Frame Structures - recursostecno

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29 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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Structures

Hold, protect & provide shape

Manuel Ángel

Martínez García (manuelmg@educastur.princast.es)

Jesús Prieto Fuentes (jesuspf@educastur.princast.es)

Víctor Manuel

Sánchez Canga (victorsc@educastur.princast.es)

Grupo de trabajo PALE 2008


Área de Tecnología

Unit Layout (9 lessons)


Structures (Technology
-

2
nd

Year of ESO)


What are structures? Examples in Asturias.


Different types of structures


Frame, Shell, Solid (or mass).


Types of forces acting on structures


Compression, Tension, Bending, Torsion & Shearing.


Structural elements


Beams, columns, joists, foundations, steel sections,
arches, ...


Joints


Rivets, welding,
nuts
& bolts, hinges, ...


Projects


3 projects ...


Summary


Aims and objectives


Aims


To

raise

students’

awareness

of

the

role

played

by

structures

in

common

objects
.


To

show

how

structures

work

and

how

we

can

use

them

in

our

projects
.


Objectives

At

the

end

of

the

unit,



Most

of

the

students

should

be

able

to

identify

different

types

of

structure

and

explain

their

use
.


Most

of

the

students

should

be

able

to

analyze

simple

structures

and

forces
.


Some

of

the

students

should

be

able

to

design

simple

structures

with

certain

constraints
.

Vocabulary

Beam.

Joist &

Breeze Block

Steel Sections (T, I, …).

Columns

Rivets

Welding


Nuts & Bolts


Hinges


What are structures?


Everything

has

a

structure
.

A structure is something that

1.
Protects.

2.
Provides shape.

3.
Supports loads.

What are these structures for?

Functions

1.
Protects.

2.
Provides shape.

3.
Supports loads.

3

1,2,3

1,2

Structures in Asturias I

Coal washing plant

Saints Bridge (Asturias
-

Galicia)

Fernández Casado Bridge (Asturias
-

León)

Cangas de Onís Bridge

Structures in Asturias II

Coal mine shaft

Grandas de Salime
dam

Negrón Tunnel (Asturias
-

León)

Steel Factory
cooling tower

Structures in Asturias III

Oviedo
Cathedral

Church in
Universidad
Laboral

Viaduct,

Luarca

Oviedo
Congress
Centre
(Calatrava)

Types of structures I

Mass

Structures


Solid

structures

which

rely

on

their

own

weight

to

resist

loads
.

Examples
:

a

brick,

a

dam
.

Shell

structures


Made

or

assembled

to

make

one

piece,

usually

thin

sheet

material

with

ridges

or

curves

to

make

it

stronger
.

Examples
:

Tin

cans,

bottles,

car

and

airplane

bodies,



Types of structures II

Frame

Structures


These

are

made

from

many

small

parts

(called

members)

joined

together
.

Bridges,

cranes

and

parts

of

an

oil

rig

are

a

few

examples
.


Structures

can

also

be

classified

as


Natural Structures

Made by natural means

Manufactured

Structures

Man
-
Made

Loads I

Loads can be either static or dynamic.

Static Loads

Those which remain constant.
Example: the weight of the
materials from which a structure
is made.

Dynamic Loads

Those which exert constantly
changing forces upon a structure.
Example: a car crossing a bridge.

Loads II

Loads produce the following effects.

Bodies with Elastic Behaviour (elasticity)

They change their shape, but return to their original form when the
load is removed. Most materials exhibit elastic behaviour to some
extent. For example: gently bend a plastic ruler.

Bodies with Plastic Behaviour (plasticity)

They change their shape, but they don’t return to their original form when
the load is removed. For example: bend a paper clip. Up to a certain point, a
paper clip will spring back into shape. If you bend it too far, it springs back
slightly but stays permanently bent. This means it has been bent beyond its
elastic limit.

Loads III

Bodies with Rigid Behaviour (rigidity)

They don’t change their shape when a load is applied. If the load is
too heavy, they just break.

REMEMBER

1.
Structures

should

operate

within

the

elastic

limit

of

their

materials
.


2.
Structures

shouldn’t

break

under

the

weight

of

loads
.


3.
Structures

shouldn’t

change

their

shape

significantly

under

the

weight

of

loads
.

Example: If you try to bend a piece of glass,
you can’t. If you increase the force beyond a
certain limit, the glass just breaks.
It is
said that glass is rigid
.

Loads IV

Types

of

Loads



Loads

are

produced

by

forces
.

Depending

on

these

forces,

the

following

effects

can

be

caused
:

Compression
-

for example, the buckling of a bridge pier.


Tension

-

for example, the stretching of a suspension bridge chain or
strut


Bending
-

compression and extension combined, for example, with a
bridge beam.

Loads V

Torsional

or twisting of a bar or a key in the lock

Shear
,for example, a bridge beam, a metal shear or a cutting pliers


Loads VI

Compression

Bending

Example

Structural analysis


D整敲浩湥 瑨攠瑹灥 潦o汯l搠慦晥捴楮朠敡捨e
灩散p 潦⁡⁳o牵捴畲e


Load

Idea


䥭慧I湥n愠灩散攠潦⁴桥h獴牵捴畲攠扲b慫a
.
What happens to
the pieces?

Load

Load

Tension

Compression

Loads VII

Stability (I)

Structures

should

be

stable



They

should

support

external

l
oads

without

falling

down,

falling

over

or

collapsing
.

Unstable building

Unstable slope

Stability (II)

We

can

gain

stability

in

our

structures

by
:

a)

Choosing

an

adequate

shape


flat

and

wide

shapes

are

the

most

stable
.


b) Lowering the centre of mass

Stability (III)

c)

Anchoring

the

structure

to

the

floor



Using

wires
.

d)

Sticking

the

structure

into

the

floor



Deep

foundations

Structural Elements I

Arches

They stop the downward bend of a flat beam. The forces in an arch are
transferred to the foundations at the base of the arch. The weight is
carried down along two curving paths.

How can we build strong structures?

By using resistant structural elements made of light, resistant
materials.

Beams

These are horizontal elements designed to support bending, produced
by vertical forces.

Structural Elements II

Joists



These

are

the

horizontal

supporting

members

that

run

from

wall

to

wall,

wall

to

beam,

or

beam

to

beam,

to

support

a

ceiling
,

a

roof

or

a

floor
.

They

are

made

of

wood
,

steel

or

concrete
.



They

are

often

supported

by

beams

and

are

usually

repeated
.



B
eam
s

are

bigger

than

joists
.

Joist

Beam

Hollow concrete blocks
or breeze blocks, to fill
gaps between joists

Structural Elements III

Columns

These are vertical elements designed to support horizontal loads
and transmit the forces to the ground.

Foundation elements

These are elements designed to reinforce the ground so it can bear the
vertical forces produced by the whole structure built upon it. For example
footing elements
.

N.B.

Foundations prevent the soil collapsing under the
weight of the structure. The weaker the soil, the
stronger (and more expensive) the foundations.

Structural Elements IV

Profiles

Resistance of structural elements depend on:



The materials used to build the elements.



The shape of the elements. Some shapes (profiles) are stronger
than others.

I shaped steel profile

L shaped steel profile

U shaped steel profile

Steel tube

Structural Elements V

Triangles






Very useful for structures

Application

Is it possible to build a structure that supports a book with a piece
of card?

Structural Elements VI

Solution

Folding the piece of card


forming arcs and triangles.


Evaluation


Learning:


Activities


Exam


Teaching: Pass rate of students


Less than 60%


Unsatisfactory


From 60%
-
70%


Poor


From 71%
-
80%


Acceptable


From 81%
-
90%


Good


More than 91%


Very good


Questions are welcome

Plenary

Bibliography & acknowledgements

In this work we have use pictures and taken information from the following
sources:

The Internet, specially these sites


http://en.wikibooks.org/wiki/SA_NC_Saaste_Tech:Modules_Structures_grade_5


http://www.chester.ac.uk/~mwillard/sci_ed/structures/structures.htm


http://www.edselect.com/grade51.htm


http://www.deyes.sefton.sch.uk/Technology/Keystage3/structures.htm#WHAT%20I
S%20A%20STRUCTURE
?


“Design & Technology”, by James Garratt (ISBN0
-
521
-
55607
-
4)