Unit 3. Structures: Technology & Digitisation for Middle School

UNIT 3. STRUCTURES

FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

INDEX

1. WHAT'S A STRUCTURE?
2. FORCES, LOADS AND EFFORTS
3. TYPES OF FORCES
4. CONDITIONS OF STRUCTURES
5. THE EVOLUTION OF STRUCTURES IN BUILDINGS

FINAL ACTIVITIES PROJECT 3: A TRUSS OF RECYCLED PAPER UNIT 3 STRUCTURES FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION I1. What's a structure?fec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

LET'S SPEAK

What would happen if we didn't have a skeleton? Why do paper cups have a ring on their upper part What happen when we kick a ball? Is the same effect if the ball has no air in it? FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

1. WHAT'S A STRUCTURE?

A STRUCTURE is a set of elements of an object or body that support external actions so that the object or body doesn't deform or break You must know that: · All physical bodies or objects have a structure. . The structure is the responsible of maintaining the shape of the object and not to bend or break when a force acts on it. · Structures can be a part of the object (in buildings) or the whole object itself (a table) More info in page 30 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

1.1 Natural and human-made structures

We can classify structures into: NATURAL . They aren't made by people. They can be: . In living things (shells, skeletons ... ) · In their constructions (nests) . The result of geological process (caves) HUMAN-MADE · They are made by people. Some examples can be: · A bridge · The chassis of a car · The frame of a bicycle · The case of a camera D More info in page 30 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION I2. Forces, loads and effortsfec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

2. FORCES, LOADS AND EFFORTS

When talking about structures we distinguish among three concepts: forces, loads, and efforts: A FORCE is anything that can deform a body (static effect) or make it move or stop (dynamic effect) line of action magnitude point of application direction (outwards) The elements that define a force are: · Point of application · Intensity or magnitude (we measure it with a physic unit called Newtons) · Line of action · Direction More info in page 61 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

2.1. Loads

A LOAD is a force that acts on a specific structure There are two types of loads: FIXED OR PERMANENT · They don't change over time, · The weight of the structure itself · The weight of the component parts VARIABLE / DINAMIC · They change over time · The weight of the traffic . The force of the wind More info in page 61 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Iweight of the truck FAST DELIVERY * Virtual ELEMENTARY SCHOOLfec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

2.2. Efforts

An EFFORT is the internal force that an object experience when a force is applied on it Depending on the forces applied, the geometry of the object or the properties of the materials, the efforts will be different in any case More info in page 61 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

ACTIVITIES

Prepare the activity sheet bending it by the middle and title it as: ACTIVITY SHEET UNIT 3. STRUCTURES Name and group Complete in a DIN-A3 the following activities: Activities 1, 4 and 5 (pg. 60 and 61) • Remember that: . It is mandatory to copy the wording of the activities · Cleanliness and handwriting will be evaluated . You can discuss the solution of the activities with your partner . At the end of the unit the teacher will ask the activity sheet to be evaluated FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

ACTIVITIES

Act 1. Pg 60. Draw and explain the purpose of these structures. Are they natural or human-made? a. a skeleton. Natural. A skeleton is all the bones that support your body b. a plastic cup. Human-made. A plastic cup holds liquid and allows the user to drink from it c. a boat. Human-made. A boat is used to floating and travel on water, providing stability and holding passengers. d. a crab's shell. Natural. A crab's shell is a hard cover (exoskeleton) that protects it and supports the body. e. a bee's nest. Natural. Is the structure that bees build as a house for them and the queen and to keep food. f. a cave. Natural. Caves are formed by different geological processes and can be used as dwellings. Act 4. Pg 60. Answer the questions. a. What's the purpose of a structure? To maintain the shape and not to bend or break when a force acts on it. b. Why aren't some structures easy to distinguish? Because sometime the whole object forms the structure Act 5. Pg 61. Say if the force has a static or dynamic effect on these actions. a. Hitting a golf ball. Dynamic effect b. Pushing a shopping trolley. Dynamic effect C. Your heart pumping blood. Dynamic effect d. Sitting down on a sofa. Static effect FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION I3. Types of forcesfec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

LET'S SPEAK

CRUSH BEND STRETCH DIVIDE TWIST How do you think the marshmallow will deform in each photo? FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

3. TYPES OF FORCES

We classify the different forces that act on structures depending on they deform in: TENSION COMPRESSION BENDING TORSION SHEARING or CUTTING The forces try to STRETCH the object. The forces are opposing, in the same line of actions but in different directions away from each other Experience tension the wires of a hanging bridge or the chain of a lamp The forces try to CRUSH or The forces try to BEND the COMPRESS the object object The forces are opposing, in the same line of actions but in different directions inwards the object Experience compression the columns of a building or a person's legs Opposing forces, in separated lines of actions. Experience bending the beams of a building or the bar of a wardrobe The forces try to TWIST the object Rotational forces act in different directions Experience torsion screws or the perimeter beams of the buildings The forces try to DIVIDE the object Two forces are opposing, in line of actions next to each other and in different directions Experience shearing the beams of a building close to the columns More info in page 62-63 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION ITension Virtual ELEMENTARY SCHOOLfec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

ACTIVITIES

Act 7. Pg 63. Copy these diagrams and explain in detail what force each one is. Add some examples Act 11. Pg 63. Analyze the efforts that act on the different elements of the bridge in the photo. Imagine the different loads of the weights of the trucks that appear and think of how them deforms each part of the bridge. FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION I4. Conditions of structuresfec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

4. CONDITIONS OF STRUCTURES

There are three different conditions that every structure must have to work properly: STABILITY It must remain upright and don't fall over . The centre of gravity of the structure be close to the centre of its base and the ground RESISTANCE RIGIDITY It must be able to bear the tensions acting It must be able to bear the tensions acting on it without breaking on it without deform too much The resistance of a structure depends on its shape and on the material it has built with All the objects deform when forces act on them, but a good structure will not show that deformation. Rigidity depends also on the material and the shape of the structure More info in page 65 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

4.1 How to give a structure stability

To make a structure more stable, we can use the following methods: MAKE THE BASE WIDER BURY THE BOTTOM PART in the ground and use special foundations CENTRE THE WEIGHT AT THE BOTTOM adding even extra weight FIX THE STRUCTURE TO THE GROUND using cables to make the base wider More info in page 65 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

4.2 How to give a structure resistance

To make a structure more resistance, we can use the following methods: ADD MATERIAL TO THE STRUCTURE USE MATERIALS MORE RESISTANT USE THE IDEAL MATERIAL FOR THE EFFORT The materials in order from the most to the least resistant are: Steel, stone, cement, wood, plastic, string All the materials have a rupture strength for each type of effort More info in page 65 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

4.3 How to give a structure rigidity

To make a structure more rigid, we can use the following methods: CONSIDER THE SHAPE OF THE ELEMENTS MAKE RIGID JOINS TRIANGULATE THE ELEMENTS The type of force will determine the best structural shape. Hollow beans hold up well under compressions T and I beans are best for resisting bending The efforts in structures are bigger close to joints of the different elements. To reinforce joints, we use stiffeners or increase the surface of welding Triangulations prevent deformation in bar structures More info in page 65 FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION Ifec Hacemos escuela, educamos personas Colegio Santa Joaquina de Vedruna Madrid

ACTIVITIES

Act 14. Pg 64. Look at the diagrams on the left. Which structure do you think is more stable? Which is less stable? Why? The first structure a is the most stable structure because of its large base and because its centre of gravity is located close to the ground. a. b. c. The second structure is quite stable because its centre of gravity is inside its base, but its base is shorter than a, so any heavy enough load on the edge will cause the object to fall over. The third structure isn't stable because its centre of gravity falls outside its base, and it will fall over. Act 15. Pg 65. Copy the diagram and explain when buckling appear? Why's buckling in a structure dangerous? How can we avoid bucking? T * Buckling appears when elements that are compressed are too thin. It is dangerous because it is a problem difficult to reverse and can make a structure to collapse. Compressed elements must be wide enough to avoid buckling. FECSJV 2024/2025 | TECHNOLOGY & DIGITISATION I