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Re: History of conventional wood framing- update

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Janiele-
 
> Houses that strictly comply with the conventional construction provisions
> of the UBC have historically afforded their occupants with life safety.

How about Apartment buildings, office building,
retail buildings, etc. that are also constructed to
the conventional construction provisions.  Good
performance of low rise wood framed structures isn't
limited only to housing.  The Earthquake does not
know what the occupancy is of any particular
building.  

> However, it is estimated that 75% of the over $12.5 billion in insured
> losses in the Northridge EQ occurred in residential construction.  Taking
> out the apartment complexes constructed over parking that leaves a
> tremendous amount of cracked gypsum board and stucco in low rise houses.
> Since these structures comprise the primary residence and single largest
> financial investment for a large portion of our population, perhaps it is
> appropriate to design them for a higher performance level.

Is the standard the 1994 UBC uses to establish Code
design parameters Life Safety, or Controlled
Damage?  I believe most Engineers and Building
Officials are of the opinion that the UBC provides
only a Life Safety level of protection.  I have seen
many Engineers do evaluations of existing older low
rise wood framed residential structures and cite
them as a life-safety threat due to the fact that it
does not conform to the requirements of whatever the
current Code is.  Then the Owners may spend
thousands of dollars in a retrofit to bring it up to
Code in the belief that conformance to Code provides
them with Life Safety protection. 

Even FEMA 310 does not provide realistic standards
for life safety of wood framed buildings.  If you
run the numbers, almost ANY low rise wood framed
building that does not have plywood on it will come
out as being a Life Safety hazard when held to the
FEMA 310 standards.

Performance based Engineering may be a way out of
this problem.  However, when you look at the new
upcoming code, the current standards for low rise
wood framed structures are pretty much represented
as being life safety standards. 

After an Earthquake there are Engineers running all
over the earthquake zone looking at all the failures
and writing papers and making Code changes based on
what they saw FAIL.  

However, I am of the opinion that an equal amount of
time should be spent on figuring out what structures
survived the earthquake and why, and then make
changes to the Code based on this new information.  

In my opinion, the Code should provide a minimal
life safety level of protection, and any Owner
should have the OPTION to request the Engineer to
design to a higher level of controlled damage or
immediate occupancy.  No one should be required to
design to a standard greater than life safety unless
they want to.

Anyway, that is my 2 cents worth.  I know I am in
the minority on this issue, but it seems so obvious
to me.

Lynn