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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.
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