FINITE ELEMENT SIMULATIONS OF SHRINKAGE CRACKS IN SLAB-ON-GRADE DUE TO RESTRAINTS

Abstract

Due to many advantages of slab-on-grade; especially economy and durability, they are mainly used in industries, garages and pavements for sturdy floor and in residential buildings as well. However, it is such a sensitive one in the formation of cracks mainly due to the restraint to deformation. There are possible restraints which do not allow the concrete for freely volume change; friction between slab and sub-base, the effect of piles and columns, and casting sequence. This thesis aims to collect the data and observe the formation of cracks in slab-on-grade of two factories, mainly due to shrinkage deformation and then verify in the finite element program called ANSYS. The data from two industries, crack width and location, was collected as reference to implement cracking model in the finite element simulation. When simulated in program, the model was adopted from the cracked floor area cut by the contraction joints and the restrained boundary conditions as the floor area is very large. The output strain from the program was compared with the crack formation of reference project. The parametric study was focused on cracking which is due to the influence of casting sequence, the effect of friction between slab and subgrade, and the impact of different lengths ratio of the slab.