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wood diaphragm revolt.

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Dear Who ever is listening,

Anyone who as designed 2,3 or 4 story wood frame structures in the City Of
Los Angeles lately must be frustrated.  The fear of performing a rigid
diaphragm analysis looms over every project.  The people who decide whether
the analysis is warranted will undoubtly be a plancheck Engineer with about
10 minutes of experience.  Lucky for us he/she has the 10 minutes of
experience otherwise they would require us consider the weight of the
foundation below grade in our building mass  (don't laugh I can give you

Wishing that the members of the seismology committee who brought these rigid
diaphragm changes to us be hung by their xxxxxx no longer works, and
something must be done.  In my frustration I called an old good friend who
is very involved in the SEAOC and asked his advice.  Here is a plan.  What
if we were to gather, say 20 or more projects designed by engineers in
California, Nevada or Washington, where rigid diaphragm analysis was
required, and analyze their results.  We might be able to answer the
question 'Did the added work provide us better information?' (I am sure the
seismology committee never asked this question.)

These buildings would be up to 4 stories, wood frame, blocked or unlocked
diaphragms, and mostly residential structures.  Perhaps we can show that
rigid diaphragm analysis provides us with no useful information and doesn't
change the design.  Perhaps in the cases where the design actually does
change, a new set of criteria can be evolved to help us spot diaphragms that
may need the extra analysis, or better yet can help us derive more simple
design procedures for these diaphragms.

Anyone who would like to please  E-mail me.  Anyone who has a building they
would like us to consider that may be suitable for our analysis please
E-mail me.  Perhaps we can get enough projects together and right a first
class paper and submit it to the Seismology Committee and the City of Los
Angeles.  Perhaps we can stop this nonsense.


Ken Tarlow
Tarlow Engineering
Fax 562/436-6875