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RE: '97 code seismic map arrived from ICBO

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I may be mistaken (it hasn't happened yet today), but I believe the 1997 UBC base shears are Ultimate, not Working Stress.

Bill Allen

-----Original Message-----
From:	Harris3803 [SMTP:Harris3803(--nospam--at)]
Sent:	Monday, March 16, 1998 8:04 PM
To:	seaoc(--nospam--at)
Subject:	'97 code seismic map arrived from ICBO

     I just received the new seismic maps for the '97 code from ICBO. I
noticed most of the cities in my area ( Ventura County ) are in seismic source
type B areas. The next step was to see what difference this is going to make .
Most of the buildings i work on are plywood shearwalls or concrete tilt up.  
     For an assumed soil type D ( sec 1630.2.3.2 )  i get E = .22 with rho at
1.0 to E=.33 at rho=1.5  ( sec 1630.1.1 ) . This is 1.6 to 2.4 times the old
V=.138W base shear . I must be making a mistake somewhere. Can someone clarify
the base shear for a two story plywood shear wall house under the described
conditions. Quoting code sections would help.
     The next question is when to start using this. If the '97 code is adopted
three years after the '94 code that would be Jan 1999. If you were working on
a tract that had multiple phases i would think we should be advising clients
now so they don't have to pay for a redesign in future phases or if the
submittal is delayed.

     Thanks in advance.

     Tom Harris,SE
     Thousand Oaks, CA