STRUCTURES TECHNOLOGY, PROGRAMMING AND ROBOTICS

WHAT ARE WE GOING TO LEARN?

Recognise the different structures and why they are necessary

Understand how forces act on a body and how they affect it

Distinguish types of structural elements and learn when to use them

Explain the different Conditions of a structure and analyse their functions

Identify types of stress that act on each element in a structure

Design and build a structure for a specific purpose

WHY ARE STRUCTURES IMPORTANT?

A bad structure can damage things or people

They keep things in their place. They keep things safe.

https://www.youtube.com/watch?v=ft2uIYucsXo

https://www.youtube.com/watch?v=3mclp9QmCGs

https://www.youtube.com/watch?v=knaNXcKS-qM

WHY ARE STRUCTURES IMPORTANT?

WHAT IS A STRUCTURE

Structure is the set of elements in an body (could be small, big, huge…) that are made to resist the effects of the forces that are trying to break or deform it

WHAT IS A STRUCTURE

All physical bodies have a structure:

Humans and vertebrate animals have bones

A building has beams and columns

WHAT IS A STRUCTURE

Structures can be:

Man-made

Natural: bones, shells of the crabs…

FORCE AND LOAD

FORCE: Is a measure of the interaction between bodies. It takes a

number of forms including electromagnetic, and gravitational forces.

Static effect: When you apply a force in a body to deform or break it but you

don’t move it

Dynamic effect: when you make the object move or stop moving

FORCE AND LOAD

LOAD: Is a term frequently used in engineering to mean the force

exerted on a surface or body.

Fixed loads: don’t vary over time (weigh of the rooftop)

Variable loads (snow, wind, …)

FORCE AND LOAD

Forces can be applied in a different way each time (point of application,

direction or trajectory).

Look at the picture of the bottle in page number 7

TYPE OF STRESS

Loads produce stress on the structure of a body.

Stress is the internal tension that the bodies experience when one or

more forces are applied to them

All bodies are deformed in some way, but for those made with elastic

materials, it’s more obvious

TYPE OF STRESS: TRACTION

When forces try to stretch the body they act on.

Opposing forces

Same direction

Different trajectory

Examples:

Cables of the suspension bridge

Chords of the guitar

Rubber band

TYPE OF STRESS: COMPRESSION

When forces try to compress the body they act on.

Opposing forces

Same trajectory (inwards the object)

Examples:

legs of a chair

columns

TYPE OF STRESS: BENDING

When forces try to bend the body they act on

Examples:

Bar in a wardrobe

Deck of a bridge

TYPE OF STRESS: TORSION

When forces try to twist the body they act on

Examples:

Mop

Kitchen cloth

TYPE OF STRESS: SHEARING

When forces try to divide the body they act on

Examples:

Scissors on a paper

TYPE OF STRESS

Traction: Stretch a body

Compression: compress a body

Bending: bend a body

Torsion: Twist a body

Shearing: Cut or divide a body

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Massive structures and lintels: carved from rock and built by stacking rocks or other

materials.

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Vaulted structures: formed by arches and vaults using stones that the only stress they

support is compression. They cover larger spaces and have bigger gaps in the structure

*Vault = bóveda

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Triangular structures: bars made of metal or wooden. Ideal for making bridges. TRUSS

Triangles vs. squares

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Suspended structures: They use cables, called suspenders. The cables support only traction

stress. They can cover large spaces

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

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Reinforced concrete structures: Concrete could be made into any shape, so it led to great

advances in engineering. It is a very strong material. They are used in every building.

Concrete does NOT resist traction

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Laminated structures: Laminates of metal or other material, forming a strong shape. Used in

modern architecture.

MAN-MADE STRUCTURES

Chronologically, we have seen different structures throughout our history:

Pneumatic structures: light and easy to transport. It is normally used in events.

5. STRUCTURAL CONDITIONS

If we want a structure to work well…:

Stability: The capacity of a structure to remain standing. Centre of gravity must

be centred over its base and close to the ground.

Resistance: The capacity of a structure to bear the tensions without breaking.

Rigidity: Capacity of deformation.

STRUCTURAL ELEMENTS

Vertical elements:

Pillars: round or rectangular

Columns: often has a decorative function as well.

STRUCTURAL ELEMENTS

Horizontal elements:

Beams: sits of pillars and transfer the weight.

Joists: Small beams.

Lintels: use to create open spaces between columns

STRUCTURAL ELEMENTS

Arches and vaults:

Arches: use a key Stone and a centring.

Vaults: series of arches in a line.