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Re: Architect cheating on structural calculations - where's the building depa...

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In a message dated 12/9/2005 1:19:59 PM Pacific Standard Time, Gautam_Manandhar(--nospam--at)ci.richmond.ca.us writes:

I understand your fraustration about the rigid/flexible diaphragm because that
goes against the general practice.  However, the code is pretty specific about
what flexible diaphragm is.  Unless you can prove that the diaphragm is
flexible by calc, I think the plan checker is correct in asking you to provide
rigid diapphragm calcs.  (Some of the cities now provide an alternative to
rigid diaphragm analysis by using the simplified base shear.)  

 

That is the preferred method I am using...... My gripe also includes simple one story steel frames, tube steel is preferred but not accepted in steel frames, but cantilevered tube columns are!! The stresses are so low in the steel frames because the deflection governs.

You indicated "My biggest gripe in general is that one or two story residences
are seismically treated (plan checked) like major structures".  My attitude
has been that the earthquake does not know if you structure is  major or
minor.   It will find the weakest link and create havoc if the link is weak
enough. ( My understanding is that of the total damage in the Northridge
earthquake, half the dollar amount was due to damage to single family homes.)
 Also from the point of view of the client, that single family home is his
"Taj Mahal" and a major structure.

Over 80% of the badly damaged structures I inspected after the Northridge quake (mostly residental and industrial) had shotty workmanship (missing nails, bolts , straps, interrupted chord members by  the plumbers,  missing and/or misplaced diaphragm to wall connections, etc.)
 
Nowadays, even when Structural Observation is not required and/or not specified on the "approved" drawings, some inspectors "request" it anyway, wrongly thinking they are off the hook.
 
ASL