What Is A Cantilever?
This interesting, rather curious word is a more complicated way of saying “any rigid structural member projecting from a vertical support.(dictionary.com) ” In other words, this is a beam that is actually supported on only one end. The definition also refers to the cantilever being a part of the structure, such as in a bridge, “extending horizontally well beyond its vertical support.”
The word is made up of two parts – “cant” and “lever.” The first is believed to come from an architect’s word for the end of a timber that sticks out of the wall. The second refers to the stick-like beam that might have the appearance of a lever because it is connected or support only at one end. The word first appeared regularly in the late 1600s.
According to construction information, the cantilever format is commonly used so that allows structures to overhang an area with no “external bracing.” A cantilever is often used in certain bridges and in constructing a balcony. Builders sometimes use the cantilever style on a temporary basis during construction, especially if it is not practical to use supports.
A key to the use of the cantilever is that the structural load is on the end of the beam that is not supported. Some comparison can be made between construction cantilevers and airplane wings. The wing of a plane is connected at one end and the load, in the form of the pressure of air etc. is applied to the unattached end.
One of the major concerns in using a cantilever method is the stress that is placed on the structure. Internally, the small fibers, molecules of iron etc. that make up the beam are stressed in two ways. The top portion of the cantilever structure is stretched and pulled, while the bottom area is compressed. Both of these can be excessive in certain situations. That’s why construction engineers, architects and builders take care to choose cantilever beams made from particular materials that will handle stress well.
One of the most common uses for the cantilever style of construction is on bridges. Two sections of the bridge are considered cantilevers. These are built from two sides and are designed to meet in the middle of the spanned area. Engineers and architects understand that this 
style is known to support its own weight quite well. It also frees the builders from having to use “falsework” in the middle of a stream or other spanned area. (Falsework supports the actual structure and is removed when work is complete.)
Some of the common uses for the cantilever, in addition to bridges and airplane wings, are storage shelving, balconies, even furniture and benches that are attached to walls or back supports. Obviously, the material that cantilevers are made from is very crucial. This material must be of the correct type and must be able to handle the compression and stretching described earlier. Quality steel and concrete are often used for this purpose. Cantilever bridges are sometimes designed so that when the opposite sections meet they are pried apart and fitted so that they compress and hold the structure together.
Category: Technology