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RE: PCACOL in 2006 SEAOC Sesimic Design manual Vol 3 “Unified Design Procedure”

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One of the significant changes in ACI318-05 is the replacement of old "Strength Design" with the new "Unified Design".

"Unified Design Procedure" used to be in Former App. B of ACI 318-99, but in ACI 318-02 moved to chapters 8, 9, 10 and 18.


One of the highlights of the "Unified Design" is that the Strength Reduction Factor "Phi" has to be computed and does not have a predetermined value.


I've read some of the concrete examples in "IBC 2006 Seismic Manual" and have not seen the update & transition form "Strength design" to "Unified design."

In fact I was at a SEOASC seminar based on "IBC 2006 Seismic Manual", last Saturday in Long Beach, and I pointed out this issue to the speaker covering concrete SMRF.


A warning that the "Column Interaction Diagrams" based on old "Strength Design" are no longer valid and correct for the ACI 318-05 "Unified Design."

You'd need to used the update Diagram only found in new publications/software.


If you need reference for clear description on this subject let me know.

Dr. S.K. Ghosh & Ben Yousefi have had some presentations on ACI 318-02/05, which I found to be the best.

Casey (Khashayar) Hemmatyar, SE
Private e <khemmatyar(--nospam--at)>

-----Original Message-----
From: Szuchuan Chang [mailto:szuchuan(--nospam--at)]
Sent: Thursday, September 27, 2007 12:59 PM
Subject: PCACOL used in 2006 SEAOC Sesimic Design manual Vol 3


I am looking at the interaction diagram of page 252 of the 2006 IBC

Structural Seismic Design Manual, Vol 3.


These are the charts for ACI 318-95.  Over ten years old stuff.

PCACOL 3.6x (per ACI 318-02) would produces very much different kind

of charts.


If 2006 IBC is based on ACI 318-05, shouldn't the charts be changed?