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[4] PCD > Lesson 2: Prestressed Concrete Material > Flashcards

Lesson 2: Prestressed Concrete Material Flashcards

1
Q

when a material is subjected to repeated cycles of stress or strain and its structure breaks down and ultimately leads to fracture

A

fatigue

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2
Q

when a material is subjected to a load for a very long time it may continue to deform until a sudden fracture occurs

A

creep

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3
Q

it has an endurance limit of about 0.4 times its ultimate tensile strength (UTS)

A

low-carbon steel

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4
Q

it has a higher endurance limit than low-carbon steel

A

alloy steel

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5
Q

its endurance limit can vary depending on the alloying elements and the heat treatment

A

alloy steel

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6
Q

it has a lower endurance limit than steel

A

cast iron

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7
Q

its endurance limit can vary depending on its type and the casting process

A

cast iron

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8
Q

(*) 5 factors to consider regarding fatigue resistance

A
  • type of steel reinforcement
  • stress level
  • number of load cycles
  • presence of stress concentrations
  • environment
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9
Q

(*) 4 design considerations to increase the fatigue resistance of steel

A
  • use of high-quality materials
  • design the member to minimize stress concentrations
  • avoid overloading
  • protect the member from corrosion
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10
Q
A
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10
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11
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12
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13
Q
A
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14
Q

it is the time-dependent increase in strain under
constant stress

A

creep

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14
Q

is the time-dependent decrease in stress under constant strain

A

relaxation

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15
Q

4 design considerations to minimize creep and relaxation

A
  • use high-strength steel
  • design the member to minimize stress concentrations
  • avoid overloading
  • protect the member from moisture
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15
Q

3 factors to consider in creep and relaxation

A
  • stress level
  • temperature
  • moisture content
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15
Q

2 effects of high temperature to steel

A
  • loss of strength
  • fire resistance
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16
Q

it is the effect of high temperature to steel wherein steel loses strength due to the reduction of its yield strength

A

loss of strength

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17
Q

2 effects of low temperature to steel

A
  • increased steel stress relaxation
  • increased risk delamination
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18
Q

what causes corrosion in prestressing steel?

A
  • chloride ions
  • carbonation
  • hydrogen sulfide
  • stress corrosion cracking
  • hydrogen embrittlement
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19
Q

it is the cause of corrosion in prestressing steel, which can come from a variety of sources, including seawater and deicing salts

A

chloride ions

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19
Q

it is the cause of corrosion in prestressing steel, described as the reaction of carbon dioxide with the calcium hydroxide in concrete

A

carbonation

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20
Q

it is the cause of corrosion in prestressing steel, which can come from a variety of sources, including industrial emissions, sewage treatment plants, and decaying organic matter

A

hydrogen sulfide

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21
Q

it is the cause of corrosion in prestressing steel, as prestressed steel is subjected to high levels of stress and chloride ions

A

stress corrosion cracking

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22
Q

it is the cause of corrosion in prestressing steel, as prestressed steel is subjected to high levels of hydrogen

A

hydrogen embrittlement

23
Q

3 effects of corrosion in prestressing steel

A
  • loss of strength
  • cracks in concrete
  • fracture of the steel
24
Q

the effect of corrosion in prestressing steel includes a reduction in the load-carrying capacity of the structure and an increased risk of failure

A

loss of strength

24
Q

the effect of corrosion in prestressing steel in which cracks can allow water and other corrosive agents to penetrate the concrete and further accelerate the corrosion of the steel

A

cracks in the concrete

25
Q

the effect of corrosion in prestressing steel which causes the structure to collapse

A

fracture of the steel

26
Q

it is a failure in prestressed concrete structures

A

concrete cracking

27
Q

it determines the maximum load that a structure can withstand

A

strength

28
Q

determines how much the structure will deform under load

A

modulus of elasticity

29
Q

it is the reduction in volume of concrete that occurs when it dries and hardens

A

shrinkage

30
Q

it is the increase in strain in concrete that occurs under sustained loading

A

creep

31
Q

5 factors to consider in order to reduce the amount of shrinkage and creep of the concrete

A
  • type
  • age
  • moisture content
  • temperature
  • loading conditions
32
Q

true or false:

shrinkage and creep decrease with the age of the concrete

A

false

shrinkage and creep decrease with the age of the concrete

32
Q

true or false:

concrete with a low water-to-cement ratio will shrink and creep more than concrete with a high water-to cement ratio

A

false

concrete with a high water-to-cement ratio will shrink and creep more than concrete with a low water-to cement ratio

33
Q

true or false:

concrete that is wet will shrink and creep more than concrete that is dry

A

false

concrete that is dry will shrink and creep more than concrete that is wet

34
Q

true or false:

concrete that is exposed to low temperatures will shrink and creep more than concrete that is exposed to high temperatures

A

false

concrete that is exposed to high temperatures will shrink and creep more than concrete that is exposed to low temperatures

35
Q

true or false:

concrete that is not subjected to sustained loading will shrink and creep more than concrete that is subjected to sustained loading

A

false

concrete that is subjected to sustained loading will shrink and creep more than concrete that is not subjected to sustained loading

36
Q

4 ways to reduce the amount of shrinkage and creep

A
  • using a low water-to-cement ratio
  • using admixtures
  • during the concrete properly
  • designing the structure to minimize shrinkage and creep
37
Q

3 methods used to predict shrinkage and creep

A
  • theoretical models
  • empirical models
  • hybrid models
38
Q

this method to predict shrinkage and creep are based on the understanding of the physical mechanisms of shrinkage and creep

A

theoretical models

39
Q

this method to predict shrinkage and creep are based on empirical data

A

empirical models

40
Q

this method to predict shrinkage and creep combines theoretical and empirical approaches

A

hybrid models

41
Q

3 movements in concrete structures

A
  • expansion
  • shear
  • bending
42
Q

this movement in concrete structure occurs when concrete is heated; in contrast as concrete contracts when it is cooled

A

expansion

43
Q

temperature changes can cause movements in concrete structures, potentially leading to shear stresses

A

shear

44
Q

temperature changes can cause movements in concrete structures, potentially leading to bending moments

A

bending

45
Q

4 ways to reduce the amount of movements in concrete structures

A
  • using a concrete with a low coefficient of thermal expansion
  • using a thermal break
  • designing the structure to minimize thermal stresses
  • using a control joint
46
Q

it is the ability of a material to resist weathering or other destructive influences

A

durability

47
Q

6 factors that can affect the durability of concrete

A
  • water
  • chlorides
  • carbonation
  • sulphates
  • freeze-thaw cycles
  • abrasion
48
Q

4 things that can be done to improve the durability of concrete

A
  • using a low water-to-cement ratio
  • using admixtures
  • curing the concrete properly
  • protecting the concrete from the environment
49
Q

these are materials that are added to concrete during mixing to improve its properties

A

admixtures

50
Q

7 common types of admixtures

A
  • water-reducing admixtures
  • air-entraining admixtures
  • cementitious admixtures
  • retarding admixtures
  • accelerating admixtures
  • waterproofing admixtures
  • corrosion inhibitors
51
Q

these type of admixtures reduce the amount of water required to produce a workable concrete mix

A

water-reducing admixtures

52
Q

these type of admixtures introduce tiny air bubbles into the concrete mix

A

air-entraining admixtures

53
Q

these type of admixtures react with the cement in the concrete mix to improve its strength and durability

A

cementitious admixtures

54
Q

these type of admixtures slow down the setting time of the concrete mix

A

retarding admixtures

55
Q

these type of admixtures speed up the setting time of the concrete mix

A

accelerating admixtures

55
Q

these type of admixtures reduce the permeability of the concrete mix

A

waterproofing admixtures

56
Q

these type of admixtures protect the steel reinforcement in concrete from corrosion

A

corrosion inhibitors

57
Q

it is a versatile material that can be used in a variety of applications

A

structural lightweight concrete

58
Q

this material is a good choice for applications where weight, thermal insulation, or workability are important considerations

A

structural lightweight concrete

59
Q

3 applications of structural lightweight concrete

A
  • building structures
  • industrial applications
  • civil engineering applications

[4] PCD (4 decks)

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