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Re: CalTrans Screw Up/ engineering judgement

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  >>  Take the example of plywood shear wall height to width ratios. If you
are using 3.5 :1 as allowed by the '94 code , it is adequate. The '97 code
requires 2:1 which my experience reviewing over 1000 Northridge E.Q.
damaged
houses makes me feel is more appropriate. Therefore when an engineer uses
 experience / Judgement  and decides to use 2:1 ratio now , before the '97
code is adopted , he may be judged by some to be engineering above
"adequate"
and should be "held accountable ". Where is engineering judgement?<<

Another example is the use of gyp board - the 94 Code allows the use of gyp
board in Zones 3 and 4 as long as you cut the allowable shear load by 50%
(UB TAble 25I). Theoretically adequate, even in Zone 4. But those of us who
saw houses torn to pieces after the Northridge Earthquake would beg to
differ. I do NOT spec gyp board on new shear walls. It may be adeqate but
it's not satisfactory.

Kate O'Brien, P.E.
Simi Valley (California