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Re: WALL PIER, PILASTER OR COLUMN

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Title: Re: WALL PIER, PILASTER OR COLUMN
Please forgive Bill.  He has gotten so used to talking politics on a structural engineering email list that he has forgotten how to shut off that “mode” (i.e. The “attack dog” mode) when someone has the unmitigated nerve to ask a structural engineering type question.  Thus, you get a smartass comment (the bit about it not being English) and a good definition that tends to glossy over some structural engineering related details.

While his definition is basically on point, it does gloss over some details that structural engineers tend to care about.  As he noted, a pier is can generally be thought of as type of foundation or a “short” column.  And a column is an isolated vertical member, which general support vertical, axial loads but can support lateral loads as well.  And a pilaster is generally considered similar to a column except that it will NOT be isolated (i.e. As Bill noted, it is integral with the wall).

The part that Bill left out is that both the Masonry code (MSJC or ACI 530) and the Concrete code (ACI 318) give a specific definition of a column so as to differentiate it from a pier (or in the case of the Concrete code, a pedestal).

In section 1.6 of the Masonry code, both a column and pier are defined:

Column – An isolated vertical member whose horizontal dimension measured at right angles to its thickness does not exceed 3 times its thickness and whose height is greater than 4 times its thickness.

Pier - 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.

And in section 2.2 of the Masonry code, both a column and pedestal are defined as:

Column – Member with a ratio of height-to-least lateral dimension exceeding 3 used to primarily to support axial compressive load.

Pedestal – Upright compression member with a ratio of unsupported height to average least lateral dimension not exceeding 3.

It should be noted that strictly speaking the Concrete code does not really use the term “pier” for a “short column” as concrete piers are generally considered foundation elements (i.e. Drilled piers or caissons).  Instead, it uses the term “pedestal”....even though most engineers would likely call them “piers”.

Regards,

Scott
Adrian, MI


On 8/11/09 11:22 AM, "Bill Polhemus" <bill(--nospam--at)polhemus.cc> wrote:


This isn't English, it's "Architect-ese," related to Latin.

A Pier can be many things, including a type of foundation, or a "short column." A column itself is a slender vertical support element that is considered to be "independent" of any other parallel element such as the wall itself. A Pilaster is similar to a column, but is integral (or "in line") with the wall.
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