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RE: CMU rebar splice

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Actually, the splice lengths went down back at least as far as ACI 530-05. 
Several years ago, when I noticed that the masonry splice lengths varied 
pretty dramatically, depending on which code was being used, I wrote a little 
 spreadsheet to compare the splice lengths for the various codes.  I've 
pasted an excerpt below for your case of 8" block with 1 bar per cell.  You 
can see that ACI 530-05 has the 26" for a #5 bar.  But if you used IBC 06 
ASD, you get your familiar 45".  But if you use the strength provisions of 
the same code, you drop back down to 26".  Maybe after several cycles of the 
IBC and ACI trying to catch up with each other, we've finally converged on 
a consistent length, and it happens to be the one that you're not accustomed 
to.

Splice length in masonry (in inches) for 8" block w/ 1 bar per cell, f'm=1500 
 psi

Bar size		IBC 03-ASD	ACI 530-05	IBC 06-ASD	IBC 06-ASD	IBC 06-Strength
						fs<19200 psi	fs>19200 psi
#3		19		16		15		27		16
#4		25		21		20		36		21
#5		31		26		25		45		26
#6		57		43		30		54		43
#7		79		60		35		63		60
#8		113		92		40		72		72
#9		146		119		46		82		82

-- Joel

the structural alliance
Joel Adair, PE, LEED AP
Principal

-----Original Message-----
From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On 
Behalf Of Steve Gordin Sent: Thursday, October 30, 2014 11:29 AM
To: seaint-seaosc(--nospam--at)mail-list.com
Subject: [SEAINT-SEAOSC] CMU rebar splice

Good morning,

Have you noticed that the CMU rebar splicing per ACI 530-13 was drastically
 reduced?  For 8" CMU, the centered #5 rebars with 3" cover appear to require 
 only about 26" of overlap - while traditionally it was 45" for stress
> =80%Fs…

Am I reading it correctly? Is everybody comfortable with this?

Thanks,

______________________________
V. Steve Gordin
Licensed Structural Engineer
SGE Consulting Structural Engineers
2081 Business Center Drive #105
Irvine CA 92612
949-552-5244
sgordin(--nospam--at)sgeconsulting.com

Truncated 858 characters in the previous message to save energy.

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