FORCES STRUCTURES DESCRIBING STRUCTURES STRESS, FATIGUE, FAILURE Grab Bag 10 20 30 40 50.

FORCES STRUCTURES DESCRIBINGSTRUCTURES

STRESS, FATIGUE, FAILURE

Grab Bag

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FORCES -10

The __________________ is an external force that all structures have.

This force occurs due to the WEIGHT of the structure on itself.

FORCES -10

DEAD LOAD

FORCES -20

What is Tension?

Is it an Internal or External?

Can you give a real life example?

FORCES -20

Tension is the Internal Force that causes stretching, pulling, or tightening within a material.

Life Examples: Tug-Of-War (rope tension)

Cables of a suspension bridge

FORCES -30

• What force crushes a material by

squeezing it together?

FORCES - 30

Compression

FORCES – 50

• The external force of the wind, rain, snow and the weight of things that are in or on a structure (People/Furniture) are called …

FORCES – 50

Live Load

FORCES – 40

• Draw Force Vectors (arrows) to label at least 4 different forces acting on a skyscraper

• *Must include BOTH Internal and External Force

FORCES – 40

Wind, Rain, Snow, Hail, Sleet

External: Weight of people and things inside

Weight of the structure on itself (External)Which causes Internal Compression of the materials

Gravity

Structures - 10

A structure that does not occur naturally in the environment and that is created by people is called a __________________________ structure.

Structures - 10

Manufactured

Structures - 20

•Can be made by… piling up or forming

similar materials into a particular shape or

design

Structures - 20

•Solid Structure (also known as a Mass Structure)

Structures - 30

• Structures that keep their shape and support loads without a frame or solid mass material inside, are called _______________. These structures use a thin, carefully shaped, outer layer of material, to provide their strength and rigidity.

Structures - 30

Shell Structures

Structures - 40

WHAT IS A STRUCTURE --- FILL IN THE BLANKS

• Structures have definite __________and _____________, which serve a definite purpose or ___________________.

• Every part of the structure must resist ______________(stress such as pushes or pulls)

Structures - 40

Structures have definite SIZE and SHAPE, which serve a definite purpose or FUNCTION.

Every part of the structure must resist FORCES (stress such as pushes or pulls)

Structures - 50

Besides Aesthetics… what are someof the major considerationsdesigners/architects must considerwhen building a structure.

•Hint * Think of some of the discussion topics you needed to cover in your Ice Hotel Commentaries

OR Think of some of the things you needed to consider in your Design Structure Projects

Structures - 50

Function (What is the Purpose of the Structure)

Form (Solid, Shell, Frame… which will work best)

Materials (What would be the best materials to choose) – pro’s and con’s

Cost (What is the cost of all of the above going to be… what is the budget?)

Safety (Is the design safe, can it support its own dead load… … how much of a live load can it support?)

Describing Structures -10

•The shape, texture, color, type of

material, symmetry and simplicity of

the repeated pattern used in the

design of structures is?

Describing Structures -10

AESTHETICS “LOOKS”

Describing Structures - 20

The following words describe the _______ of a structure?

· containing (substances)

· transporting

· sheltering

· lifting

· fastening

· breaking

· holding


FUNCTION


• What is another name for a frame structure that uses triangles for strength and support?


TRUSS


The combination of compression and tension occurring at the same time results in what force?


•BENDING


What are the 4 principles of stability?


Principles of Stability• 1) Build a firm foundation• 2) Balance Forces• 3) Keep the thrust line vertical (Centre

of Gravity)• 4) Use Rapid Rotation

Stress, Fatigue, Failure - 10

True or False

• Structures are in STRESS only when extremely large forces begin to damage, break, or crack the structure.


False• Structures are in stress as soon as ANY

external and internal force act on the structure causing some change (such as a small amount of internal force).


TRUE OR FALSE ???

The Leaning Tower of Pisa was under a great amount of stress due to the soft ground, compression, sinking of the building, cracking of the building, and forces such as gravity working against it.


TRUE!

Stress, Fatigue, Failure - 30Watch the Following Video… When is the structure stressed? Fatigued? Does it Fail?

https://www.youtube.com/watch?v=lXyG68_caV4


• Stress: External Forces cause some Internal Change

• Fatigue: Torsion and Shear Forces begin cracking and damaging components of the bridge

• Failure: Bridge Collapses


To reduce stress and internal force within the ground we can increase the surface area of a structure against the ground.

Give an example of how this can be done or a life example of a structure that is designed to increase surface area to spread the force of a load.


Snowshoes Snowboards

A Large Foundation (Concrete Slab)

2 Feet on the ground rather than one or tip toes


• What is lamination and how does lamination help reduce possible fatigue of a structure?


Lamination is a method of strengthening a material. By bonding two materials together, you are creating a stronger structure.

Ex: Bonding plastic to paper (laminating a poser for example) will help reduce fatigue, damage… such as rips or tears.

GRAB BAG- 10

• What unit of measurement is used to describe the magnitude (size) of a FORCE?

GRAB BAG– 10

Newtons (N)

GRAB BAG - 20

• The ___________________ is a wobbly, unstable shape. When you push the side (apply force) it flops into a slanted parallelogram. This happens without any of the rectangle’s sides changing length.

GRAB BAG – 20

RECTANGLE / SQUARE

GRAB BAG - 30

Describe Corrugation

What is a corrugated material?

GRAB BAG – 30

• Corrugation is the addition of arches or ridges within a material to allow the material to better resist the internal force of compression.

• * Arches spread the force evenly throughout and strengthen the material

GRAB BAG - 40

GRAB BAG – 40 Dead Load:Weight of the Train on itself and on the tracks

Live Load: Weight of the load Put in to the train cars

Gravity

Thrust of the train forward

Friction acting against the train on the tracks

Normal Force of the ground back up

External Forces: Wind, Rain, Sleet

Compression within the tracks

GRAB BAG - 50

• Choose one of the following Sports or Activities and as a team draw a FORCE DIAGRAM on the board.

• The Diagram must include at least 3 External Forces, 1 Internal Force

• You must also choose 2 Structures needed for the sport and label their structural form (Solid, Shell, Frame, or Combination)

Snowboarding, Volleyball, Tennis

Quidditch , Jumping on a Pogo-Stick, Rock Climbing

GRAB BAG – 50

Snowboarding, Volleyball, Tennis Quidditch , Jumping on a Pogo-Stick,

Rock Climbing

FORCES STRUCTURES DESCRIBING STRUCTURES STRESS, FATIGUE, FAILURE Grab Bag 10 20 30 40 50.

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