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[SEAOC] Re: [SEAOC] Fwd: Conventional construction provisions

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BTW, in addition to my comments to Ray's message I would like to add one 
or two observations from the damage that I inspected from Northridge.

1. One home in Woodland Hills appeared to be constructed according to an 
engineered set of plans. This was evident from the use of very heavily 
sheathed interior shear walls. The one interior wall I inspected was 
sheathed both sides with 15/32" Structural II plywood and nailed with 
10d nailing at 4:4:12. Simpson HD15's (or possibly 20's) where attached 
at each end and anchor bolts where assumed sufficient since the wall was 
not open to inspection. The wall was set on a foundation that was at 
least three feet wide, but could not be verified by sight for depth.
The kicker was that the top plate of the wall was nailed to the ceiling 
rafters and this is where it stopped. There way about three feet of 
space between the top of this wall and the roof diaphragm. 
The location of the wall suggests that it was designed for about 50% of 
the tributary shear, but since it wasn't connected to the roof (and 
assuming that a gypsum ceiling was not used to transfer shear from the 
another portion of diaphragm down to the wall) it was useless. 

Structural Observation requriments may have prevented this from 
happening. If this contractor/framer did not understand how to connect a 
shear wall, how would a simple framer who builds under conventional 
framing requirments know the engineering principles for shear transfer?

2. How many hundreds of stucco failures occured? How much damage was 
caused from plywood shear wall deflections exceeding code story drift of 
0.005h? Too much from what I saw. 

Finally, how can ICBO publish codes to allow non-professional to 
construct even low risk structures when the engineering community can't 
enforce even decent construction practice?

Dennis

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