.....
>.....judgement" will check if the computer data is sensible or not.
>Thor Tandy
>Victoria BC
>>Regarding the use of Rw=3 on one wall line only where the cantilever
>>occurs, I'll be carefull about this. We have to use our judgement.
>>Just my opinion.
>>Ernie Natividad