A beam is a long and a straight piece with a uniform cross-section characterised by the type of supports. These beams are used to support different type of loads. There are different types of beams are available along with the different applied loads. Let’s see each of them.
Types of Beams
- Cantilever Beam
- Simply Supported Beam
- Overhanging Beam
- Fixed Beam
- Continuous Beam
The following images make all the sense what are these different types of beams.
Type of Loads that can be applied to Beams
A beam is usually horizontal, and the applied load is vertical. Following are the different types of loads.
- Concentrated or Point Load: Act at a point.
- Uniformly Distributed Load: Load spread along the length of the Beam.
- Uniformly Varying Load: Load spread along the length of the Beam, Rate of varying loading point to point.
Sign conversion for Shear force and Bending moment
For a simply supported beam, If a point load is acting at the centre of the beam. Imagine a section X-X divide the beam into two portions. See the pic below.
A simply supported beam is carrying a load (point load) of 1000N at its middle point. The reactions support will be equal to 500N(Ra=Rb). The section X-X make the beam into two parts.
The moment of all the forces, i.e., load and reaction to the left of section X-X is Clockwise
The moment of all the forces, i.e., load and reaction to the right of section X-X are Anti-Clockwise.
So this makes the beam a Sagging moment(Concavity). Here the bending moment is Positive. See (a)
If the left portion makes an anticlockwise moment and the right portion of the section makes a Clockwise moment, then it is hogging moment. Bending moment Negative.
Similarly for Shear force is positive when the left portion of the section goes upwards or the right portion of the section goes downwards.
Shear force is Negative when the left portion of the section goes downwards, or the right portion of the section goes upwards.
For the bending moment and shear force diagrams refer to this article here!