INVESTIGATING THE SHRINKAGE BEHAVIOUR OF REINFORCED CONCRETE SLABS-ON-GROUND

Abstract

Slabs-on-ground are large planes lying on continuous support subjected to defferential shrinkage and loads. Curling or vertical deflection and cracking due to damages of slabs are undesired events caused by differential shrinkage, which limits the service life of the slabs. Typically the slabs-on-ground are exposed to varying relative humidity on the top surface but not at the bottom ground surface, which results in the formation of moisture gradients through the slab, thereby inducing gradient shrinkage, promoting damage and deflection. Referring to service conditions, it is well known that the concrete shrinkage effect tends to be the principal reason for the initial tensile damage to form crack on the top surface and edge curling of slabs-on-ground. Shrinkage strain distribution across the depth of the slab on-ground was modeled and applied as equivalent temperature gradient. This thesis intends to investigate the shrinkage behavior of reinforced concrete slabs-on-ground for different parametric studies using the non-linear finite element analysis software package, Abaqus. The general purpose finite element software Abaqus used to simulate analysis of slab-on groud in this study has no defined program for shrinkage analysis so that equivalent temperature gradient was used to simulate shrinkage distribution. The models are verified by comparing the results with previous experimental studies. Based on the performed parametric studies, upward curling was maximum at corner of free end slabs and steel reinforcement positioned in center of the slab can minimize tensile damage to reduce top surface cracking of slabs-on-ground.