Country: United States
Date: May 2006
What is a cantilever used for?
A cantilever refers to an arrangement where something is
supported rigidly at one end only.
This arrangement is not very structurally efficient, as the supporting
end has to be rather bulky to provide the rigidity of support that is
typically needed. That is, it has to be very stiff, and pretty much
the only way to do that is to have more mass or heavier duty structure.
On the other hand, if a cantilever can be used, it permits a lot more
design freedom, both for practical and decorative use. For example, a
deck cantilevered off of the side of a house does not have any supports
underneath, opening up the space for other uses. An equipment support
that is cantilevered off of a mounting surface has open space at one
end to allow for easier maintenance of the equipment.
So that is basically what it is. To see an example of how cantilevers
are used in architecture, research the design of Frank Lloyd Wright's
"fallingwater" on the web. They just finished a restoration project to
keep the large cantilevered room from collapsing. It required massive
anchors and lots of steel cables at the base, resulting in preservation
of the free and open design.
David Brandt, P.E.
A beam is an element supported at both ends,
in a bigger picture, a bridge is an element
that spans a distance, supports a weight,
and is supported at both ends.
When a case arises, say a balcony where the
element, or beam is logically supported
from one end, that element is a cantilever.
The loading and the stresses induced in
the supporting element are analyzed. The
procedures are the same for a cantilever, however
there is more concern for the support, or connection.
A post, or pole is a cantilever. The loading may be horizontal
as opposed to vertical, for the balcony etc.
A cantilever is a projecting beam supported at only one end. It can
be used to make a bridge where at each end a cantilever beam
projects toward the middle. They can then be joined directly or by
a third beam to form the bridge. A shelf bracket is also a
cantilever with the supporting member fastened to the wall and
projecting underneath the shelf. I am sure you can think of many
other uses for this design.
Best, Dick Plano, Professor of Physics emeritus, Rutgers University
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Update: June 2012