Lecture 2

Question 1

occur during prestressing of tendons, and transfer of prestress to concrete member

Answer 1

Immediate losses

Question 2

losses occur during service life of structure

Answer 2

Time dependent

Question 3

Types of Immediate Losses

Answer 3

-Elastic Shortening
-Friction
-Anchorage Slip

Question 4

Types of time dependent Losses

Answer 4

-Creep
-Shrinkage
-Relaxation

Question 5

generated due to the curvature of the tendon and the vertical component of the prestressing force

Answer 5

friction

Question 6

The wobble in the tendon is effected by the following variables

Answer 6

•Rigidity of sheathing

• Diameter of sheathing

•Spacing of sheath supports

•Type of tendon

•Type of construction

Question 7

The friction due to wobble is assumed to be proportional to the following:

Answer 7

•Length of the tendon
• Prestressing force

Question 8

is defined as the decrease in stress with time under constant strain

Answer 8

Relaxation of steel

Question 9

The relaxation depends on the

Answer 9

type of steel, initial prestress (f) and the temperature