Raft foundation
As a rule, raft foundation is used as a building’s foundation when the soil has a low bearing ca-pacity.
As shown at the following figure, the ribbed raft foundation reinforcement can be separated into three categories:
(a) slabs’ reinforcement (in yellow color)
(b) slabs’ free edges reinforcement (in blue color)
As shown at the following figure, the ribbed raft foundation reinforcement can be separated into three categories:
(a) slabs’ reinforcement (in yellow color)
(b) slabs’ free edges reinforcement (in blue color)
(c) beams’ reinforcement (in green color)
Reinforcement of a raft foundation with hidden beams
The stirrups placed inside the hidden beams may be two-legged or four-legged (as they are in this example). On other occasions, stirrups with more than four legs can be used.
Yes, the raft foundation increases the the surface area of the foundation, distributing the effective pressure over a greater surface area, effective allowing it to float over the low bearing capacity surface, like a raft. also useful for clay soils where heaving can occur due to changing moisture content.
Beams allow structural integrity and prevent loads from columns to punch down into soil. It also distributes loads from columns evenly across the foundation.