Steel Beams is considered to be a structural element which
mainly carries load in flexure meaning bending. Usually beams carry
vertical gravitational force but is also capable of carrying horizontal
loads generally in the case of an earthquake. The mechanism of carrying
load in a beam is very unique, like, the load carried by a beam is
transferred to walls, columns or girders which in turn transfers the
force to the adjacent structural compression members. The joists rest on
the beam in light frame constructions.
The beams are known by their profile meaning:
- The length of the beam
- The shape of the cross section
- The material used
The most commonly found steel beam is the I beam or the wide
flanged beam also known by the name of universal beam or stouter
sections as the universal column. Such beams are commonly used in the
construction of bridges and steel frame buildings.
Types of beams
The most commonly found types of steel beams are varied and they are
mentioned below:
- I beams
- Wide flange beams
- HP shape beams
- Special shape non-standard beams
- H beams
- Junior beams
Typical characteristics of beams
Beams experience tensile, sheer and compressive stresses internally due
to the loads applied to them. Generally under gravity loads there is a
slight reduction in the original length of the beam. This results in a
smaller radius arc enclosure at the top of the beam thus showing
compression. While the same beam at the bottom is slightly stretched
enclosing a larger radius arc due to tension. The length of the beam
midway and at the bends is the same as it is not under tension or
compression and is defined as the neutral axis. The beam is completely
exposed to shear stress above the support. There are some reinforced
concrete beams that are completely under compression, these beams are
called prestressed concrete beams and are built in such a manner to
produce a compression more than the expected tension under loading
conditions.
The prestressed concrete steel beams has the manufacturing process like,
first the high strength steel tendons are stretched and then the beam is
cast over them. Then as the concrete begins to cure the tendons are
released thus the beam is immediately under eccentric axial loads. An
internal moment is created due to the eccentric axial load which in turn
increases the moment carrying capacity of the beam. Such beams are
generally used in highway and bridges.
Materials Used
In todays modern construction the beams are generally made up of
materials like:
- Steel
- Wood
- Reinforced concrete
