Transcript Strip foundations

Advanced Construction Technology
By Professor Chris Gorse – licensed under the Creative Commons Attribution – Non-Commercial – Share
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Strip foundations
These slides should be read in conjunction with Emmitt, S. and Gorse, C. (2010)
Barry’s Advanced Construction of Buildings. Oxford, Blackwell Publishing
Trench or strip foundations
Trench or Strip
a. Strip foundations.
These are used to transfer long continuous loads
(such as walls).
The width and depth of the foundation will depend
on the nature of ground and building loads.
Strip foundation
Strip foundations are suitable for
continuous loads – long loads such as
walls
For cavity wall construction, the building
loads are transferred down the inner
skin of the cavity.
The cavity ties the inner wall to the
external skin providing additional
stability
Strip foundations, at a shallow
depth, are suitable for good load
bearing strata where the
moisture content of the soil is
stable.
Ensure that trees are not planted
close to shallow foundations as
they will reduce moisture content
in the soil causing clays to contract
and the foundation to settle as the
soil shrinks
Strip foundations
Strip foundation with
internal walls and inner leaf
of cavity wall constructed.
Deep strip
Strip foundation are suitable
for continuous loads carried
through walls
Deep strip foundations are
used to penetrate weak
upper layer of subsoil or clay
soils that are susceptible to
expansion and contraction
due to changes in moisture
content.
The foundation rests on the
stable load bearing strata
If expansion of clay is
expected compressible
sheeting is used to stop
clay soils exerting lateral
pressure on the deep
foundation
Foundation depth is increased taking
the base of the foundation to a
stronger load bearing strata or to a
depth where the moisture content of
the ground is unaffected by seasonal
variation
Reinforced wide strip foundation
The tensile reinforcement that is
cast within the concrete base
allows the width of the
foundation to be increased and
the loads to be distributed over a
greater area
Load are distributed over a
greater area reducing the load
per unit area
Steel reinforcement is placed in the bottom
of the foundation where tensile forces are
experienced