Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 4 SOIL SETTLEMENT
Where δ = differential settlement in the structure
L = horizontal distance between the 2 points where δ is considered.
Skelton and McDonald established that for no architectural damage, θ must be less than 1/300 for
buildings on individual footings. As a guide, reader can refer to Table 4.3 for the typical tolerable
values of differential settlement.
Table 4.2 Typical Values of Tolerable Differential Settlement
Span
Structure
ß
/3
Type of Structure
Settlement
profile
Circular steel petrol or fluid
storage tanks:
Fixed top
Floating top
Tolerable differential
settlement, ß (radians)
0.008
0.002 – 0.003
Tracks for overhead
travelling crane. 0.003
Rigid circular ring or mat
footing for stacks, silos,
water tanks etc.
Jointed rigid concrete
pressure pipe.
One- or two-storey steel
framed warehouse with
truss roof and flexible
cladding.
One- or two-storey houses
or similar buildings with
brick load-bearings walls.
Structures with sensitive
interior finishes such as
plaster, ornamental stone
or tiles.
Multi-storey heavy concrete
rigid framed structures on
thick structural raft
foundations.
(Source: Carter M, [7])
0.002
0.015
0.006 – 0.008
0.002 – 0.003
0.001 -0.002
0.0015
Differential
settlement
Comments
For floating top, value depends on
details of top. Values apply to tanks on
a flexible base. With rigid base slabs,
such settlement will cause cracking and
local buckling.
Value taken longitudinally along track.
Settlement between between tracks is
not usually the controlling factor.
Value is allowable angle change at joint.
This is usually 2-4 times average slope
of settlement profile. Damage to joint
also depends on Longitudinal extension.
Overhead crane, pipes, machinery or
vehicles may limit tolerable values to
less than this.
Larger value is tolerable if most
settlement has taken place before
finishes are completed.
Damage to interior or exterior finish
may limit value.
March 2009 4-11