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Re: Definition of Pier in ACI 530-02

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Got it now....I guess.....


Joe



----- Original Message ----- From: "Scott Maxwell" <smaxwell(--nospam--at)engin.umich.edu>
To: <seaint(--nospam--at)seaint.org>
Sent: Thursday, August 03, 2006 5:18 PM
Subject: RE: Definition of Pier in ACI 530-02


Yes...pilasters are columns that are built intergral with a wall.

Think of a pier as that is a decrete element like a column but has a
larger plan aspect ratio than a column but is not quite "long" enough to
really fully behave like a wall.  It is kind of a like a mix between a
column and section of wall.  The key thing is that there are specific
reqquirements for piers that are different than columns or walls when
doing strength design (I don't believe that the allowable stress design
offers that same differentiations between the three).

Regards,

Scott
Adrian, MI

On Thu, 3 Aug 2006, Joe Grill wrote:

I thought pilasters were for elements within a wall.



Joseph R. Grill, P.E. (Structural)

Shephard - Wesnitzer, Inc.

Civil Engineering and Surveying



 <http://inet/index.htm>

-----Original Message-----
From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)gmail.com]
Sent: Thursday, August 03, 2006 2:16 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Definition of Pier in ACI 530-02



Piers are generally for thin elements like walls of concrete or cmu. THis is more of a column with the dimensions in both directions being fairly close. See UBC/CBC section 1921 for the wording they use. The oddball part of your thing is the length is only 30" high, therefore its a pedestal. If it were
taller, then it would just be a column.

If it's less than 3x it's thickness, it's a column
If it's greater than 6x it's thickness, it's a shearwall
If it's height is greater than 5x it's length, then its a column again.


Think of a 4 foot stretch of a wall that's 6-8" thick, that's a pier or
"Wall Pier" in this case

-gm

On 8/3/06, Joe Grill <jgrill(--nospam--at)swiaz.com> wrote:

I can't quite get my pea brain around the definition of a pier in the ACI
530-02 document.  It states:



"An isolated vertical member whose horizontal dimension measured at right
angles to its thickness is not less than 3 times its thickness nor greater
than 6 times its thickness and whose height is less than 5 times its
length."



I have a "pier" that is 24"x28"x 30" high.



I see the thickness=24", L=28", h=30"



3 x thickness = 72"



6 x thickness = 144"



5 x L = 140"



The horizontal dimension measured at right angles to its thickness = 28"
which is less than 72" therefore the way I read this this is not a pier.



What am I not getting here?  I see a "pier" as being the same as a
"pedestal" in ACI 318-02, but the definition of a pedestal is clear.



Thanks,

Joe



Joseph R. Grill, P.E. (Structural)

Shephard - Wesnitzer, Inc.

Civil Engineering and Surveying



 <http://inet/index.htm>






--
-gm



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