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The safe bearing capacity of soil is the safe extra load soil can withstand without experiencing shear failure.

**Bearing
Capacity of Soil**

The safe bearing
capacity of soil is the safe extra load soil can withstand without experiencing
shear failure. The Safe Bearing Capacity (SBC) is considered unique at a
particular site. But it also depends on the following factors:

� Size
of footing

� Shape
of footing

� Inclination
of footing

� Inclination
of ground

� Type
of load

� Depth
of footing etc.

SBC alone is not
sufficient for design. The allowable bearing capacity is taken as the smaller
of the following two criteria

� Limit
states of shear failure criteria (SBC)

� Limit
states of settlement criteria

Based on ultimate capacity, i.e., shear failure
criteria, the SBC is calculated as

SBC
= Total load / Area of footing

Usually the Allowable
Bearing Pressure (ABP) varies in the range of 100 kN/m^{2} to 400 kN/m^{2}.
The area of the footing should be so arrived that the pressure distribution
below the footing should be less than the allowable bearing pressure of the
soil. Even for symmetrical Loading, the pressure distribution below the footing
may not be uniform. It depends on the Rigidity of footing, Soil type and
Conditions of soil. In case of Cohesive Soil and Cohesion less Soil the
pressure distribution varies in a nonlinear way. However, while designing the
footings a linear variation of pressure distribution from one edge of the
footing to the other edge is assumed. Once the pressure distribution is known,
the bending moment and shear force can be determined and the footing can be
designed to safely resist these forces.

Tags : Civil - Design of Reinforced Concrete Elements - Limit State Design Of Footing

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