5. Conclusion

Controlling crack openings in reinforced concrete is essential to guarantee its durability. The crack opening considered is that which can be measured on the surface (and which is larger than that existing in line with the reinforcement) under the effect of permanent loads. From a design point of view, as this value is naturally variable, its characteristic value (95% fractile) is considered.

The various possible approaches to the mechanical behavior of concrete all lead to the same conclusion: limiting the stress in steels reduces crack spacing and opening and, for a given percentage of reinforcement, using smaller diameter bars is also favorable.

For certain structures, such as tanks, it is also important to take account of hindered shrinkage deformations.

Finally, beyond the elements presented here, the question...