beam and slab raft(downstand beam and slab raft foundation

1. An alternative to the solid slab raft
2. Used where poor soils are encountered
3. The beams are used to distrbute the column loads , over the area of the raft , which usually results in a reduction of the slab thickness .
4. THe beams can be upstand or downstand depending upon the bearing capacity of the soil near the surface .
5. Downstand beams will gice a saving on excavation costs , whereas upstand beams create a usable voids below the ground floor if a suspended slab is used .
6. Reinforced concrete or steel columns posioned on beam intersections in the centre , reinforced concrete raft spanning over ground beams
7. The reinforced concrete ground beamm is used on poor soils where the beams are employed to spread the column loads over the raft