1. Introduction to Structures & Mechanisms
Warden Ave PS Grade 7 Science
Introduction to Structures & Mechanisms

2. Why do we build?
Humans build structures to meet specific needs. In doing so, they must consider many factors, including not only the functions the structures must perform (What is it going to do? Why do we need it to that?) but also the resources available to build them, the intended lifetime of the structures, and the impact of the structures on the environment.

3. Definitions Structure - An arrangement of parts.
Form – The external appearance of a clearly defined area.
Design – To prepare the preliminary sketch or the plans for a work to be executed, especially to plan the form and structure of: Ex: To design a new bridge.

4. Question for journal
Of the three types of physical structures we’ve looked at, which do you think is the strongest? Give reasons why you believe your assertion is true.

5. The types of structures
There are three types of structures:
Solid Structures: Structures that are build from the inside out.
Frame Structures: Structures that are built up hollow but held together through a series of inter-connected pieces.
Shell Structures: Structures that are hollowed out inside but reinforced through the “skin”.

6. Solid Structures
Coral – Coral is a structure built by millions of organisms. It is essentially a solid structure with no space enclosed by the material from which it is built.
Stone fence – These stones are arranged into a structure that serves the function of defining a property line and setting up a barrier. The wall is solid, and it is the weight of the stones themselves that provide strength and stability to the wall.

7. Solid Structures (cont’d)
Fanshawe Dam – A dam is basically a solid mass structure. Although there may be a small control room enclosed inside, the walls are very thick in proportion to the space inside.
Statue – The statue is made from material poured into a mold and is solid.

8. Frame Structures
Skeleton – The skeleton of any animal provides support for the body. The skin provides a cover, but it is the bones of the skeleton that support the weight of the animal.
New house – In this house under construction, the wooden framework is clearly visible. It rests on a cement block foundation. Drywall will be attached to the framing to enclose spaces. The wall joists and roof trusses support all of the weight of the building.

9. Frame Structures (contd)
Soccer net – The soccer net is a simple frame structure.
Hydro tower – The steel framework of the Hydro tower supports the weight of the structure.
Skyscraper – Reinforced concrete beams and columns provide the structure of the skyscrapers. The weight of the outer shell of concrete and glass hangs on this framework.

10. Shell Structures
Lobster – The shell of the lobster is made of a hard, rigid material containing calcium. For any animal that has an exoskeleton, it is the outer shell that supports the animal.
This stove has a shell of sheet metal.
Water tower – The sphere at the top of the water tower does not contain an internal framework.

11. Shell Structures (cont’d)
Bandshell – Most of the weight of the structure is found in the shell.
Aquatic Centre – The corrugated steel shell is very rigid and creates a structure which contains a large open space.
Computer case – The rigid plastic/metal of the case of this computer is sufficiently strong to protect the internal parts.

12. Solid, Shell, or Frame?

13. Solid, Shell, or Frame?

14. Solid, Shell, or Frame?

15. Solid, Shell, or Frame?