Section 8.6.3/9.5.2.3 Crack Control with Direct Crack Width Calculation
When crack widths are assessed by direct calculation, cracked equilibrium strains are calculated using the equations in 8.6.2.3 assuming that concrete has no tensile strength. The characteristic maximum crack width can be input directly or using the selected "Environment" as noted in section 65.6.11. No limits are imposed on the input crack widths.
This criterion is applied to two-way slabs and other wide cross sections, but will not provide accurate crack width predictions for these wide cross sections when reinforcement is not spaced according to the varying stress patterns across the section. For narrower cross sections with a uniform stress pattern, the bonded reinforcement should be spaced uniformly. For this reason, it may not be appropriate to do a "crack width" onlydesign on full panel strip widths.
The crack-limiting capabilities of appropriately placed bonded tendons are considered, and the balance loading will be considered if included in the load combinations.
w = sr,max(εsm- εcm) ≤ w’max |
εsm - εcm = σscr/Es – 0.6(fct/(Espeff ))(1 + ne peff ) + εcs ≥ 0.6 σscr / Es |