Unit 5. Structures

 What are we going to learn in this unit?  5.1 What is a structure?  5.2 Efforts.  5.3 Structural elements  5.4 Resistant structures  5.5 Stable structures  5.6 Structural Cross Sections  5.7 Artificial structures  Final activities

Rubrics Indicador Prueba Puntos

8. Define estructura y nombra estructuras naturales y artificiales E x a m e n Estructuras 2

9. Define una carga y pone ejemplos E x a m e n Estructuras 1

10. Conoce y relaciona los esfuerzos mecánicos con los efectos que producen

E x a m e n Estructuras 4

11. Identifica los esfuerzos que sufren objetos cotidianos y algunos elementos estructurales

E x a m e n Estructuras 2

12. Identifica los elementos estructurales de estructuras conocidas

E x a m e n Estructuras 1

13. Explica qué es una estructura resistente y Aplica la triangulación para mejorar su resistencia

E x a m e n Estructuras 2

14. Explica qué es una estructura estable y Aplica la diferentes recursos para mejorar su estabilidad

E x a m e n Estructuras 2

15. Reconoce la importancia de la forma de los perfiles utilizados en estructuras entramadas

E x a m e n Estructuras 2

16. Clasifica diferentes estructuras en masivas, abovedadas, entramadas, colgantes y trianguladas

trabajo estructuras

2

Unit 5. Structures

What are we going to learn today?

What is a structure?, Types and how it has changed through History

Unit 5. Structures

Which structures do you know?

5.1 What is a structure? What is a structure?

A structure is a group of elements that together are able to resist forces and to transmit them to the ground

5.1 What is a structure? Types of structure

We can find natural and artificial structures. Most of the artificial structures are based

on natural structures Natural Artificial

Exercise 5.1a 1.- Define a Structure 2.- Draw five natural structures and five

artificial structures. Natural Artificial

5.1 What is a structure?

The structures have to be resistant and stable Stable: Resistant

5.1 What is a structure?

Structures along history From very old times new materials have changed constructions.

Structure Period Material Improvement

Cabin

File Temple

Aqueduct

Cathedral

Bridge

Skycraper

Exercise 5.1 b. Make a table with these structures explaining their materiales, period, and the improvements and defects they had:

Sol Exercise 5.1 b

5.2 Efforts

What are we going to learn today?

What is an structural load? What is an effort? Types of efforts

5.2 Efforts

The structures have to resist different charges

5.2 Efforts

A load is a force applied to an object, like a truck over a bridge

5.2 Efforts

 An effort is a force that appears when a structure receives an external load

Load

Internal effort

load

Internal effort

5.2 Efforts

These are the main efforts that a structure can receive:

Traction is an effort that makes an object longer

5.2 Efforts

 Compression: is an effort that makes an object shorter

Flexion: is an effort that bends an object

5.2 Efforts

 Shear (guillotine): separates an object into two pieces

 Torsion: twists objects

Exercise 5.2a  Could you define Charge?  Why there weren’t any skyscraper

500 years ago?

5.2 Efforts   Which efforts are applied in the following

examples?

A B

C

D

E

Ejrecicio 5.2b Efforts •  Which efforts are applied in the following examples?

A B

C

Image Structure Effort

A Cable B Motorbike C Guide rope

solución

5.2 Efforts

D

E

Image Structure Effort

D Column E Bridge

• Which efforts are applied in the following examples?

5.2 Efforts

Image Structure Effort

F Nut

G Rivet

F G

• Which efforts are applied in the following examples?

Ejercicio 5.2c Efforts What effort does a column resist? What

material should we use to make the columns of a building? Why?

Exercise Nº 4 page107

solución

Ej 5.2d Efforts Keys are made with a resistant material

like steel? What effort does a key resist?

Exercise Nº 5 page107

5.2e Efforts Which efforts are applied in the

following examples? G

Image Structure Effort

A Bar/spring B Bar/spring C Spring D Spring

E Bar/spring F Bar/spring G Bar

Exercise page 107Nº 6

Solution

5.3 Structural elements

What are we going to learn next?

What elements can we find in a structure?

5.3 Structural elements

These are the most common elements that can be found in a structure

• Foundations • Columns • Girders • Arches • Cables

5.3 Structural elements

 Foundations are the base of any building and they are situated under the ground and made of concrete

concrete

5.3 Structural elements

 Girders are horizontal bars that receive flexion efforts

 Columns are vertical bars that receive compression efforts

Girder

Column

Foundation

Forces Forces

Girder

Forces

Column

Girder

Forces

Foundation

Column

Girder

Forces

Foundation

Column

Girder

Forces

5.3 Structural elements

 Arch: A semicircular shape that joins the gap between two pillars. Compresion

 Traction bars: Cables or bars which support traction efforts.

Exercise 5.3a. Estructural elements

1.- Draw the main elements of a structure showing the efforts with arrows

2.-Look around your classroom and find how many columns and girders are there.

Solution

Sol ex 5.3a. Estructural elements

1.- Draw the main elements of a structure showing the efforts with arrows

2.-Look around your classroom and find how many columns and girders are there.

Exercise

5.4 Resistant structures As we know a structure has to

be resistant.

A resistant structure keeps its shape when forces are applied.

5.4 Resistant structures What are we going to learn next?

What is a resistant structure?

Why are most structures form by triangles?

5.4 Resistant structures We have two easy ways to create resistant structures

Triangles Archs

5.4 Resistant structures Other resistant structure, the arch Arch: Provides resistance to

structures by distributing the effort of the structure.

5.4 Resistant structures

The triangle

is the only geometric shape that cannot be deformed by applying forces to any angle.

5.4 a Resistant structures

Homework make triangle with 3 tubes 5 cm long each connected with a cord.

Look to the roof of your gym and describe the structures

5.4 Resistant structures

The use of triangular structures is very interesting because they are very resistant, light and easy to construct.

crane pylon

5.4 Resistant structures

Triangulation makes it possible to transform shapes into a combination of triangles and therefore makes them

non-deformable.

Exercise 5.4a Resistant structures

1.- Indicate the name of three structures based on triangles. 2.-Add bars to these structures to form triangles and make them non-deformable

5.5 Stable structures

What are we goin to learn? How can we make it more stable?

5.5 Stable structures The structures have to be stable.

A structure is stable when it keeps its position when forces are applied.

5.5 Stable structures

Stability is obtained by distributing the mass evenly.

Mass centre evenly distributed

Mass centre unevenly distributed

5.5 Stable structures

The mass centre is where all the weight is concentrated

He has the mass centre evenly distributed

5.5 Stable structures  When the mass is not evenly distributed, you

can stop the object from falling in different ways

hold

such as increasing its hold to the ground.

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

?

?

?

? ?

?

?

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Increasing the mass distribution with two feet

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Using cables we can hold the antenna

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Placing triangles that attach the lamppost to the ground

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Lowering the gravity point.

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Increasing the weight at the base.

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

Stretching his legs, so the mass is evenly distributed

5.5 Stable Structures  How is the centre of gravity maintained in

the following situations?

A triangulated structure allows the panel to resit the force of the wind

5.6 Structural Cross Sections

What are we going to learn?

Why are some columns like a I and no solid?

5.6 Structural Cross Sections Nowadays we use non solid girders or columns,

they are called cross sections

In order to obtain more resistant and stable cross sections they have shapes adapted to their use

5.6 Structural Cross Sections They are used in constructions because they

are lighter and cheaper than the solid ones because they need less material

Solid Colum Cross Sections

5.6 Structural Cross Sections There are different shapes, and each one

has a special aplication.

Open cross sections: V. T, U, L, X and H.

Closed cross sections: O, ☐,Δ.

Exercise 5.6 Structural Cross Sections Make using paper these cross sections 5 cm

and find out which one is more resistant

5.7 Types of artificial structures

What are we going to see now?

Strucures classification

5.7 Types of artificial structures

 Massive: a great concentration of material predominates

5.7 Types of artificial structures

 Vaulted : Arches, vaults and domes are important holding and supporting elements leaving a great free space below.

Arches vaults domes

5.7 Types of artificial structures

Sub-frame: made up by timber(wood), steel or concrete intersecting elements

The structural elements of a sub-frame are the girders, pillars or columns, and foundations.

Foundation

Column

Girder

Forces

5.7 Types of artificial structures

Sub-frame: made up by timber(wood), steel or concrete intersecting elements

The structural elements of a sub-frame are the girders, pillars or columns, and foundations.

Foundation

Column

Girder

Forces

5.7 Types of artificial structures

 Triangulated: Made up by linking many triangles forming flat or spatial networks.

crane Oil rig pylon

5.7 Types of artificial structures  Suspended: They are held by cables

5.7 Types of artificial structures  Exercise: Give at least 3 examples of each type of

artificial structure

Massive Arches Sub-frame Triangulated Suspended