Analysis of concrete slabs supported on soil

Abstract

A numerical model for material non-linear analysis of concrete slabs supported on soil is described in this work. In this model, the cracked concrete is regarded as cracks with concrete between cracks. The behaviour of the concrete between cracks is simulated by the conventional theory of plasticity. The behaviour of the cracks is defined by their constitutive laws using the concrete fracture properties. Smeared multifixed and rotating crack models are available in the model. Concrete can be reinforced with sets of smeared bars of different materials and geometric properties, as well as with discrete steel fibres. A tension-stiffening model that takes into account the concrete fracture properties and the reinforcement characteristics is used for the reinforced cracked concrete. Main effects of the fibre reinforcement are reproduced in the model, introducing the material fracture energy and a convenient softening law in the crack constitutive law, and using a new stress-strain relationship for the behaviour in compression. Soil supporting the concrete slab is simulated with springs perpendicular to the slab middle surface. The soil non-linear behaviour and the loss of contact between slab and soil are accounted for. Concrete slabs supported on soil are analysed with the model proposed. Safety of wire mesh reinforced concrete slabs and steel fibre reinforced concrete slabs is discussed. A comparison with conventional design methods is performed. The influences of the soil load bearing capacity, as well as the loss contact between soil and slab on the behaviour of slab-soil system are analysed.