1. POS
K1a recognize and classify structural forms and materials used in construction (identify examples of frame structures, such as goal posts and girder bridges, examples of shell structures, such as canoes and car roofs, and examples of frame-and-shells structures, such as houses and apartment buildings.

2. Unit D: Structures and Forces
Topic 1 Types of Structures
Topic 2 Describing Structures

3. Careers Associated with this Unit
Engineer
Materials/civil/mechanical
Architect
Construction/carpenter
Project Manager
Welder
Inventor/Designer
Marketing
(Lawyers)

4. Classification of Structures
Two Major types
Natural: not made by humans
Manufactured: made by humans
Three sub-types
Mass
Frame
Shell

5. Mass & Frame Structures

6. Mass Structures
Can be made by forming similar materials into a particular shape or design
Mass structures are held firmly in place by their own weight
If small parts break off, it makes little difference

7. Examples of Mass Structure

9. Layering in Mass Structures
The pieces that make up mass structures are often carefully arranged
Example: The patterns of bricks in a wall
Mass Structures are not always solid
Ex: Power damns may contain rooms that hold generators
Mass structures must be carefully designed, due their weight and size

10. Think of a wall of sandbags that is holding back a flooding river
How do you think that the wall structure could fail?

11. Sandbag Walls Can Fail Because….
The wall may not be heavy enough to stay in place
The wall may be so heavy that the earth below it is pressed down unevenly
The wall may not be thick enough or tight enough, so part of it are pushed out
The structure may not be anchored firmly to the ground

12. Frame Structures in Buildings
Are a skeleton of very strong materials that support the weight of the roof and covering materials
Most of the inside of the building is empty space
The walls are loading bearing and support the structure

13. Other Frames Some objects consist only of a frame
More complex objects have other parts added to the frame

14. Frames can be left exposed
Frames may be hidden under covering material
Frames can be left exposed

15. Problems of Frame Building
Frame structures are easy to design and build
One of the least expensive construction choices
Lightweight frames need to be anchored to the ground
Very tall frames can become unstable if they are not properly braced
Large, complicated projects have many parts that all have to fit together perfectly

16. Shell Structures

17. Shell Structures
Objects that use a thin, carefully shaped outer layer of material to provide strength & rigidity
Strong & hollow
Keep their shape & support loads
Completely empty – make good containers
Use very little building material
Forces are spread through the whole structure and each part only supports a small part of a load

18. Examples of Shell Structures

19. Problems with Shell Structures
Tiny weaknesses can cause the whole structure to fail
Flat materials are not easily turned into a rounded shell shape
Assembling flexible pieces into a shell can be difficult

20. Natural Manufactured Mass Frame Shell Combined type
Examples (copy this chart, we are going to classify the following structures)
Natural
Manufactured
Mass
-beaver dam
-sand castle
Frame
-human skeleton
-stool
Shell
-turtle shell
-cardboard box
Combined type

21. (Sod is grass, roots and dirt cut out of the ground in strips)
Sod House
(Sod is grass, roots and dirt cut out of the ground in strips)

22. Epcot Center
(Disney World)

23. (Primarily Sand, some tunnels)
Ant Hill
(Primarily Sand, some tunnels)

24. Bird Cage

25. Snail Shell

26. House “skeleton”

27. Describing a Structure
Function:
What does it do?
What is it for?
Aesthetics
Attractiveness of design
Safety
Margin of safety- “extra safe” range
Cost (balance with safety)

28. Materials Composite materials Layered Materials
Laminations
Woven and Knit Materials

29. Choosing Materials Cost Appearance Environmental Impact
Energy Efficiency

30. Joints Mobile Rigid Allow movement
Ex. Chains, elbows, door hinges
Rigid
Fasteners: nails, staples, bolts, screws
Ties: string, rope, thread
Interlocking shapes
Adhesives
Melted joints (welding, soldering)

34. Adhesives & Melting

35. Sticky substance that holds stuff together
Adhesives
Adhesive (Glue):
Sticky substance that holds stuff together
Glue may soften in water or when its very hot

36. Melting Welding: Melts pieces together
Soldering: Surrounds pieces with melted material that locks them together

37. Assignments Read Topic 2 pgs 282-292, add to your notes
Activity pg 293 “Design Detective”
Traditional Structures Poster pg 293
Marshmallow Bridge
Review Q’s T1-2 pg 296#1,2, pg 297#1,2,3,5,8