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RE: 1997 UBC PROVISIONS FOR WALL PIERS

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Dennis 

The blocking and edge nailing (B&E) for the entire width is required, in my
opinion, in order to be able to qualify each pier as a "mini-shear" wall so
the H/W ratio can be assesses based on the height of the pier. If the B&E
for entire width is not provided, then the pier is still a part of a larger
panel and you have not created a distinct element. Also in order to assess
the drift requirement you will need to measure the deflection of the pier.
Without having a boundary element that would not be feasible since
deflection equations assume edge nailing around the boundary of the element.

Ben Yousefi, SE
San Jose, CA



	-----Original Message-----
	From:	Seaintonln(--nospam--at)aol.com [SMTP:Seaintonln(--nospam--at)aol.com]
	Sent:	Wednesday, September 01, 1999 9:31 PM
	To:	seaint(--nospam--at)seaint.org
	Subject:	Re: 1997 UBC PROVISIONS FOR WALL PIERS

	In a message dated 9/1/1999 10:02:47 AM Pacific Daylight Time, 
	Ben.Yousefi(--nospam--at)ci.sj.ca.us writes:

	<< 1.   Blocking and edge nailing should be provided at the top and
bottom
	 of the pier for the entire width of the pier. (along with some
straps as
	 collectors) >>

	Ben,
	The design example from the February 1998 '97UBC Wood Seminar by
Bill Nelson 
	and Doug Thompson had a good clear example of how to design a
shearwall with 
	openings. 
	I don't think that the blocking adjacent to the sill or header need
be the 
	entire width of the wall, but should be as long as required to
collect the 
	horizontal reaction at these two member which is calculated in the
example. 
	Therefore, the development length will vary according to the
calculated 
	tension.
	I have an example where there is a wall approximately twenty two
feet long 
	with four openings for windows. The openings are 2'-6" x 4'-0" high
with the 
	plate heights at 12'. The calculated shears are very low - around 58
plf, but 
	I choose to sheath the entire wall.  In this case I might make the
blocking 
	continuous although the resulting tension would not need to extend
past one 
	bay of studs.

	There should be a shortcut approach to this as well and possibly it
can be 
	presented to Bill Nelson as a question for discussion on the panel
at the 
	SEAOC Convention. The analysis is cumbersome, to say the least.
Although, it 
	can be simplified by use of a template - excel or Mathcad.

	Dennis