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RE: SEAOC Seismic Design Manual Seminar - Vol. 1

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With regards to definitions, I'm not exactly sure if it is clear.

In the definition of "h sub x" it says: "h sub x is the element or component
attachment elevation with respect to grade."

O.K., with regards to wall design, is it "h sub x is the element elevation
with respect to grade" or is it "h sub x is the element attachment elevation
with respect to grade."? If it is the former, then the term varies with
height. If it is the latter, then it does not.

What word(s) does "or" apply?

However, it was made explicity clear in the seminar, regardless of the
wordsmithing, the intent of the author was to average the values and to
apply a uniform load over the height of the wall.

These comments illustrate how a single line in the building code can be
interpreted different ways.


Bill Allen, S.E.
Laguna Niguel, CA

> -----Original Message-----
> From: Ed Workman [mailto:eworkman(--nospam--at)]
> Sent: Monday, August 09, 1999 12:42 PM
> To: seaint(--nospam--at)
> Subject: Re: SEAOC Seismic Design Manual Seminar - Vol. 1
> -----Original Message-----
> From: Bill Allen <Bill(--nospam--at)>
> To: seaint(--nospam--at) <seaint(--nospam--at)>
> Date: Monday, August 09, 1999 11:29 AM
> Subject: RE: SEAOC Seismic Design Manual Seminar - Vol. 1
> >1. Designing a masonry or tilt wall in accordance with section 1632.2
> >I had previously posted some questions on this list and a
> thread ensued
> >regarding the design of mass walls to comply with this code
> section. Some
> >engineers, including myself, interpreted the section to
> require a varying
> >distribution of load based on the minimum (0.7*Ca*Ip*Wp) to
> a height of
> >0.367*hr then increasing to ap*Ca*Ip*(4)*Wp/Rp at the roof
> level. Others
> >suggested that the wall force be a uniform force based on
> the average of
> the
> >two values. Based on the seminar and design examples, the
> latter method is
> >the one that was used
> I disagree with either/both, based on code language:   EQ
> 32A-1 has no
> terms which vary with height
> EQ 32A-2 has two terms of interest; a sub p which is a
> constant for a given
> region, and a variable h sub x divided by h sub r.  These two
> terms are
> defined under the equations. First,  h sub x  is
> ",,,attachment elevation
> with respect to grade..".   h sub r is "..structure roof
> elevation with
> respect to grade"
> Except for a sloping site or sloping structure  these two terms are
> reasonably constant values. And for a single story structure,
> such as a
> warehouse, tilt-up, retail, etc. h sub x is equal to h sub r, and the
> parenthetical term reduces to 4.0 ( similar to  EQ 32-1 ).
> No averaging and one calculation for a typical situation :
> 4*Ca*Ia times  a
> sub p divided by Rp
> and a sub p depends on location parapet or not
> Now what have I missed here???????