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Ground Stability, Foundations and Substructures 99
Columns bear on
junction of beams
Upstand
beams
Reinforced
concrete slab
Figure 3.31 Reinforced concrete beam and slab raft.
Raised timber or concrete
floor formed on raft
Slab reinforced top
and bottom in
both directions
Construction
joint
Reinforced concrete
beams
Figure 3.32 Beam and slab raft with downstand beams.
The floor is constructed with precast reinforced
concrete beams bearing on upstand beams of raft
Slab or raft is reinforced
top and bottom in both
directions
Construction joint
Reinforced concrete
beams
Figure 3.33 Beam and slab raft with upstand beams.
slab over the beams and columns over the intersections of beams to spread loads over the
area of the slab.
On granular soils, upstand beam rafts may be used. Temporary support is necessary to
uphold the sides of the upstand beams. The slab is cast around the necessary reinforcement
and the upstand beams inside temporary timber supports, around reinforcement to produce
the upstand beam raft illustrated in Figure 3.33. With an upstand beam raft, it is plainly
necessary to form a raised timber or concrete ground floor.