- A built-up beam is also known as compound beam.
- The built-up beams are used when the span, load and corresponding bending moment are of such magnitudes that rolled steel beam section becomes inadequate to provide required section modulus.
- Built-up beams are also used when rolled steel beams are inadequate for limited depth.
- In building construction, the depth of beam is limited by a space provided by the architect.
- Drawing beam of small depth do not provide required section modulus. Therefore, plates are attached to the beams.
- The strength of rolled steel beams is increased by adding plates to its flange which is one of the method forming built-in section.
- The other method is to compound a number of rolled steel sections themselves.
The built-up sections shown in figure’ A’ and ‘B’ are used for heavy loads and small spans.