INTRO

Question 1

High flexural strength compared to RC beams

Answer 1

Prestressed Concrete

Question 2

T OR F
Tension zone is maximized if not eliminated

Answer 2

F (MINIMIZE)

Question 3

Minimum strength of prestressed concrete

Answer 3

34.5 MPa

Question 4

Methods of Prestressing

Answer 4

-Pretension
-Post - tensioned

Question 5

Tensioning of tendons is done before concrete pouring

Answer 5

Pretension

Question 6

Percentage of strength of cured concrete after 24 hours in Pretensioning

Answer 6

70%

Question 7

Tensioning of the tendons is done after concrete has initially cured

Answer 7

POST-TENSION

Question 8

Stages of Prestressing

Answer 8

• Jacking Stage
• Transfer or Initial Stage
• Service Stage

Question 9

Initial stresses are induced in a member to counteract the external stresses which are developed due to the external loads or service loads

Answer 9

Prestress

Question 10

is basically concrete in which internal stresses of a suitable magnitude and ⚫ distribution are introduced so that the stresses resulting from the external loads are counteracted to a desired degree.

Answer 10

Prestressed concrete

Question 11

A stretched element used in a concrete member of structure to impart prestress to the concrete.

Answer 11

Tendon

Question 12

A device generally used to enable the tendon to impart and maintain prestress in concrete.

Answer 12

Anchorage

Question 13

A method of prestressing concrete in which the tendons are tensioned before the concrete is placed. In this method, the concrete is introduced by bond between steel & concrete.

Answer 13

Pretensioning

Question 14

A method of prestressing concrete by tensioning the tendons against hardened concrete. In this method, the prestress is imparted to concrete by bearing.

Answer 14

Post-tensioning

Question 15

Loss of strength is above 17%

Answer 15

Pretension

Question 16

loss of strength is not more than 15%

Answer 16

post-tension

Question 17

developed due to bearing

Answer 17

post-tension

Question 18

Prestressing _______ is a single unit made of steel

Answer 18

Wires

Question 19

Two, three or seven wires are wound to form a prestressing __________

Answer 19

Strands

Question 20

A group of strands or wires are wound to form a prestressing ___________.

Answer 20

Tendon

Question 21

A group of tendons form a prestressing _________

Answer 21

Cable

Question 22

A tendon can be made up of a single steel bar. The diameter of a bar is much larger than that of a wire.

Answer 22

Bars

Question 23

High strength steel contains:

Answer 23

• 0.7 to 0.8% carbons,
• 0.6% manganese,
• 0.1% silica

Question 24

Source of Prestressing Force

Answer 24

-Hydraulic Prestressing
-Mechanical Prestressing
-Electrical Prestressing

Question 25

This is the simplest type of prestressing, producing large prestressing forces. The hydraulic jack seed for the tensioning of tendons, comprises of calibrated pressure gauges which directly indicate the magnitude of force developed during the tensioning.

Answer 25

Hydraulic Prestressing

Question 26

In this type of prestressing, the devices includes weights with or without lever transmission, geared transmission in conjunction with pulley blocks, screw jacks with or without gear drives and wire-winding machines. This type of prestressing is adopted for mass scale production

Answer 26

Mechanical Prestressing

Question 27

In this type of prestressing, the steel wires are electrically heated and anchored before placing concrete in the moulds. This type of prestressing is also known as thermoelectric prestressing

Answer 27

Electrical Prestressing

Question 28

Concrete Cover for pretensioned members

Answer 28

20 mm

Question 29

Advantages of Prestressing

Answer 29

1. Section remains uncracked under service loads 2. High span-to-depth ratios 3.Suitable for precast construction

Question 30

Internal stresses are induced in a member to counteract the external stresses which are developed due to the external loads or service loads

Answer 30

PRESTRESS

Question 31

is basically concrete in which internal stresses of a saitable magnitude and distribution are introduced so that the stresses resulting from the external loads are counteracted to a desired degree.

Answer 31

PRESTRESSED CONCRETE

Question 32

A method of prestressing concrete in which the tendons are tensioned before the concrete is placed. In this method, the concrete is introduced by bond between steel & concrete

Answer 32

PRETENSIONING

Question 33

A method of prestressing concrete by tensioning the tendons against hardened concrete. In this method, the prestress is imparted to concrete by bearing.

Answer 33

Post-tensioning

Question 34

A stretched element used in a concrete member of structure to impart prestress to the concrete.

Answer 34

Tendon

Question 35

A device generally used to enable the tendon to impart and maintain prestress in concrete.

Answer 35

Anchorage

Question 36

This is when the maximum tension stress is equal to the modulus of rupture

Answer 36

Cracking stage

Question 37

This is when the ultimate capacity of the section has been reached

Answer 37

Ultimate Stage

Question 38

Concrete cover for post-tensioned members

Answer 38

30 mm or size of the cable

Question 39

used for the tensioning of tendons, comprises of calibrated pressure gauges which directly indicate the magnitude of force developed during tensioning

Answer 39

Hydraulic Jack

Question 40

Electrical prestressing is also known as

Answer 40

Thermoelectric prestressing