Beams are used to ‘span’ distances, such as the distance between two walls. How well the beam works depends the material it is made from and its shape. In some buildings you can easily see the steel girders that hold the roof up. These are made from different ‘sections’ or shapes and some are named below.

These are very common sections and are easy to remember because they are named after their shapes (look at the names carefully).

Sections like these are not only used for girders in buildings. For example, a bicycle is usually made from circular section, sometimes called ‘tube’. Metal tables are often made from square section tube.

Imagine if you made a table from solid metal. It would be very heavy and expensive. However, tables made from square or circular section are light and cheaper to produce because they are made with less metal.

Below are two reasons for using tube;

1. It is lighter than solid material.
2. It is less expensive.

There is a third reason:

Sections like the ones seen on this information sheet are very strong and less likely to bend and break than solid material.

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