Structural Engineering: RE: ACI

Thanks for correcting me on ACI 350. Since I am not a "tank" guy, I don't keep up with it. I only knew about it because I was staff liaison to the 350 committee when work for ACI many, many moon ago.

Regards,

Scott

Adrian, MI

-----Original Message-----
From: William.Sherman@CH2M.com [mailto:William.Sherman@CH2M.com]
Sent: Monday, May 19, 2008 2:20 PM
To: seaint@seaint.org
Subject: RE: ACI - Z cracking

I believe that ACI 318 replaced the z-factor in the 1999 code. There is still a requirement related to spacing of bars to control cracking, but it is less stringent and is based on aesthetics rather than durability.

The ACI 350-01 code retained the z-factor equations to control cracking for durability. The ACI 350-06 code modified the crack control equations, replacing the z-factor equations. The modified equations are based on research by "Frosch" rather than the previous research by "Gergely-Lutz". The equations in ACI 350-06, Section 10.6.4, were reformatted to calculate an allowable steel stress based on bar size and spacing in lieu of the quantity 'z'.

Bill Sherman

CH2M HILL / DEN

720-286-2792

From: Scott Maxwell [mailto:smaxwell@umich.edu]
Sent: Monday, May 19, 2008 12:09 PM
To: seaint@seaint.org
Subject: RE: ACI - Z cracking

Z cracking in ACI 318 went "bye-bye" quite a while ago (I want to say in the 1999 or 2002 edition, but I would have to look it up to be sure). It has remained in the ACI 350 code document to my knowledge (it is a "variant" of 318 for environmental structures...aka tanks...they are now independent of ACI 318, but they still tend to use 318 as a basis, but have choosen not to follow on something...such as dropping the Z cracking method).

Regards,

Scott

Adrian, MI

-----Original Message-----
From: Andrew Kester, P.E. [mailto:akester@cfl.rr.com]
Sent: Monday, May 19, 2008 1:13 PM
To: seaint
Subject: ACI - Z cracking

2005 ACI revised 10.6.4 to give max spacing versus the old Z cracking formula? Sounds like this was based on a lot of recent research. My ole 95 version from college still has the Z cracking formula and Enercalcs older versions use it in the beam design under shear.

Just checking...

Andrew Kester, P.E.
Principal/Project Manager
ADK Structural Engineering, PLLC
1510 E. Colonial Ave., Suite 301
Orlando, FL 32803