Referring to page 123 of the code in EC2, BS EN 1992-1-1:2004, note 1 above Table 7.3N indicates that maximum bar spacing for crack control is derived based on $k_1$ parameter being 0.8 and $k_4$ parameter being 1.0. According to crack width calculation in clause 7.3.4(3), $k_1$ is 0.8 and $k_4$ is 0.425. Under stress limitation clause 7.2, $k_1$ is 0.6 and $k_4$ is 1.0. So, what do $k_1$ and $k_4$ refer to in Table 7.3N?

I need to know precisely what the parameters mean because I want to verify my crack width calculation based on clause 7.3.4 to see if they match with what is presented on the table.

crack control


They refer to the factors defined in section 7.3.4 on calculation of crack widths (and whatever corresponding national annex that applies to your case). Section 7.3.3 is intended to be an easy to use summary of section 7.3.4 so that is where you should look for any additional information.

Personally I never use section 7.3.3 because the situations where all those assumptions are actually correct are rare, and making corrections can be more work than just using the equations in section 7.3.4. But that's just my opinion.


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