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Shallow Footings:
Design Considerations
With / Without Reinforcement
Zone of compression in
lightly loaded footings
Typical section
Rebars
Material
Concrete
Plumstone
Bricks
Design Chart:
Bearingcapacitywithrespect to acceptablesettlement
Settlement
Structuralrigidityon differentialsettlement
a) very flexibleb) more rigid
Structuraldesign ofcombinedfootings:
a) idealized beam strips,b) longitudinal beam strip,c) transverse beam strip.
Note:
k = E/Edef . (t/l)3
If k > 1.0 Rigid Footing
Total and differential settlement(Adapted from Bjerrum, 1963)
Settlement
Structure: statically determined
not statically determined - concretenot statically determined - steel
Rigid str. made of reinforced concretestack – smokestack up to 100 m
higher than 100 m
Value (mm) Type Value
Buildings + Structures not sensitive to differential settlement
Methods of leveling the base plate:a) Double Nuts
b) Blocks and Shims
Mat Foundation
Pile-/Shaft-supported Mat Foundation
Mat:Rigid / Flexible
Influence ofsubsoil/rock
stiffness
Coefficient ofSubgrade Reaction:
k = σ / δ(per Winkler analysis)