PCD

Question 1

A method of prestressing where the tendons (steel cables or rods) are
stretched and anchored before the concrete is poured and cured.

Answer 1

Pre-tensioning

Question 2

The process of applying an initial compressive force to concrete
members before they are subjected to service loads

Answer 2

Prestressing

Question 3

A method of prestressing where the tendons are installed in ducts
within the concrete after it has been cast and cured, and then stressed to apply a
compressive force

Answer 3

Post-tensioning

Question 4

Steel cables, rods, or bars used in prestressing concrete. They are the
components that are stretched and stressed to provide the compressive force

Answer 4

Tendons

Question 5

The device or system used to secure the ends of the tendons in both pretensioning and post-tensioning systems.

Answer 5

Anchorage

Question 6

Tubes or channels embedded in the concrete that contain the tendons during the
post-tensioning process. They protect the tendons and allow for the application of
prestress.

Answer 6

Ducts

Question 7

Release of StressThe process of transferring the prestressing force from the tendons
to the concrete, often done after the concrete has reached sufficient strength

Answer 7

Release of Stress

Question 8

The initial force applied to the tendons during the prestressing
process, which is transferred to the concrete.

Answer 8

Prestressing Force

Question 9

The portion of the initial prestressing force that remains in the
concrete member after accounting for losses due to factors such as elastic deformation,
shrinkage, and relaxation.

Answer 9

Effective Prestress

Question 10

The reduction in the effective prestress force over time due to
factors like creep, shrinkage, relaxation of the tendons, and other effects.

Answer 10

Losses of Prestress

Question 11

The gradual increase in deformation under a constant load over time,
which affects the amount of prestress that is retained in the concrete.

Answer 11

Concrete Creep

Question 12

The reduction in the volume of concrete as it dries and cures, affecting the
prestressing force.

Answer 12

Shrinkage

Question 13

The decrease in the stress within the tendons over time due to
the gradual reduction in the tension they carry.

Answer 13

Relaxation of Tendons

Question 14

The way in which the internal forces are spread throughout the
concrete member, influenced by the prestressing forces

Answer 14

Stress Distribution

Question 15

A beam that has been prestressed to improve its loadcarrying capacity and reduce deflection.

Answer 15

Prestressed Concrete Beam

Question 16

A flat, horizontal structural element that has been
prestressed, commonly used in floors and roofs.

Answer 16

Prestressed Concrete Slab

Question 17

Devices or systems used to securely attach the ends of the tendons to the
concrete structure.

Answer 17

Anchorages

Question 18

The adhesion between the tendons and the surrounding concrete, which allows
the transfer of stress.

Answer 18

Bonding

Question 19

The condition where the strains in the prestressed concrete
member are consistent with the stress-strain relationship of both the concrete and the
tendons.

Answer 19

Strain Compatibility

Question 20

A system in which the tendons are bonded to the concrete to
ensure that the prestress force is effectively transferred.

Answer 20

Stress-Bonded System

Question 21

Description: When the tendons are stressed, the concrete immediately experiences a
reduction in prestress due to its elastic deformation.
Impact: This is more significant in post-tensioned members, where the concrete shortens under
the load of the tendons.

Answer 21

Elastic Shortening

Question 22

➢ Description: Over time, concrete experiences deformation under sustained loads, known as
creep.
➢ Impact: Creep causes a gradual loss of prestress as the tendons elongate and the concrete
continues to deform.

Answer 22

Creep of Concrete

Question 23

➢ Description: Concrete shrinks as it dries and hardens, leading to a reduction in the prestress
force.
➢ Impact: This loss can be significant in the early days of curing, especially in thin sections

Answer 23

Shrinkage of Concrete

Question 24

1. Description: Steel tendons experience a reduction in stress over time when they are held
   at a constant strain. This phenomenon is known as relaxation.
2. Impact: This can lead to a decrease in the prestressing force, especially in high-strength
   steel.

Answer 24

Relaxation of Steel Tendons

Question 25

1. Description: Some losses can occur at the anchorage points where the tendons are
   anchored. This may involve friction and slippage.
2. Impact: These losses can be minimized with proper design and detailing.

Answer 25

Losses Due to Anchorage

Question 26

Different mixes and curing conditions can affect creep and
shrinkage.

Answer 26

Type of Concrete

Question 27

Temperature and humidity can influence drying
shrinkage and creep rates.

Answer 27

Environmental Conditions:

Question 28

Longer durations typically result in greater losses due to creep
and relaxation.

Answer 28

Duration of Load

Question 29

The type of steel and its properties, including yield strength
and elasticity, impact relaxation losses.

Answer 29

Tendon Properties

Question 30

Calculated based on the modulus of elasticity of the concrete.

Answer 30

Elastic Shortening