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[Dr. N. Subramanian]

Sometime ago some one raised the following question and I am giving below the text from ACI web site.

Subramanian
When Does A Column Become A Wall?

Answer :
-->Q. Is there an aspect ratio at which a �column� becomes a �wall?� In designing a relatively tall axial compressive member, I am confused whether it would be appropriate to use the slenderness criteria for columns versus walls.

A. In ACI 318-02 (and previous versions), the design of walls as compression members is governed by the same requirements as columns. Let me give you a little background before pointing to the corresponding Code requirements.

In general, reinforced concrete design approaches can be divided into geometrical and behavioral. The former approach sets dimensional limits for both types of elements (walls and columns); the latter makes no distinction between them when the structural behavior is similar but introduces different requirements where no commonality is observed.

ACI 318 chose the behavioral approach. That is why the flexural design procedures, including the slenderness evaluation, are the same for walls and columns. Shear design procedures are different because the shear behavior of columns is more similar to that of beams, while in walls it varies for out-of-plane effects�similar to slabs�and in-plane effects where the depth-to-height ratio affects the behavior.

This is why there is a section especially for walls in Chapter 11 of ACI 318. Based on this, the ACI Code traditionally has made a distinction only when warranted. Therefore, as a rule, walls can be treated as columns for design purposes unless there is a specific requirement that introduces a difference for wall design, as mentioned for shear.

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[dibesh2063]

Dear Dr. Subramanian,
I would like to express my sincere thanks for his kind reply. I would like to request all our seniors to contribute to this forum by replying to queries for enlightment and guidance for all of us.
with best regards to all,
dibesh

drnsmani[AT]yah... wrote:
Sometime ago some one raised the following question and I am giving below the text from ACI web site.

Subramanian
When Does A Column Become A Wall?

Answer :
-->Q. Is there an aspect ratio at which a �column� becomes a �wall?� In designing a relatively tall axial compressive member, I am confused whether it would be appropriate to use the slenderness criteria for columns versus walls.

A. In ACI 318-02 (and previous versions), the design of walls as compression members is governed by the same requirements as columns. Let me give you a little background before pointing to the corresponding Code requirements.

In general, reinforced concrete design approaches can be divided into geometrical and behavioral. The former approach sets dimensional limits for both types of elements (walls and columns); the latter makes no distinction between them when the structural behavior is similar but introduces different requirements where no commonality is observed.

ACI 318 chose the behavioral approach. That is why the flexural design procedures, including the slenderness evaluation, are the same for walls and columns. Shear design procedures are different because the shear behavior of columns is more similar to that of beams, while in walls it varies for out-of-plane effects�similar to slabs�and in-plane effects where the depth-to-height ratio affects the behavior.

This is why there is a section especially for walls in Chapter 11 of ACI 318. Based on this, the ACI Code traditionally has made a distinction only when warranted. Therefore, as a rule, walls can be treated as columns for design purposes unless there is a specific requirement that introduces a difference for wall design, as mentioned for shear.

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