Beam – Definition and Types

A beam is a structural member used for bearing loads. It is typically used for resisting vertical loads, shear forces and bending moments.

Types of Beams:

Beams can be classified into many types based on three main criteria. They are as follows:

1. Based on geometry:
   1. Straight beam – Beam with straight profile
   2. Curved beam – Beam with curved profile
   3. Tapered beam – Beam with tapered cross section
   4. Based on the shape of cross section:
      1. I-beam – Beam with ‘I’ cross section
      2. T-beam – Beam with ‘T’ cross section
      3. C-beam – Beam with ‘C’ cross section
2. Based on equilibrium conditions:
   1. Statically determinate beam – For a statically determinate beam, equilibrium conditions alone can be used to solve reactions.
   2. Statically indeterminate beam – For a statically indeterminate beam, equilibrium conditions are not enough to solve reactions. Additional deflections are needed to solve reactions.
3. Based on the type of support:
   1. Simply supported beam
   2. Cantilever beam
   3. Overhanging beam
   4. Continuous beam
   5. Fixed beam

Classification of beams based on the type of support is discussed in detail below:

1. Simply supported beam:

A simply supported beam is a type of beam that has pinned support at one end and roller support at the other end. Depending on the load applied, it undergoes shearing and bending. It is the one of the simplest structural elements in existence.

The following image illustrates a simply supported beam.

Simply Supported Beam (SSB)

2. Cantilever beam:

A cantilever beam is fixed at one end and free at other end. It can be seen in the image below.

Cantilever Beam

3. Overhanging beam:

A overhanging beam is a beam that has one or both end portions extending beyond its supports. It may have any number of supports. If viewed in a different perspective, it appears as if it is has the features of simply supported beam and cantilever beam.

Overhanging Beam

4. Continuous beam:

A continuous beam has more than two supports distributed throughout its length. It can be understood well from the image below.

Continuous Beam

5. Fixed beam:

As the name suggests, fixed beam is a type of beam whose both ends are fixed.

Fixed Beam