A Short Guide to Beam Design

Beam design is practically unheard of outside of professional circles, yet it is one of the most important elements of a building’s design.

Beams come in various different forms and serve a variety of functions.  Furthermore, beam design is applicable to both domestic and commercial construction.

This short guide will explore the basics of beam design by answering the following questions:

• What is a beam?
• What do we mean by the term load?
• What are the different types of beams?
• What materials can be used when constructing a beam?

What is a beam?

Question: what do the following have in common?

• A diving board;
• A tree branch;
• A balance beam

Answer: they can all be classified as beams…

A beam is a long, slender element designed to withstand various loads.  This is achieved primarily through bending.  In essence, beams are required so that a building may support itself and maintain its structural integrity.

What do we mean by load?

Load simply refers to the forces that are exerted onto the beam.  The two principal categories of load that engineers need to consider are:

• Vertical load: this refers to any force that is applied vertically, such as the weight of the materials that the building is made from (i.e. concrete, steel and glass). This is also referred to as ‘self-weight’.  People, furniture and equipment also apply here, as-well as external elements such as the weight of accumulated snow and rain.

• Horizontal loads: essentially, this is any force that is exerted onto a structure horizontally. Horizontal loads arise primarily from external stimuli, such as the weather (i.e. wind) or natural disasters (i.e. earthquakes).

Beam design considers a range of different materials, depending on the structure in question. For instance, beams can be made from steel, wood or reinforced concrete.

What are the Different Types of Beam?

There are four main types of beam:

• Simply Supported Beam;
• Fixed Beam;
• Cantilever Beam;
• Continuously Supported Beam

Simply Supported Beam

As the name suggests, this is the simplest of all the structural elements.  With this type of beam, one end has a fixed hinge whilst the other rests on what is known as a roller.

Changes in temperature can cause the beam to expand or contract, therefore the presence of the roller allows the beam to move and cope with such changes.

Cantilever Beam

This beam is reminiscent of a diving board, with support only at one end.  Cantilever beams allow for overhanging elements and play a pivotal role in the aesthetic principles of modern architecture.

The World famous Fallingwater, designed by the renowned architect Frank Lloyd Wright (1928-1959), offers a superb example of how cantilever beams can shape the aesthetics of a building.

 Fixed Beam

Similar to a simply supported beam, a fixed beam lies evenly between two supporting columns.  As the name suggests, the key difference is that both ends are fixed-there is no room for vertical or horizontal movement.  These are sometimes referred to as built-in beams

Continuously Supported Beam

This type of beam is characterised by having more than two supports-they tend to be hinged at either end and propped up by a central column.

What materials can be used when constructing a beam?

Beams are typically made out of steel, concrete or wood.

Beam material selection depends very much on the type of structure being constructed.  For instance, steel is the go to material for high rise buildings such as sky scrapers, as it has a much higher bending stress (i.e. a measure of the stress along the length of a beam due to bending).

A much higher bending stress allows high rise buildings to cope with greater vertical gravity loads (i.e. self-weight) and horizontal loads caused by wind or seismic activity.

Another option is reinforced concrete.  One of the most popular types of beam material, reinforced concrete is a composite material, made up of steel and concrete.  Reinforced concrete is popular as the two materials combined produce a beam that benefits from both a high compressive and tensile strength.

Our in-house team of charted structural and civil engineers are experts in beam design, regularly contributing to a wide range of commercial construction projects (take the World famous CUBRIC building, for instance). 

We also work with a number of domestic clients, designing the beams required for house extensions and loft conversions. 

If you require assistance with the design of structural beams for an upcoming project, call us on 020 8099 6388 or email us on mail@hlngroup.co.uk.  Alternatively, visit our contact page for information on our regional offices.