Foundation cases

To be continued >

Unified spread footing of an elevator core

The three shear walls of the elevator constitute one element (elevator core) whose foundation is composed of a spread footing reinforced by a grate of rebars placed at its lower surface.

3-D view of elevator core unified spread footing


Unified spread footing of staircase core

3-D view of staircase core unified spread footing

In the case where the foundation of the staircase is composed of a unified spread footing, due to its extremely extensive surface, it is required to place a double reinforcement grate (at the upper and lower surface).

Behaviour of floor supported on ground

The vehicle ramp on ground is an extensive load bearing element which at the same time constitutes its self-foundation. As in every other foundation, the soil condition has a fundamental importance and most of the times in ramps’ case, it is formed at least partially with embankment (polder).

The first case of a floor’s unfavourable behaviour is the subsidence (recess) of the soil under the middle of the ramp’s width and the formation of tensile stresses in the lower fibers. [the deformations shown at the above and the following figure are presented in a large scale].

The second case of a floor’s unfavorable behavior is the subsidence of the soil under the one or the two ramp ends and the formation of tensile stresses in the upper fibers.
In these cases, the ramp must be reinforced with a double wire mesh, one placed at its lower surface and at its upper surface

Behaviour of floor supported on ground

In order to provide the reinforcement with two wire meshes, it is mandatory to use rebar chairs. For ramp widths reaching up to 2.5 m and since there it is possible to cast and vibrate concrete from both sides of the ramp, rebar chairs can be replaced by open-form folded wire meshes (hairpins) or by closed form folded wire meshes which at the same time will provide efficient cohesion of the ramp’s edges.