1. The Structures in our Lives
Unit 1
Structural Engineering
Mr. Graves

2. Any assemblage of materials which is intended to sustain loads
What Is a Structure?
Any assemblage of materials which is intended to sustain loads

3. Lets break it down – key words
Assemblage – a group of things gathered together
Material – what a thing is made of
Sustain – carry the weight of or withstand
Load – the weight a structure bears or the stresses put upon it

4. Now – what is a structure?
A group of things something is made of which must carry weight and withstand the stresses put upon it

5. Are they Structures? Drop of water Mosquito Skateboard Tree Chair
Pair of glasses
Shoe
Hockey stick
House
Human being
Thumb tack
Piece of paper
Bridge
Tunnel
Space shuttle
A planet

6. Natural or Man-Made? Man-Made - produced by humans
Adapts through technology
Changes instantly by taking control of the situation
Expense – Cash Cost
Failure = financial ruin
NATURAL – produced by nature
Adapts through evolution
Changes through time and situation
Expense – Energy
Failure = death

7. Natural Structures – Team Activity
You will work with a partner – given 5 minutes to prepare and 1 minute to present
Describe your structure
Describe what makes it unique
Identify the forces acting on it
Identify why it is the way it is

8. Man–Made Structures Team Activity
You will work with a partner – given 5 minutes to prepare and 1 minute to present
Describe your structure
Describe what makes it unique
Identify the forces acting on it
Identify why it is the way it is

9. Modeling Nature What can we learn and how do we model nature?
Spider and artificial silk
Velcro and a briar on clothing
Dolphin chirps and sonar
Lobster and a suit of armor
Earthworm and a train
Plant cell and a vehicle operating on a hydrogen fuel cell
Eiffel Tower and a human skeleton
Ribbed low-drag material and shark skin

10. Biomimetics
The technological outcome of the act of borrowing or stealing ideas from nature

11. Engineering
The science concerned with putting scientific knowledge to practical use

12. To Build Scientific Knowledge You must take time to UNDERSTAND
Observe – use you senses and ask why…
Think – what makes it work
Organize – where does it fit in
Apply – how can you use this new found knowledge

13. Structural Forces

14. Internal Forces – act within materials
Forces exerted by on part of a structure to another. The initial force may be internal or external.

15. Tension – A force that pulls or stretches
Two people pulling on a rope
A fish pulling on a line
A car towing a trailer
A kite string

16. Tensile Strength – A materials ability to withstand tension without breaking
A fishing line that can support the weight of the fish
A truck and hitch that can tow a trailer
A bungee cord that can support the jumper
A kite string that can withstand the wind force

17. Compression – A force that pushes or squeezes
Weight of a person on stilts
Weight of a skyscraper on the ground
Weight of the bar on a lifter
Weight of you on your sneakers

18. Torsion - Bending – When a straight member becomes curved
Torsion - Bending – When a straight member becomes curved. One side in tension – the other in compression
Failure of the Tacoma Bridge
Dancers stretching
Shaping a piece of wood
Skis conforming to the terrain

19. Shear – A force that causes parts to slide past one another
Cutting action of shaving
Cutting the wool of an animal
Wind shear – winds sliding past each other
Action of scissors

20. External Forces – called a Load
Caused by the physical weight of a structure or an environmental source such as wind, water, or temperature.

21. Dead Load – weight of the structure itself
The materials that make up a house
The materials that make up a bridge
The materials that make up an oil rig
The materials that make up a ship
The materials that make up a person

22. Live Load – A load that changes or moves
Person carrying something
Trees acted on by wind
Snow on the roof of a building
Furniture in your house