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RE: Concrete Cracks.[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: RE: Concrete Cracks.
- From: "Silva John (sj)" <Silva(--nospam--at)hilti.com>
- Date: Mon, 18 Dec 2000 17:20:06 -0600
Since you asked... ACI 224 (Control of Cracking) used to list 'tolerable' crack widths for well-designed R/C structures, depending on the exposure condition. For interior (dry) exposures, a width of 0.016" (0.41 mm) was given. This correlates reasonably well with the EC3, which limits interior cracks to 0.3 mm. You can arrive at the same number by working backwards with the (now defunct) Z factor of 175 in ACI 318 for min. flexural reinforcement (see 318-95 10.6.4). ACI 318-99 has dispensed with the Gergely-Lutz equation and Z factors. Interestingly, in the commentary, you now find the following statements: "The role of cracks in the corrosion of reinforcement is controversial. Research shows that corrosion is not clearly correlated with surface crack widths in the range normally found with reinforcement stresses at service load levels. For this reason, the former distinction between interior and exterior exposure has been eliminated." and "The new provisions for spacing are intended to control surface cracks to a width that is generally acceptable in practice but may vary widely in a given structure." Regards, John -----Original Message----- From: npitera(--nospam--at)mmm.com [mailto:npitera(--nospam--at)mmm.com] Sent: Friday, December 15, 2000 09:11 AM To: seaint(--nospam--at)seaint.org Subject: Concrete Cracks. In concrete, there are cracks, and then there are CRACKS. For beam shear cracks, at what width limit does one consider the crack to be "hairline",0. 003",0.005" 0.007"? Any comments are great appreciated. Regards, Nick.
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