Unit D: Structures and Forces

SECTION 1.0 - STRUCTURES ARE FOUND IN NATURAL AND HUMAN-MADE ENVIRONMENTS.

1.1 Classifying Structural Forms

Structures can be categorized as ________________ or ________________ (manufactured)

There are three basic structural forms:________________ Structures: usually stronger than either ________________ or ________________ structures

Frame Structures: the ________________ of the frame comes from how the parts are ________________, ________________ than solid structures

When more than one type of structure is used, it is called a ________________ structure

Shell Structures: round outer surfaces usually ________________ than flat ones because the load is distributed more ________________

Natural Frame Manufactured Frame

Natural Solid Manufactured Solid

Natural Shell Manufactured Shell

Combination Structures

These structures use the ________________ of all three basic forms to their ________________ so we can create ________________ structures.

Most buildings and complex structures are ________________ structures.

Assignment Check and Reflect p.268 #1, 3, 4

1.2 THE FUNCTION OF STRUCTURES

________________ structure has at least one ________________ to perform (even if it’s just to represent something ________________ or thought provoking, such as a statue), and some have ________________ functions.

Balancing structural ________________ with effective ________________ is always a technological challenge.

Function of a structure – its ________________ When a structure has multiple ________________, it also has multiple _____________

Structures may look different but serve as a ________________ function (ie. Different types of roofs; you must take into account the ________________, living conditions, and the ________________ of the people ________________ under them)

________________ refers to the ________________ appearance or effect that an object has because of its ________________.

Assignment Check and Reflect p.275 #1, 2ab, 4

1.3 HUMAN-BUILT STRUCTURES AROUND THE WORLD

The designs of structures with ________________ functions around the world have been influenced by ________________, culture, tradition, ________________, and economics.

The human home is a good example.All homes provide ________________All homes are basically ________________

Assignment Check and Reflect p.278 #1

SECTION 2.0 EXTERNAL AND INTERNAL FORCES ACT ON STRUCTURES.

2.1 MEASURING FORCES

A ________________ is commonly defined as a ________________ or a ________________ on an object.

They can cause ________________ or they can be applied to objects at ________________.

When examining a force, three points must be considered: the magnitude (or size) of the force; the direction of the force; and the location where the force is applied.

The ________________ of a force refers to the ________________ of force being applied. It is measured in a unit called a ________________.

One Newton (N) is about the force exerted on your hand by an apple(100g). Holding a 1kg (1000g) book would take 10N

The ________________ of a force identifies where the force is being ________________.

The ________________ indicates at what ________________ on the structure a force is applied.

The magnitude, direction, and location of a force can be shown on a diagram by an ________________. The direction and location in which the force is acting is shown by pointing the head of the arrow in the ________________ of the force. Sometimes arrows are drawn at a range of ________________ to indicate the magnitude of the force.

Assignment Check and Reflect p.284 #1, 3

2.2 EXTERNAL FORCES ACTING ON STRUCTURES

Every object has a ________________ and ________________.

The Mass is a measure of the ________________ of matter in an object. Mass is measured in ________________.

The weight of an object is a measure of the force of ________________ on an object. Weight is measured in ________________.

All objects have a ___________________________. The centre of gravity is a point from which an object can be suspended in any ________________ without tending to ________________, or fall _______________________.

Many structures are designed to carry a ________________.

A static load refers to a weight that does __________________________. A static load can also refer to the ________________ of the structure itself. A dynamic load refers to any external force that ___________or ________________.

Beam bridge: most common bridge, a ___________beam and support _____________at each end.

Truss bridge: ________________ and strong, ________________ frames along its sides.

Arch bridge: designed to withstand ________________ loads, load is transferred from centre of arch to the ground which ________________ (resists) ________________ the arch.

Suspension bridge: ________________ support main cables which are ________________ in the ground, smaller ________________ that support the bridge deck hang from the main cables.

Where a ________________ span must be crossed, usually a ________________ bridge would be built ________________ than a beam, truss, or arch bridge.

When a ________________ (or any other structure) is built, it is usually expected that it will meet set ________________ requirements.

Performance requirements- shows that the structure when in ________________ performs to certain ________________

Assignment Check and Reflect p. 295 #1, 2, 3, 4a

2.3 INTERNAL FORCES WITHIN STRUCTURES

________________ forces acting on a structure put the structure under ________________.

A ________________ on a structure creates ________________.

An objects compressive strength is its ability to ________________ a compression force without ________________ its shape or ________________.

A ________________ on a structure creates ________________.

An objects ________________ strength is its ability to ________________ tension before breaking.

Applying __________forces at different spots in different ________________ to a structure creates _____________.

When a structure _____________, the upper side of the structure ________________ under the tension and at the same time the underside of the structure becomes ________________, these are ____________________forces.

Assignment Check and Reflect p. 299 #1, 2

2.4 DESIGNING STRUCTURES TO RESIST FORCES AND MAINTAIN STABILITY

One of the challenges in building a structure is to ensure it is able to ________________ all forces exerted on it.

In determining the structure’s ability to ________________ the forces acting on it, the choice and arrangement of components used to build the structure are ________________.

A ________________ is the strongest shape

Basic structural components:

An ________________: force of the load is carried through to the arches foundation, ________________ is distributed ________________.

A ________________: a flat structure supported on ________________. A ________________ is a framework of ______________. (How carpenters build roofs

on houses) A ________________: a beam that is only supported at __________ end. (like a diving

board) A ________________: a solid structure that can stand by itself. (________________)

Columns, crossbeams

Cantilever arches, columns, crossbeams, triangles, truss bridge

arches, arch bridge, columns, crossbeams

columns, crossbeams, arches, truss’

A combination of ________________ and ________________ forces on a structure can weaken it causing structural ________________.

When a ________________ change occurs in a structure caused by abnormal internal forces the result is structural ________________.

Structural ________________ occurs when a structure can no longer stand up to the ________________ acting on it.

A structure needs ________________ and ________________ to avoid failure The ________________ of the materials used in the components of a structure and its

design affect structural ________________.

Assignment Check and Reflect p. 306 #1ab, 2 Assess your learning p. 307 # 4

SECTION 3.0 STRUCTURAL STRENGTH AND STABILITY DEPEND ON THE PROPERTIES OF DIFFERENT MATERIALS AND HOW THEY ARE JOINED TOGETHER.

3.1 MATERIALS AND THEIR PROPERTIES

The materials used in structures can be ________________ according to their ______________.

________________ occurs when a structure or structural component changes ________________ due to the forces acting on it.

A structure or structural component is ________________ when it can ________________ under load without breaking.

Deformation is more likely to cause a structure to ________________ than ________________ is. Flexibility helps ________________ the structure from deforming and breaking.

The strength of a ________________ is different from the strength of the ________________ in the structure.

Commercial properties can influence the ________________ of ________________ properties a product has.

________________________used in buildings usually have one or more properties that make them unique and functional for the structure under ________________ and development.

Assignment Check and Reflect p.312 #1, 2

3.2 JOINING STRUCTURAL COMPONENTS

The purpose of a ___________ is to _______________ the components of a structure together.

A common method of ________________ two materials is to ________________ and ________________ them. (This type of joint is called a “________________ joint.”)

A joint in a structure should be designed so that it uses the ________________ amount of material and holds the ________________ load.

________________ considerations such as weight, cost, and appearance must also be taken into account.

The ____________________of a joint can be compromised by how it is constructed.

________________ use of materials to build or connect the joint can cause the joint to fail________________

A joint can be either ________________ or ________________.

A fixed joint is ________________ to prevent the movement of components. A movable joint is ________________ to allow a component to move.

Some joints rely on the force of friction.E.g. nails, screws, and staples

Other joints rely on two surfaces bonding together.E.g. gluing, taping, welding

As the ________________ changes, the force of ________________ increases.

________________ is the result of the ________________ of the object (mass and gravity), and the type of materials interacting.

Assignment Check and Reflect p.318 #3

3.3 PROPERTIES OF MATERIALS IN PLANT AND ANIMAL STRUCTURES

Each of the components of the human ________________ is a unique material with special properties suited to the ________________ of that part.

________________ are hard and rigid. They ________________ and protect other parts of the body.

________________ reduces ________________ and provides a smooth surface for movement and absorbs shock.

________________ are bands of strong connective tissue that ________________ some bones together.

________________ are fibrous tissues that allow bones to move by ________________ and relaxing.

________________ are strong and flexible tissues that ________________ muscles to bones.

Joints

ball and socket: hips and shouldershinge: elbows and kneespivot: spinal columngliding: wrists

________________ provides structural shelter by waterproofing the body and protecting it from bacteria. Skin also regulates body ______________________.

Human Skeleton

Human Joints

Assignment Check and Reflect p.321 #2

SECTION 4.0

STRUCTURES ARE DESIGNED, EVALUATED, AND IMPROVED IN ORDER TO MEET HUMAN NEEDS.

4.1 BUILDING SAFE STRUCTURES IN ALL ENVIRONMENTS

A margin of safety refers to the ________________ within which a structure’s ________________ performance is considered to be ________________.

The forces used in testing the safety of a structure are ________________ than the forces the structure would have to withstand in ________________ use.

Testing for safety occurs at ________________ of a structure’s development.

________________ is also evaluated after a structure is put in use by surveying or monitoring how often a structure ___________and why.

Environmental factors can also affect a structure’s ________________.

In many parts of the world structures must withstand a variety of ________________ conditions such severe ____________, wind, rain, ____________, and ______________.

In Canada’s North ________________ is a challenge as some upper layers melt in summer making the ground soft

The terrain that a structure is built can affect its ________________. Soil stability, steep terrain, and building in low lying areas require special techniques.

Where there is risk of earthquakes structures must be designed to withstand the ________________ and ________________ forces that may act on them.

Assignment Check and Reflect p.327 #1 & 2

4.2 STRENGTHENING MATERIALS TO IMPROVE FUNCTION AND SAFETY

To counter the effect of forces acting on the structures, the strength of some materials can be ________________ by making them ________________, but this solution has its limitations.

Another way of strengthening flat components is to put a series of ___________into the material. This is called ________________, and a good example of this is corrugated cardboard.

Through ________________ and bonding, ________________ also increases a material’s strength.

Ties and ______________offer a way to strengthen the way existing components are arranged.

One method of _____________________ a beam is to make it out of a crosslink of fused ______________. Many synthetic wood beams are made this way.

The human body will fuse ___________together to achieve increased ________________ in the body.

After a bone breaks, it will heal by ______________ the two broken pieces ________________. In some situations, the fused bone will be ________________ than the original bone.

Assignment Check and Reflect p.332 #1

4.3 EVALUATING DESIGNS FROM AN OVERALL PERSPECTIVE

When structures and products are ________________, many different perspectives must be considered.

__________, ________________, ______________, and impact on the ________________ are factors that must be addressed during the object’s development.

Neglecting to consider even one of these factors could lead to the ________________ of the structure or product.

Assignment UNIT REVIEW p. 342 -345

1-18 , 21, 24, 26 , 39

Due on Exam Date