Beams are used everywhere. Every structure
that you can think of, bridges, buildings, and monuments are all made of beams. Beams are used not only in the construction
of static structures but also in the construction of moving systems such as the wing of an airplane,
the hull of a ship, or, the chassis of a truck. Bones that make our skeletal structure can
also be considered as beams. Beams play such an important role in our life
that I would say that they are the hidden elements that hold all our structures together.
So it is very important for engineers to understand how beams are loaded, and how to determine
the stresses. Beams, in general, are long, straight members
with a constant cross section. I have a steel tube here. Steel tube is a
type of a beam. Steel tubes are used in the construction of balconies, railings for stair
cases and bicycle frames. Let me show you a box beam. Here it is. The
cross section of this beam is a square. These beams are commonly used in general construction
and in welded steel frames. I would like to show a wooden beam now. Here
it is. This is a timber beam and timber beams are used in home construction and you can
see them in your local hardware stores. Finally I want to show you an I-Beam. I-beams
get their name from their distinctive shape. They are also sometimes known as H-beam or
W-beam. They are available in a variety of standard sizes. An I-beam’s strength can
reduce the numerous support structures. They can resist shear forces and bending moments.
For these reason, I-beams are the most widely used structural members in the world.. Whatever the cross section, or the material
may be, beams are designed to withstand loads. These load can be concentrated or distributed. In a typical beam, loads are applied perpendicular
to the axis of the beam. These are all called transverse forces, and
they create shear and bending in the beams. If the loads are not at right angle to the
beam, beams will also experience axial forces. The primary concern in the design of beams
is finding the maximum shear force, and the bending moment along the axis of the beam. And that’s what we are going to do today.
We will learn how to draw the the shear force and bending diagrams of beams under different
loading conditions step-by-step. Let’s get started.