Structures

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2º ESO

TECHNOLOGY TECHNOLOGY IES Río Cabe

Covadonga Covadonga Yugueros Yugueros Valbuena Valbuena


Mechanical Mechanical forces forces There There are are many many different different forces forces in in nature nature

Gravity Gravity wind wind

If If we we push push our our pencil, pencil, this this force force causes causes the the pencil pencil to to move move If If you you press press down down on on the the rubber rubber with with your your finger, finger, then then its its shape shape changes changes

Force Force Anything Anything that that can can

deform deform aa body body Static Static effect effect

or

change change its its state state of of movement movement or or rest rest Dynamic Dynamic effect effect


structure group of of elements elements arranged arranged in in the the optimum optimum way way to to structure isis aa group

support support aa body body or or an an object object or or to to resist resist the the effect effect of of forces forces on on the the body body or or object, object, allowing allowing the the body body to to maintain maintain its its shape shape Estructura: Estructura: grupo grupo de de elementos elementos soportar soportar un un cuerpo cuerpo oo para para resistir resistir permitiendole permitiendole mantener mantener su su forma forma

dispuestos dispuestos en en la la manera manera 贸ptima 贸ptima para para el el efecto efecto de de las las fuerzas fuerzas en en el el cuerpo, cuerpo,

The The forces forces that that act act on on aa structure structure are are called called

Load Load Cargas Cargas


All All structures structures satisfy satisfy at at least least one one of of the the following following functions: functions:

11

Supporting Supporting the the weight weight of of the the object object without without breaking breaking Soportar Soportar el el peso peso del del objeto, objeto, sin sin romperse romperse

22

To To contain contain or or protect protect something something Contener Contener oo proteger proteger algo algo

33

To To resist resist the the action action of of external external forces forces Resistir Resistir la la acci贸n acci贸n de de fuerzas fuerzas externas externas

44

Covering Covering aa distance distance Abarcar Abarcar una una distancia distancia

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The The structure structure gives gives the the object object its its shape shape Dar Dar la la forma forma aa los los cuerpos cuerpos


Some Some structures structures fulfil fulfil all all functions functions The The structure structure gives gives the the object object its its shape shape To To contain contain or or protect protect something something

Covering Covering aa distance distance

To To resist resist the the action action of of external external forces forces

Supporting Supporting the the weight weight of of the the object object without without breaking breaking


Depending Depending on on their their nature nature

NATURE NATURE

ARTIFICIAL ARTIFICIAL


Depending Depending on on their their component component elements elements

Mass structures Mass structures Estructuras Estructuras masivas masivas

Frame Frame structures structures Estructuras Estructuras de de armaz贸n armaz贸n

Shell Shell structures structures Estructuras Estructuras laminares laminares


Mass Mass structures structures are are solid solid structures structures which which rely rely on on their their own own weight weight to to resist resist loads loads

Estructuras Estructuras s贸lidas s贸lidas que que dependen dependen de de su su propio propio peso peso para para resistir resistir cargas cargas

They They are are heavy heavy and and massive massive structures structures formed formed by by very very wide wide and and hard hard surfaces surfaces Son Son estructuras estructuras pesadas pesadas yy macizas, macizas, formadas formadas por por superficies superficies muy muy anchas anchas yy resistentes resistentes


Shell Shell structures structures are are made made of of aa thin thin outer outer layer layer of of material material around around aa volume volume Hechas Hechas de de una una capa capa externa externa delgada delgada

de de material material alrededor alrededor de de un un volumen volumen

Shell Shell structures structures consist consist of of resistant resistant sheets sheets or or panels panels that that surround surround an an object. object. Consisten Consisten en en lรกminas lรกminas oo paneles paneles resistentes resistentes que que envuelven envuelven un un objeto objeto


They They have have aa skeleton skeleton of of strong strong material material

These structures have long elements (bars, tubes...) joined to each other at the ends to form the skeleton of different objects Formada Formada por por elementos elementos alargados alargados (barras (barras oo tubos) tubos) unidos unidos en en sus sus extremos extremos para para formar formar el el esqueleto. esqueleto.


According According to to the the arrangement arrangement of of its its elements, elements, these these include: include: Truss Truss structures structures

Frame Frame structures structures

Suspended Suspended structures structures

Trianguladas Trianguladas They They are are characterized characterized by by the the binding binding of of bars bars forming forming triangles triangles

Malladas Malladas They They form form aa grid grid of of vertical vertical and and horizontal horizontal parts parts

These These structures structures are are hung hung from from cables cables

Colgadas


Stress

It It is is the the internal internal tension tension that that happens happens to to all all bodies bodies subjected subjected to to the the applying applying of of forces forces on on them them

Esfuerzo Esfuerzo:: Es Es la la tensión tensión interna interna que que experimentan experimentan los los cuerpos cuerpos al al estar estar

sometidos sometidos aa la la acción acción de de una una oo más más fuerzas fuerzas sobre sobre ellos. ellos.

AA structure structure is is subjected subjected to to the the action action of of different different forces: forces: its its weight, weight, the the air air or or water... water... These These forces forces cause cause different different types types of of stress stress that that the the structure structure should should withstand withstand to to remain remain balanced. balanced.


In In general general there there are are 55 kinds kinds of of stresses: stresses:

Traction Traction or or tension tension

Compression Compression compresion compresion

Tracci贸n Tracci贸n

Torsion Torsion

Bending Bending

Torsion Torsion

Flexion Flexion

Shear or cutting Shear or cutting Cortadura Cortadura


Traction Traction or or tension tension Tracci贸n Tracci贸n

This This stress stress is is caused caused by by forces forces acting acting on on aa body body that that tend tend to to stretch stretch it it Estirarlo Estirarlo

Pull

Examples Examples

rope rope with with aa pendant, pendant,

Pull


Compression Compression Compresi贸n Compresi贸n

This This stress stress is is caused caused by by forces forces acting acting on on aa body body that that tend tend to to flatten flatten or or compress compress it. it. Comprimirlo Comprimirlo

It It happens happens in in structures structures that that need need to to support support weights weights Push

Push

Examples Examples the the legs legs of of aa chair, chair, aa tree tree trunk... trunk...


Bending Bending

Flexi贸n Flexi贸n

This This is is caused caused by by forces forces acting acting on on an an element element that that make make it it curve curve or or bend. bend. Doblarlo Doblarlo

Examples Examples

Shelves Shelves in in aa bookcase, bookcase, beam beam


Torsion Torsion

torsión torsión

Forces Forces try try to to twist twist aa body. body. Girar Girar

Examples Examples

AA key key opening opening aa lock, lock, aa pencil pencil being being sharpened… sharpened…


Shear Shear or or cutting cutting Cortadura Cortadura

This This is is caused caused by by two two equal equal forces forces applied applied in in opposite opposite direction. direction. These These forces forces are are very very close close together, together, moving moving in in opposite opposite direction, direction, as as they they try try to to cut cut an an object object Cortar Cortar

Examples Examples

Scissors Scissors cutting cutting aa cardboard, cardboard, aa paper paper cut cut with with aa guillotine‌ guillotine‌


Column

Beam

Foundation


supports supports the the weight weight

Cimientos Cimientos

They They are are vertical vertical elements elements that that rest rest on on the the foundation foundation Columnas Columnas

They They are are subjected subjected to to compression compression

They They are are horizontal horizontal elements elements that that rely rely on on vertical vertical elements elements Viga Viga


transfers transfers the the load load to to vertical vertical elements elements Each Each of of the the parts parts of of the the arc arc is is subjected subjected to to compression compression

Tirantes Tirantes

They They are are normally normally subjected subjected to to tension tension


Conditions Conditions for for aa structure structure to to work work well: well:


The The capacity capacity of of aa structure structure to to remain remain upright upright and and not not tip tip over over capacidad capacidad de de una una estructura estructura para para

permanecer permanecer en en posici贸n posici贸n vertical vertical yy no no volcar volcar

+ stable

- stable

It It does does not not change change shape shape when when aa force force is is applied applied to to it it

No No cambia cambia de de forma forma al al aplicar aplicar una una fuerza fuerza

- rigid

+ rigid


Las Las estructuras estructuras soportan soportan esfuerzos esfuerzos sin sin romper romper



Type Type MATERIALS MATERIALS Resistance Resistance of of aa structure structure depends depends on on

Quantity Quantity

SHAPE SHAPE


SECTIONS SECTIONS

To To get get lighter lighter structures structures

If If the the elements elements have have aa certain certain shape shape or or cross-section cross-section (instead (instead of of having having aa solid solid rectangular rectangular cross cross section), section), they they can can be be just just as as strong strong but but they they are are also also lighter. lighter.


Rigidity Rigidity comes comes from: from:

Welding Welding joints joints The The appropriate appropriate shape shape Triangulation Triangulation

To To make make aa structure structure more more rigid, rigid, we we can can add add strengthening strengthening elements elements

Diagonal Diagonal bars bars

Braces Braces

Cables Cables


Triangle Triangle is is the the only only figure figure that that cannot cannot be be deformed, deformed, so so structures structures that that have have aa triangular triangular shape shape are are rigid rigid

We We can can get get aa triangular triangular shape shape by by adding adding aa diagonal diagonal bar bar


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