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What are frame and shell structures?

Different structures have different functions or purposes. The individual parts of any structure need to be selected, arranged and fixed together carefully to make sure the structure carries out its function.

An illustration of a robot with its arms open wide, smiling.

There are two main types of structures.

  • A frame structure is a made from different parts joined together to make them stable and strong. Frame structures can be as simple as a garden fence or something much more complex such as a skyscraper.

  • A shell structure has a thin curved outer layer and is hollow. These structures often are used to hold or protect something. They usually have only a small number of joins or no joins at all.

An illustration of a robot with its arms open wide, smiling.
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Video: What is a structure?

Find out more about shell structures and frame structures in this video.

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Examples of frame structures

A fence

A wooden post and rail fence in a field under a blue sky

A fence is a simple frame structure as it only has a few parts. Its function is to create a without needing any extra support to stay upright.

A fence is strong and stable due to the vertical that are fixed into the ground. Burying these posts further into the ground makes the fence more stable. If they are placed too far apart they will create a weak fence.

Horizontal or panels are attached to the vertical fence posts. Nails or screws are added to create joints.

A wooden post and rail fence in a field under a blue sky

A suspension bridge

Sunrise over the Clifton Suspension Bridge spanning the Avon Gorge in Bristol

Frame structures can be used to make a suspension bridge. It's function is to cross large areas of land or water, carry heavy vehicles and remain standing in difficult environments.

Suspension bridges often have two or more towers and a deck, where the road is placed. This hangs from strong wires called cables. A force called tension is used by the structure. This means the bridge is pulled tight so the weight on the bridge is spread as the cables pull and tighten.

Sunrise over the Clifton Suspension Bridge spanning the Avon Gorge in Bristol

A skyscraper

A photograph of the New York skyline with the Empire State Building rising above a misty city.

A skyscraper is a complex frame structure. It is a very tall building with many stories, or floors. Its function is to provide a large amount of space to work or live in, while only taking up a small area on the ground.

Before the 19th century, tall buildings would have been made with brick or stone walls. The heavy weight of each floor made it impossible to build very tall buildings.

In the 19th century, steel, which is much lighter and stronger, made the building of modern skyscrapers possible. It is now used to construct extremely tall buildings.

A photograph of the New York skyline with the Empire State Building rising above a misty city.
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Parts of a frame structure

See if you can identify the parts of a frame structure.

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Examples of shell structures

A bicycle helmet

A white skateboard helmet

A bicycle helmet is a simple shell structure. The function of a bicycle helmet is to help protect a cyclist鈥檚 head.

The thin curved outer layer of the helmet is usually made from plastic, because it is hard and strong.

Plastic is also light, easy to shape and cheap, making it a good choice of material to construct a helmet from.

A white skateboard helmet

An aeroplane's body

A passenger jet on the runway with its door open and a ladder leading to the open door.

The tube that forms the main body of an aeroplane is an example of a shell structure.

The tube is filled with seats, equipment and the pilot's cockpit. Its function is to remain strong and protect whatever the plane is carrying.

The outer shells of most aeroplanes are made from a metal called aluminium. This metal is strong, lightweight and is to rust.

A passenger jet on the runway with its door open and a ladder leading to the open door.
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Activity: Famous structures

Find out about some famous frame and shell structures in this activity.

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Key words

BoundaryThe line that marks the edge or limit of a space.
FunctionThe purpose of something.
PostsA long piece of wood, metal or other sturdy material that is fixed firmly in an upright position.
RailsA horizontal bar fixed to posts on a barrier or fence.
TensionA force made by pulling something tight.
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Quiz

Test your knowledge of frame and shell structures in this quiz.

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More on Structures

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