Prelim

Question 1

Internal stresses are induced to counteract external stresses

Answer 1

Pre-stressed concrete

Question 2

Introduced pre-stressed concrete

Answer 2

Eugene Freyssinet

Question 3

Allow predetermined, engineering stresses to be placed in members to counteract stresses that occur when the unit is subjected to service loads

Answer 3

Prestressed concrete

Question 4

Is a method in which compression force is applied to the reinforced concrete section

Answer 4

Prestressing

Question 5

Types of prestressing

Answer 5

External or internal prestressing
Pre-tensioning or post-tensioning
Linear or circular prestressing
Full, limited or partial prestressing
Uniaxial, biaxial or multi-axial prestressing

Question 6

Two basic methods of applying prestress to a concrete member

Answer 6

Pre-tensioning

Post-tensioning

Question 7

Tendons are tensioned against some abutments before the concrete is placed

Answer 7

Pre-tensioning

Question 8

Tendons are tensioned after the concrete has hardened

Answer 8

Post-tensioning

Question 9

Popular post tensioning system

Answer 9

Freyssinet system
Magnel blaton system
Giffort-udall system
Lee-mccall system

Question 10

Is a single unit made of steel

Answer 10

Wire

Question 11

Two, three or seven wires are wound to form this

Answer 11

Strands

Question 12

A group of strands or wires

Answer 12

Tendons

Question 13

A group of tendons

Answer 13

Cables

Question 14

A tendon can be made up of single _______

Answer 14

Steel bar/ bar

Question 15

May consist of single wires, multi-wire strands or threaded bars and are most commonly made from high tensile steels, carbon fiber or aramid fiber

Answer 15

Tendons

Question 16

Tendons may be located within the concrete volume

Answer 16

Internal prestressing

Question 17

Tendons may be located wholly outside of concrete volume

Answer 17

External prestressing

Question 18

Has prestressing tendons permanently bonded to the surrounding concrete

Answer 18

Bonded post tensioning

Question 19

Allowing the tendons permanent freedom of longitudinal movement relative to the concrete

Answer 19

Unbonded post-tensioning

Question 20

Consist of bundle high-strength strands placed inside ducts

Answer 20

Tendon grouting

Question 21

Comprise individual high-strength strands coated in an anti-corrosion grease or wax

Answer 21

Tendon coating

Question 22

Prestressing tendons undergoes a gradual reduction with time from the instant when the steel is first tensioned due to various causes

Answer 22

Loss of prestress

Question 23

Factors to the loss of prestress

Answer 23

Immediate losses

Differed losses

Question 24

Immediate losseso

Answer 24

Elastic shortening loss
Friction loss
Anchorage slip

Question 25

Differed losses

Answer 25

Stress relaxation | Shrinkage and creep of concrete

Question 26

Shortening of concrete compressed during stressing as the two occur simultaneously

Answer 26

Elastic shortening loss

Question 27

Curvature effect and wobble effect

Answer 27

Friction loss

Question 28

When the tendon is tensioned, and the jack is released to transfer prestresses to concrete, the friction wedges employed to grip the wires slip over a small distance before the wires are firmly housed causing ________

Answer 28

Anchorage slip

Question 29

The stretched tendons will lose some of its induced stress due to this phenomenon

Answer 29

Stress relaxation

Question 30

Drying the concrete as accompanied by a reduction in volume

Answer 30

Loss due to shrinkage

Question 31

The strain increases and the concrete element shortens

Answer 31

Loss due to creep

Question 32

Located as described in ACI at end of the third span

Answer 32

Construction joint

Question 33

Stages of design

Answer 33

Jacking stage Service load stage Factored load stage Handling and transpo stage

Question 34

When tensile force in prestress is transferred to concrete

Answer 34

Jacking stage

Question 35

When long term volume changes have occured

Answer 35

Service load stage

Question 36

When the strength of member is checked

Answer 36

Factored load stage

Question 37

Extreme fiber stress in compression (NSCP)

Answer 37

0.6fci'

Question 38

Extreme fiber stress in compression at ends

Answer 38

0.7fci'

Question 39

Concrete tensile strength at ends

Answer 39

0.5sq.root of fc'

Question 40

Extreme fiber stress at other locations (simply supported)

Answer 40

0.25 sq.root of fc'