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Re: Seismic Zones in Texas

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What a wonderful analysis!  Thank you for the insight and validation.  I have
often worried about the "computer" solution and the lack of lessons being passed
on.  I thank my lucky stars that I had mentors like Don Kay and Henry Sanders to
help me through the learning curve and teach me what they had learned.
Thankfully I was receptive to what they had to tell me and actually learned from
it.  I can only hope that the next generation learns from our mistakes and
carries that on as well.

Roger, you have a wonderful way with words.  Thank you again.

Roger Turk wrote:

> No, Ken, you are not getting old and afraid of change.  You are getting wiser
> in your older age.
> What is happening is what Henry Petroski describes as the 30 year (or 35
> year) syndrome.  Since 30 to 35 years is the approximate working life of an
> individual, what he/she has learned *not* to do in that time, and the reasons
> for it, has not been adequately passed down to the younger members of the
> profession, they *don't* know what experience has shown to be inadequate.
> Therefore, we start having a series of failures every 30 - 35 years.
> Compound this with educators that have had little or no practical experience
> who rely on computers that spit out answers in accordance with the
> instructions that *they* put into the computer and we are in for some *big*
> problems.
> In the early 1960's it was a real chore to get masons to put reinforcing in
> masonry, at least here in Arizona.  ("All we need is a header every 5 courses
> and the wall is not going to go anywhere.")  Finally we were able to get
> masons to accept the need for reinforcing, however, the new masonry codes
> erode this requirement for seismic zone 2 locations by extrapolating tests
> that were intended only for small, single story, lightly loaded masonry
> construction to all masonry construction in seismic zone 2.
> The USGS Seismic maps are not gospel.  Depending on how the head of the USGS
> seismic branch wants to have the maps look will depend on what we see.
> Algermissen's first map (1971), based on historical seismicity, was quite a
> bit different than his second map (ca. 1985), based strictly on probability
> (and politically modified), which is quite a bit different than Arthur
> Frankel's map (ca.1990's), which is based on a combination of probability and
> historical seismicity, which is quite a bit different from his map that
> doesn't have the accelerations divided by 4.  Have you seen the USGS map that
> shows California accelerations of 3.9g?  I would venture to say that very few
> people have.
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona
> Ken Tarlow wrote:
> . > Is anyone else thinking this will be a disaster? or am I just getting
> . > old and am afraid of change.