2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference
Dr. M. Reza Kianoush, Ryerson University
The design criteria in reinforced concrete tank walls subjected to temperature and shrinkage effects are important due to problems associated with cracking and leakage. There are major debates and disagreement on the amount of minimum reinforcement proposed in current codes and standards for this purpose. The current design guides are based mainly on engineering judgment and past performance of these structures. In this study, the cracking behavior of reinforced concrete (RC) tank walls subjected to temperature and moisture variations is evaluated using the finite element (FE) method. Three-dimensional shell elements are used to discretize the tank walls with reinforcement layers defined as smeared layers. The non-linearity of concrete is defined using the brittle cracking constitutive model. The FE model is verified by comparing the crack width and crack pattern of a previous experimental study. The influence of reinforcement behaviour (linear vs non-linear) on crack width is discussed. Cracking behavior of single walls is compared with 3D full tank models. It is shown that taking the steel nonlinearity into account could have a considerable effect on crack width. Simulating the entire tank as opposed to a single wall show some differences on the crack width and pattern. The influence of tank wall dimensions, reinforcement ratio, climate and concrete strength is demonstrated on the width of developed cracks. Design recommendations are provided proposing the minimum amount of reinforcement ratio required to control shrinkage and temperature cracking in RC tank walls.