Classifying Structures

Types of Structures

Natural

 Not made by people Occur naturally in the environment

Mountains, spiders web, nests

Manufactured

Built by people Many are modeled after natural structures

Bridges, towers, artificial lakes

Classifying Structures

Mass Structures

Can be made by, piling up or forming similar materials into a particular shape or design.

Mass Structures - Advantages

Held in place by its own weight

Losing small parts often has little effect on the overall strength of the structure

Mass Structures – Examples

Natural Mountains, coral reefs

Manufactured Sand castles, dams and brick walls

Mass Structures - Properties

Not always solid Layered and have hollowed out areas

Great Pyramids of Egypt

Must be heavy enough to stay in place Must not be too heavy to compact the earth

unevenly below it Must be anchored firmly

Frame Structures

Made of a skeleton of strong materials

Then filled and covered with other materials This support the overall structure.

Most of the inside part of the structure is empty space.

Frame Structures - Advantages

They are relatively easy to design and build

Inexpensive to manufacture

 

Frame Structures - Examples

Load-Bearing Walls The walls that support the load of the building.

Partition Walls The walls that divide up the space inside the

building.

Bicycles The frame supports the load it carries on the seat.

Shell Structures

Keeps their shape and support loads without a frame, or solid mass material inside Made of a thin, carefully shaped, outer layer of

material

Shell Structures – Properties

The shape of a shell structure spreads forces throughout the whole structure Every part of the structure supports only a small

part of the load, giving it its strength.

Shell Structure - Advantages

Two main features

they are completely empty, so they make great containers

their thin outside layer means they use very little material

Shell Structure: Disadvantages

A tiny weakness or imperfection on the covering can cause the whole structure to fail.

Flat materials are difficult to form into the rounded shell shape.

Must be very careful when joining pieces, so it is strong and doesn’t collapse.

Shell Structures – Examples

Natural Igloos turtle shell

Manufactured Pop cans Domes in churches and mosques

Mix-n-Match

Some structures are combinations of different types of structures:

Football helmets  Shell structures -to protect the head Frame structure attached in front - to protect the

face. Hydro-electric dams 

Are mass structures Frame structures inside to house the generators

Mix-n-Match Continued

Airplanes  frame structures Shell structure – outside 'skin' gives strength to

and makes it lightweight and flexible.

Domed buildings  combine shell and frame construction