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RE: Reinf. for excess conc. col size

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Joe – I remember the general consensus being that the bars should be placed where they would do the greatest structural benefit.  In nearly all cases, that would be by arranging the bars at the far edges of the column, minus your clear cover.  I don’t see what the argument would be for doing it otherwise.


Eli Grassley

PSM Engineers



-----Original Message-----
From: Joe Grill [mailto:jgrill(--nospam--at)]
Sent: Thursday, November 04, 2004 2:08 PM
To: seaint(--nospam--at)
Subject: Reinf. for excess conc. col size


Sorry, for this question, as I remember someone asking this or something very similar in the recent past.  I tried to search the archives but for some reason I could not gain access.  If you have a concrete column or in some cases a pedestal where the concrete area is much larger than is required for strength, then the minimum required reinforcing can be reduced per ACI 318 to what is required for a reduced section but not less than 50 percent.  My question is does the reduced amount of reinforcing then need to be arranged in a pattern for the smaller required section or can it be spaced around the larger section.  For example if a column is 24” square, 1% steel would require 19, or let’s say 20-#5 bars.  But if a 12” square column would have worked then 10 #5 bars could be used per ACI.  Should the #5 bars be arranged in the 24” column as if it were in a 12” column?  Wow, I’m having a hard time explaining this, but I’m sure you all understand.


Joe grill


Joseph R. Grill, PE (Structural)