In building and architecture, a foundation is the element of an architectural structure that transfers loads from the structure to the ground. Foundations usually serve to receive loads form the superstructure and transfer them to the ground. For this purpose, they need to be realised to be stiff.
The type of foundation used depends on the stress acting on it and on the nature of soil with which it is connected.
A foundation can be of two types:
- shallow foundation such as plinth
- foundation beam and deep foundation such as foundation pile
The foundation most commonly used is that one with isolated plinths where the ground is able to withstand a not very low working stress. Typically, a plinth is made of a cuboid reinforced concrete block with a square or rectangular base, placed under each pillar of the structure and centred with respect to this in order to transfer the load resulting therefrom to the ground.
A foundation pile is an element usually characterised by a solid section, including a tapered end and driven in the ground to be rammed. A pile foundation is used every time it is not possible to employ a shallow foundation since the protruding ground does not have a sufficient load-bearing capacity, it is technologically not possible to implement a shallow foundation (offshore structures, incoherent grounds subject to high filtration gradients, etc.) or the foundation needs to be isolated from the topsoil as it undergoes erosion or other phenomenons changing its physical properties periodically or occasionally.