STRUCTURES

concretecakeUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

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STRUCTURES

1. STRENGTH AND
STRUCTURES


STRENGTH/FORCE
:

Is

all

that

can

deform

a

body

or

modify

its

state

of

movement

or

rest
.



STRUCTURE
:

is

the

group

of

elements

of

a

body

that

are

bound

to

support

the

effects

of

the

strengths

that

act

over

it
.

The

structure

keeps

the

body

from

breaking

or

deforming

in

excess
.


Structures have to be
resistant

and
stable
.


The

first

structures

were

made

of

wood,

then

man

also

used

stone
.

Nowadays

we

use

concrete

and

iron


2. EFFORTS/STRESS



If one or several strengths act over an
element of a structure, the element will
experiment an internal tension. This internal
tension is called
effort/stress
.

2.1 Different kinds of
EFFORTS/STRESS


TRACTION/TENSILE


COMPRESSION


FLEXION/BENDING


TORSION


CUT/SHEAR

TRACTION/TENSILE



THE ELEMENT OF A

STRUCTURE


STRETCHES

COMPRESSION




THE ELEMENT OF A
STRUCTURE




CRUSHES

FLEXION/BENDING





THE ELEMENT OF A
STRUCTURE
BENDS

TORSION




THE ELEMENT OF A
STRUCTURE

TWISTS

CUT/SHEAR




THE ELEMENT OF A
STRUCTURE

IS DIVIDED

IN TWO
PARTS

Efforts activities


Which efforts are applied in the following
examples?


A

B

C

D

E

F


Which efforts are applied in the following
examples?

A

B

C

Image

Structure

Effort

A

Cable

Traction

B

Shock absorber

Compression

C

Rope guide

Traction

D

E

Image

Structure

Effort

D

Column

Compression

E

Bridge

Flexion


Which efforts are applied in the following
examples?

Image

Structure

Effort

F

Nut

Torsion

G

Rivet

Shear

F

G


Which efforts are applied in the following
examples?

CHECK DIFFERENT TYPES OF EFFORTS

Image


Effort

1

2

3

4

5

6

CHECK DIFFERENT TYPES OF EFFORTS

Image


Effort

1

traction

2

flexion

3

compression

4

flexion

5

compression

6

traction

3. STRUCTURAL ELEMENTS

These

are

the

most

common

elements

that

can

be

found

in

a

structure
.



Foundations



Columns


Girders



Arches


Traction

bars

(Cables)







Foundations

are

the

base

of

any

building

and

they

are

situated

under

the

ground

and

made

of

concrete

concrete


Girders

are

horizontal

bars

that

receive

flexion

efforts




Foundation

Column

Girder

Forces



Columns

are

vertical

bars

that

receive

compression

efforts





Arch:


A semicircular

shape that joins the

gap between two

pillars.





Traction bars:

Cables or bars which

support traction efforts.


As

we

know,

a

structure

has

to

be

resistant
.









A

resistant

structure

keeps

its

shape

when

forces

are

applied
.


4. RESISTANT

STRUCTURES



The

triangle

is

the

only

geometric

shape

that

cannot

be

easily

deformed

by

applying

forces

to

any

angle
.





4.1 THE TRIANGLE






The

use

of

triangular

structures

is

very

interesting

because

they

are

very

resistant,

light

and

easy

to

construct
.


crane


pylon

Triangulation

makes

it

possible

to

transform

shapes

into

a

combination

of

triangles

and

therefore

makes

them

non
-
deformable
.


Examples

of

triangulation

are

seen

all

around

us

especially

in

the

construction

industry

(building

and

civil

engineering)
.






Some

examples

are

shown

below
.

Look

carefully

how

numerous

triangles

make

each

structure
.

Add

bars

to

these

structures

to

form

triangles

and

make

them

non
-
deformable
.

The

arch

is

another

resistant

structure

that

provides

resistance

to

structures

by

distributing

the

effort

that

structure

supports
.


4.2 THE

ARCH






5. STABLE STRUCTURES

Structures

have

to

be

stable
.






A

structure

is

stable

if

it

keeps

its

position

when

forces

are

applied
.

Stability

is

obtained

by

distributing

the

mass

evenly
.


Mass centre evenly distributed

Mass centre unevenly distributed


The

mass

centre

is

where

all

the

weight

is

concentrated


He

has

the

mass

centre

evenly

distributed


When

the

mass

is

not

evenly

distributed,

you

can

stop

the

object

from

falling

in

different

ways,

such

as

increasing

its

hold

to

the

ground
.



hold

6. TYPES OF ARTIFICIAL
STRUCTURES



Massive
:

a

great

concentration

of

material

predominates









Vaulted
:

Arches,

vaults

and

domes

are

important

holding

and

supporting

elements



arches

vaults

domes



Sub
-
frame
:

made

up

of

timber

(wood),

steel

or

concrete

intersecting

elements
.


The

structural

elements

are
:

girders,

pillars

or

columns,

and

foundations
.




Foundation

Column

Girder

Forces



Triangulated
:

Made

up

by

linking

many

triangles

forming

flat

or

spatial

networks
.



crane

oil rig

pylon



Suspended
: They are held by cables


REVISION ACTIVITIES

1

Effort

A door knob

An arch

A pen tip when you write

A screwdriver when screwing

The cable of a suspended bridge

A lintel

Scissors

the cord of a blind

Pedal axes

Girders on a bridge

Effort

A door knob

TORSION

An arch

COMPRESSION

A pen tip when you write

COMPRESSION

A screwdriver when screwing

TORSION

The cable of a suspended bridge

TRACTION

A lintel

FLEXION

Scissors

SHEAR

the cord of a blind

TRACTOIN

Pedals

TORSION

Girders on a bridge

FLEXION

2. Name the effort in each of the
following objects

A

C

B

C

D

E

3. Which of the following structures
will support efforts best? Why?

4. Which structure is more stable?

5
.

Which

of

the

following

shapes

are

non
-
deformable?

What

can

we

do

to

make

the

other

shapes

non
-
deformable?


working arm

cables

base

weight

mast

6
.

Indicate

the

efforts

that

the

following

parts

of

the

crane

are

subjected

to
.

working arm

cables

base

weight

mast

working arm

cables

base

mast

weight

FLEXION

TRACTION

COMPRESSION

COMPRESSION

TRACTION

7. Draw this bridge and indicate where
the main efforts are.

Compresion

Compresion

Flexion

Flexion