Identification of Soils and Rocks

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25 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Reinforced Concrete

I. Operation of Rational Numbers


Addition: 5 + 3 = 8 (The equation expressed in
English is five plus three equals eight, in which 5
is defined as addend, 3 as addend or augend, and
8 as sum or total.


Subtraction: 7


3 = 4 (The equation expressed in
English is seven minus three makes four, in
which 7 is defined as minuend, 3 as subtrahend,
and 4 as remainder or difference.)


Multiplication: 3 x 4 = 12 (The equation
expressed in English can be three times /by/
multiplied by four makes twelve, in which 3 is
defined as multiplicand, 4 as multiplier, and 12
as product.)


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Monday, November 25, 2013

Reinforced Concrete

I. Operation of Rational Numbers

4.
Division:

1)
8
÷

4 = 2 (The equation expressed in English can be
eight divided by four makes two, in which 8 is defined as
dividend, 4 as divisor, and 2 as quotient.)

2)
9
÷

4 = 2 … 1: (The equation expressed in English can
be nine divided by four makes two and one over, in
which 9 can be called partial dividend and 1 as
remainder.)

4.
Power


3
2

= 3 x 3 = 9 Three squared equals three times three
equals nine.


2
3

= 2 x 2 x 2 = 8 Two cubed equals two times two times
two equals eight.


2
4

= 2 x 2 x 2 x 2 = 16 The fourth power of two equals
two times two times two times two equals sixteen.


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Monday, November 25, 2013

Reinforced Concrete

I.


Disadvantages of plain concrete


Weak in tensile strength

II.
*The disability of plain concrete is overcome in two
ways:
reinforced concrete
(RC) and prestressed
concrete (PC).

1.
Reinforced concrete is plain
concrete

in which
steel

rods or bars ("
rebars
") have been incorporated to
reinforce the naturally brittle concrete.

III. *Function of Steel and concrete in RC

1.
Steel takes up a small quantity but a major part of
the cost (the cost of the formwork, the cost of the
concrete and the cost of the steel are approximately
the same)

2.
Concrete takes the compression, steel takes the
tension.

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Monday, November 25, 2013

Reinforced Concrete

III.
Function of Steel and concrete in RC

3.
Steel is the vital part of the structure due to the
deficient tensile strength of concrete;

4.
The coverage of concrete prevents steels from
rapid rusting;

5.
The proper adhesion between the steel and the
concrete is of the greatest importance, and bars
should be of a sufficiently small diameter;

6.
The bars should be limited so that they do not
obstruct the proper placing the concrete and so as
to provide adequate space for the reinforcement
to develop the stress by transmission from the
concrete;

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Monday, November 25, 2013

Reinforced Concrete

7.
Individual reinforcing bars generally do not
exceed 12 m (39ft) in length.

IV. *Advantages of RC

1.
Advantages of concrete: low cost, good weather
and fire resistance, good compressive strength,
excellent workability/formability

2.
Advantages of steel: high tensile strength, greater
ductility, toughness

3.
Advantages of combination of steel and concrete

1)
Relatively low cost

2)
Good weather and fire resistance

3)
Good compressive strength

4)
Excellent formability

5)
Considerably high tensile strength


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Monday, November 25, 2013

Reinforced Concrete

V. *Disadvantages of RC

1.
Cracking is inevitable which is induced by the
mere process of the reinforcing steel being
stressed under the normal working loads

2.
The higher steel stress increases the strain of the
concrete

3.
Stress v.s. Strain

1)
stress: the force per unit area

2)
Strain: the elongation per unit length

VI.
Homework



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Monday, November 25, 2013