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Table of Contents 2

Unit Intro: Famous Structures 3

Lesson 1: Classifying Structures 4

What Are Structures? 5

Types of Structures: 7

Lesson 2: Forces and Loads 10

Internal and External Forces 12

Load 13

Types of Load 13

Lesson 3: Mass, Weight, and Centre of Gravity 14

Quick Recap: 14

Mass vs. Weight 15

The Relationship Between Mass and Weight 15

Stability and the Centre of Gravity 16

Lesson 4: Structural Design Components 17

Beams 18

Supporting A Beam 19

Cantilevers 19

Lesson 5: Structural Failure 22

Unit Intro: Famous Structures

Insert a picture of a famous structure in the space below.

Why did you select this structure?

Think of 3 things that make this structure special.

●

●

●

Lesson 1: Classifying Structures

Nelson Video - Big Ideas

Big Ideas:

● Structures have a purpose

● The form of a structure is dependent on its function

● The interaction between structures and forces is predictable

Key Vocabulary:

Words Definition

Structure Something made up of parts that work together for a

specific purpose

All structures have a form and a function

Form The physical description of a structure (size, shape,

material)

Function The job or purpose that the structure does

Solid structure They are made up of one piece of strong material

Frame structure Frame structures are composed of a framework of parts

that are fastened together to provide strength.

Shell structure Shell structures are hollow structures that require very

little material for their construction, making them quite

light.

Combination

structure

structures are a combination of two or more types of

structures.

Textbook Links:

Textbook glossary

Chapter 10 Textbook

- Focus on

- 10.1 - Structures All Around Us

- 10.3 - Classifying Structures

Guiding Questions:

This lesson will cover the following content. Do not complete the questions at this point.

This section is to be used as a review before the unit test.

1. What is a structure?

2. How can you identify the form and function of a structure?

What Are Structures?

A structure is something that you can see and touch, which can be

man-made or found in the natural environment.

Your body, for example, is a structure, as is a skyscraper and a tree. Each

structure has a basic shape called the form and a function, which is the

job it is meant to do.

The purpose or function of any structure is to handle a load or force. This

could be either a dead load or a live load. A dead load is a permanent force

that puts stress on the structure, like the force of its own weight. A live load

is a force that changes, like the number of people inside a structure or the

amount of wind blowing in it.

Look around the classroom and select several different structures. Explain

each structure’s form and function.

Structure Description of Form Description of Function

Binder Made from plastic and

metal

Rectangular shape that

opens like a book

Used to hold papers

Natural or Manufactured?

We can also classify structures by the materials they are built from,

specifically whether they are natural or man-made. Natural structures occur

naturally in the environment, like a coral reef or a mountain, both mass

structures built over time.

Manufactured structures are often made to mimic natural structures.

However, they are built by people, like a bridge or a hydro dam.

Types of Structures:

When we classify structures by form and function, we can put them into

three categories. These are: solid, frame, and shell structures.

Solid structures

Solid structures are also called mass structures

because they comprise one piece of strong material.

A solid structure relies on its own mass to resist the

forces that may be placed upon it. For example, a

rock (natural) or a brick (manufactured) have both

been used throughout history to create buildings

because they can withstand the forces of nature better.

Frame structures

Frame structures are composed of a

framework of parts that are fastened together

to provide strength. These structural

components are joined together to create

either a 2-dimensional or 3-dimensional form

that can be either left as a frame or covered

by a coating. Some examples of frame

structures include a spider web (natural), a

tennis racket (manufactured), a bat’s wing (natural), and an umbrella

(manufactured).

Shell structures

Shell structures are hollow structures that require very

little material for their construction, making them quite

light. The strength of these structures is found in the

outside shell, which holds the whole object together,

making them good containers. Examples of shell

structures include: a mug (manuctured) and a bee’s

honeycomb (natural).

Some structures are a combination of two or more

types of structures. For example, a house uses

solid structures (boards and nails) to create a frame

structure. These combined structures are used

frequently in consumerism, especially if a product

needs to be shipped, as it is usually in a box or

wrapped in plastic.

Lesson 2: Forces and Loads

Big Ideas:

● Structures have a purpose

● The form of a structure is dependent on its function

● The interaction between structures and forces is predictable

Key Vocabulary:

Words Definition

Force A push or pull

Magnitude The size or strength of a force

Direction The position that the force is going toward

External Force Forces that act on a structure from outside

Gravity A pulling force that acts to pull objects to the centre

of the planet

Internal Force Forces that act between two different parts of a

structure

Tension A pulling force

Compression A pushing force

Torsion A twisting force

Shear Two opposing forces (ex. Using scissors)

Textbook Links:

Chapter 10 Textbook

- Focus on

- 10.2 - Forces

- 10.4 - External and Internal Forces

What are Forces? (What is a Force)

A force is a push or pull upon an object. It can be

applied to a structure externally or internally.

Any force has a magnitude (size or strength) and

direction.

When the forces acting on an object have equal

strength and act in opposite directions, they are

called balanced forces. Balanced forces do not

cause a change in motion. Unbalanced forces do

not cancel each other out and will cause an object to change its motion.

Force diagram Balanced (Y/N) Net Force Direction

No

(moves)

(2N + 14N)

= 16N

East or right

Yes

(does not move)

0N N/A

Yes

(does not move)

0N N/A

No

(will move)

4N West or left

No

(will move)

(6N + 3N)

=9N

East or right

Internal and External Forces

External forces are forces that act on a structure from the outside.

● Gravity is an external force that acts on all structures.

Forces that act between two different parts of a structure are called

internal forces. This year, we will focus on four types of internal forces:

tension, compression, torsion, and shear.

● Tension: caused by pulling one or both ends of a structure

● Compression: caused by pressure on a structure, which presses or

squeezes it

● Torsion: caused when a structure is twisted

● Shear: occurs when forces pull or push in opposite directions within a

structure

Load

When designing a structure, all the forces that will act on that structure

need to be considered. The force acting on a structure is called the load.

Types of Load

● Dead load: caused by the weight of the structure itself

● Live load: caused by the weight of the objects that a structure

supports

● Dynamic load: caused by forces other than the force of gravity.

Moving water and high winds are examples of dynamic loads

Lesson 3: Mass, Weight, and Centre of

Gravity

Big Ideas:

● Structures have a purpose

● The form of a structure is dependent on its function

● The interaction between structures and forces is predictable

Textbook Links:

Chapter 10 Textbook

- Focus on

- 10.2 - Forces

- 10.4 - External and Internal Forces

Key Vocabulary:

Words Definition

Mass Mass is the amount of matter in an object

Mass is measured in grams (g) and kilograms (kg)

Weight Weight is the force of Earth’s gravity acting on an object

Weight is measured in Newtons (N)

Gravity Gravity is an external force that acts on all structures.

This can be measured in N/Kg or based on acceleration

m/s

2

Quick Recap:

● A force can be applied to a structure externally or internally

● Any force has a magnitude (size or strength) and a direction

● Forces are generally described as a push, pull, or twist

External forces are forces that act on a structure from the outside

● Gravity is an external force that acts on all structures

Forces that act between two different parts of a structure are called

internal forces

● The four internal forces that we will concern ourselves with are

tension, compression, torsion, and shear.

Mass vs. Weight

We often use “mass” and “weight” interchangeably.

● For example: a grocery store package might say that a hamburger

patty weighs 200g

In Science, however, mass and weight have different meanings and units of

measurement.

● Mass is the amount of matter in an object

○ Mass is measured in grams (g) and kilograms (kg)

● Weight is the force of Earth’s gravity acting on an object

○ Weight is measured in Newtons (N)

The Relationship Between Mass and Weight

Weight (N) = mass (kg) x gravity (m/s

2

)

The gravitational pull on Earth is 9.8m/s

2

If 1lb = 0.45kg:

- What is your mass in kg? 600lbs x 0.45 = 270kg

- What is your weight in N? 270kg x 9.8m/s

2 = 2,646N

Calculate your weight on other planets

Complete the Force Calculation worksheet

Stability and the Centre of Gravity

Stability is the ability of a structure to maintain, or regain, a stable position

when external forces act on it.

The centre of gravity or centre of mass is the point around which a

structure’s mass is equally balanced in all directions.

The centre of gravity must lie directly over the support base to maintain

stability. Stability decreases as the centre of gravity rises. If the centre of

gravity rises higher and is no longer above the support base, the object will

fall over.

What is Acceleration?

How did Einstein make connections to acceleration and gravity?

Downhill cycling and gravity

Lesson 4: Structural Design Components

Big Ideas:

● Structures have a purpose

● The form of a structure is dependent on its function

● The interaction between structures and forces is predictable

Key Vocabulary:

Words Definition

Beam A horizontal structure designed to support a load

Cantilever A beam supported at only one end

Truss A network of beams arranged in triangles

Arch A curved structure used to span a space while

supporting a load

Dome A shell structure that looks like a top half of a

sphere

Types of Bridges

Textbook Links:

Chapter 11 Textbook

- Focus on

- 11.1 - Stability

- 11.2 - Making Structures Strong: The Beam

- 11.4 - Making Structures Strong: The Truss, Arch and Dome

Beams

A beam is any reasonably level structure that is designed to support a

load.

The frame of a typical doorway consists of a horizontal upper beam and

two vertical supports.

On its own, a beam may not support a large load. Some beams can bend

or break if their load is too great. Beams can be strengthened in several

ways.

● One way is to change the material that a beam is made of. A beam

made of balsa wood is not as strong as steel.

● Beams can be made out of many different materials, such as wood,

stone, concrete, or steel, depending on the load requirements of the

structure.

● Choosing the right material is important in building a strong and

stable structure.

● Steel is stronger than wood, but steel is also heavier.

● An engineer must consider strength and mass when selecting the

material for any structure.

Supporting A Beam

Adding structural support also strengthens a beam.

● A tie is a structural support that is part of a

framework and is designed to resist tension forces. A tie is

usually set at an angle between a beam and its support

base (the wall in this example).

● A strut is similar to a tie, but it is placed

below a beam where it provides resistance

to the forces of compression.

● A gusset is a flat, plate-like device, often

triangular, that supports a beam by

reinforcing the connection between the

beam and its support base.

Cantilevers

Beams are not always supported at both ends.

A cantilever is a beam that is supported, or fixed at only one end. A branch

on a tree and a diving board are examples of simple cantilevers.

Cantilevers are very common. Canopies over entrances to buildings and

apartment balconies are also examples of cantilevers.

The Truss

● A truss can be used as a bridge or a cantilever and for many other

applications

● Truss – A network of beams that form triangles

○ Trusses are often used in the roofs of home construction

projects.

○ Trusses can also be bent or curved and still retain

their strength

● Trusses take advantage of triangles to make the structure strong as

the forces are distributed between the vertices.

The Arch (Sugar Cube Arch Bridge)

● Arch – Is a curved structure often used to support loads

● Arches are used in spaces where supporting beams are not practical.

● The arch relies on the ‘keystone’ to stay upright. This is the stone

that is placed at the top of the arch.

● For example: windows, doorways, places of worship and bridges.

● The arch’s curved design transfers compression forces downward

into the structure.

○ Many arches built by the Romans over 2000 years ago are still

standing today.

The Dome

● Dome – A shell structure that looks like

the top half of a sphere or an egg.

● Similar to an arch, a dome directs

compression forces downward.

● In an arch, the downward force only

happens in one plane of application. In a

dome, the compression force is directed

downward in many places at once.

Geodesic Dome

● A hemispheric thin shell structure

based on a geodesic polyhedron.

● Similar to an arch, a dome directs

compression forces downward.

● The triangular elements of the dome are

structurally ridgid and distribute the

structural stress throughout the structure,

making the geodesic comes able to

withstand heavy loads.

Lesson 5: Structural Failure

Big Ideas:

● Structures have a purpose

● The form of a structure is dependent on its function

● The interaction between structures and forces is predictable

Textbook Links:

Chapter 11 Textbook

- Focus on

- 11.6 - Structural Failure

What is Structural Failure?

Structural Failure is the failure of any structure as the result of the

structure, or part of the structure, losing the ability to support a load.

Once the structure loses its load-carrying ability, it cracks, deforms, or

even collapses completely. There are many reasons why a structure can

fail.

Reasons For Structural Failure

There are four possible causes for structural failure:

● Bad Design

● Faulty Construction

● Extraordinary Loads

● Foundation Failure

Bad Design

Approximately 40% to 60% of all structural failures are due to bad design.

Bad designs can be caused by design errors such as failure to account for

load, specifying incorrect materials, or not considering important factors

and stresses.

On January 28, 1986, just 73 seconds after takeoff, the space shuttle

Challenger exploded (Figure 3).

The explosion was caused by a gas leak when an O-ring failed. An O-ring

is a circular piece of plastic or rubber that stops water or gases from

escaping. An O-ring is usually in a connection between two pipes (Figure

4). In the case of the Challenger, the weather in Florida was unusually cold.

The cold O-ring failed and caused the gas leak, leading to the explosion.

CNN’s coverage of the Challenger explosion

Faulty Construction

Faulty construction is the second most common cause of structural failure.

Construction errors can result from using poor quality materials, poor

installation from either sloppiness or lack of expertise, or a combination of

these. For example, homeowners know how easily shingles are blown off a

roof in windy conditions. This is a bigger problem if the shingles were

poorly installed by not securing them correctly with the right type of nail

(Figures 6 and 7). Using the wrong nail for the job can mean the difference

between a roof that lasts for 20 years and one that fails on the first windy

day.

Extraordinary Loads

Extreme conditions can also result in

structural failure. Often, these failures

are not the result of poor design, but

the result of unexpected events that

create extraordinary loads on

structures. In January 1998, North

America experienced a massive ice

storm.

For days, parts of Ontario, Québec, Nova Scotia, New York, and Maine

were drenched with freezing rain. The rain coated everything with a 120

mm–thick layer of ice.

About 130 transmission towers were crushed under the weight of the ice.

1998 Ice Storm Coverage

Foundation Failure

Failure of a structure’s base, or foundation, is less common than bad

design and faulty construction. However, it can also

lead to significant structural problems. Foundation

failure can be caused by poor soil conditions, poor

installation, a foundation that is not large enough for

the load of the structure, or earthquakes. A

well-known example of foundation failure is the

Leaning Tower of Pisa in Italy.

The tower was built in 1178 on sandy, unstable soil

with an inadequate foundation. The soil shifted and

the tower began to lean almost right after

construction began. Over the centuries, the tower

leaned more and more. Modern construction

methods have finally slowed down the movement

of the tower and returned it to the angle at which it was leaning in 1870.

Case Study

In 1879 the Tay Bridge in Scotland failed during a violent storm, when the

middle of the bridge collapsed. A report found that the columns used to

hold the bridge up had broken at the bottom. The winds from the storm may

have caused the train travelling across the bridge to sway into the walls of

the bridge itself. It was also found that other bridges designed by the same

architect were designed in such a way that they might collapse in the

future.

Using the information above, identify one possible type of structural failure

responsible for the collapse of the Tay Bridge. Explain why this may have

caused the collapse, using key vocabulary from the unit.