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Re: SEAOC Seismic Design Manual Seminar - Vol. 1

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-----Original Message-----
From: Bill Allen <Bill(--nospam--at)AllenDesigns.com>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
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???????