The problem of a large FRC slab resting on a Winkler-type elastic foundation and
subject to a transversal load distributed over a small circular area is investigated in
the present work. The mechanical behavior is described by the Kirchhoff
theory of elastic-perfectly plastic plates obeying Johansen’s yield criterion
and associative flow rule. The governing equations within both the inner
elastic-plastic circular region near to the loaded area and the outer elastic
region are found in terms of the transversal displacement and solved in closed
form, under the hypothesis of proportional loading. After the formation of
positive yield lines, namely radial cracks at the bottom side of the plate, the
onset of a negative yield line, namely a circumferential crack at the upper
side of the, defines the load-carrying capacity of the slab on grade. Two
possible configurations are envisaged, depending on whether the circumferential
crack occurs within the inner elastic-plastic region, where radial cracks take
place on the bottom side thus activating a plastic mechanism, or within the
outer uncracked elastic region. The ratio between the subgrade modulus and
flexural rigidity of the plate allows introducing a characteristic length. The
influence of both material and geometrical parameters on the load-carrying
capacity of the plate is then investigated. Based on the analytical results, a
simplified method for the calculation of the load-carrying capacity of FRC
slabs on grade is also proposed and compared with previously developed
models.