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Re: Rebar lap lengths

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Sorry, I read too fast and did not pick up on the Class A limitation, it is pretty rare to actually have a class A condition.
 
I do not know about Enercalc, I don't use it.  However it is not necessarily conservative to assume c + Ktr to be 2.5.  If there is a difference using the same equation I would assume this is where the difference will be found.  Review the commentary in ACI and you will see that using 2.5 is actually a max reduction, and that 1.3 to 1.5 is more typical and is the basis of the simplified method.  Unless you are intending to review every single case I would use the simplified values as a lower bound.
 
What value is Enercalc assuming for their computation?
 
 
----- Original Message -----
Sent: Thursday, September 29, 2005 10:22 AM
Subject: RE: Rebar lap lengths

Do you mean the 1.3 factor for class B?  If so, calculated the splice length for both class A and B and got the ratio in error.  If not, is there another 1.3 factor?

 

Jason

-----Original Message-----
From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net]
Sent: Thursday, September 29, 2005 11:08 AM
To:
seaint(--nospam--at)seaint.org
Subject: Re: Rebar lap lengths

 

Are you accounting for the 1.3 factor?

 

 

----- Original Message -----

Sent: Thursday, September 29, 2005 9:46 AM

Subject: Rebar lap lengths

 

Question to all,

 

I know this must sound like a stupid question, but here it goes.

 

I am trying to write a MathCAD sheet for rebar lap lengths.  Typically I have used Enercalc to get these values.  While writing the MathCAD sheet I ran the equation in ACI318-02 (eq. 12-1) by hand for a #6 bar, fy=60000psi, f?c=3000psi, bottom bars, uncoated bars and normal weight concrete.  I also used   (c + Ktr)/db as 2.5 (max by code).  I ran this by hand and on the MathCAD sheet, and received 19.72 inches (class A splice), this caused me concern because Enercalc gives 25 inches.  Just to be safe I looked in the 2002 CRSI Design hand book and checked their tables, for this case I pulled 25 inches of lap, however, these tables are based on the ACI318-99 code. 

 

Am I missing a step, or is there some factors that are elsewhere in the code?  Any help would be appreciated.

 

Jason