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Re: Completly shearing a building (also answer to perforatedshearwalls) -Reply

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Thank you and thanks to the others who responded with the same eloquently 
stated opinions. My comments were, at most, cynical to the current design 
methodology. How the heck are we going to change the course that Seismology 
Committee is taking which affects our practices yet has little if any 
calculable effect on the performance of residential structures.
In my example, the contractor may be doing a service by increasing the 
stiffness of the overall structure, but he is also ruining the calculated 
distribution of force by stiffness which may, theoretically, alter the 
performance of the building. Do I believe it to be a negative effect - no 
way. However, the liability that is transfered due to over-specification of 
the methods is unwarranted in residential design which experiences field 
changes as a normal part of bulding a home. I don't believe that the same is 
true of commercial and industrial stuctures which are built to much more 
ecconomical standards and do not generally experience major changes in the 

As I mentioned to others - how do we change the course that Seismology is 
taking by trying to tie up all methodologies into one neat design so as to 
comply with what is believed to be the answer to Vision 2000. They really did 
not listen at the August 14th meeting which was meant to apease the community 
to a small degree but planned to proceed into publication of the blue book 
provisions already drafted by Kelly Cobeen prior to the opinions expressed by 
those in attendance?

Dennis Wish PE

In a message dated 9/14/1999 10:01:45 AM Pacific Daylight Time, 
david_puskas(--nospam--at) writes:

<< ** High Priority **
 When it comes to single family residences it seems to me that we disregard 
the contribution of the plaster, stucco, drywall, drywall tape, ring shank 
nails, dry wall nails, paint, wall paper, shelving attached to the wall, 
electrical and plumbing conduit, etc, etc, etc, where they occur, when 
determining the stiffness of the structure to resist lateral loads.  It seems 
the way things are going we will have to build a full scale model to 
accurately determine which loads go where.  Not to metion the numerous 
deviations or conditions which normally occur during construction such as 
notched studs, relocated interior non-bearing walls, termite eaten framing 
members.  In my opinion the more we try to quantify everything the more we 
are tying our own hands (and fees).  How accurate do we really need to be 
when designing a building to protect the life and safety of the general 
public?  Are we to do an anlaysis everytime a minor element in the structure 
is changed, or take weekly site visits to input the contractors 
interpretation into our analysis everytime it deviates from our design 
assumptions?  What is he answer?
 Dave Puskas
 BSW International - Tulsa >>