Control of cracking in concrete tanks and silos

Cracking inevitably occurs in reinforced concrete tanks and silos. Temperature variation, shrinkage or swelling normally produce stresses that are sufficiently high to produce cracking. Provision of prestressing can partly prevent cracking or reduce crack width. Cracking is accompanied by stiffness reduction, causing the internal forces due to temperature, shrinkage or swelling to drop significantly. Thus, these effects produce higher internal forces if the prestressing level is increased in an attempt to minimize cracking. Therefore, it is beneficial to use partial prestressing, allowing cracking to occur due to these effects, while controlling the width of cracks by provision of an appropriate amount (to be discussed in this chapter) of non-prestressed reinforcement.