chp 10 Flashcards
1
Q
advantages of pre-stressing
A
- reduction of steel corrosion
- increase in durability
- full section is utilised
2
Q
limitations of pre-stressing
A
- use of high strength materials is costly
- additional cost in auxiliary equipment
- need for quality control and inspection
3
Q
describe pre-tensioned concrete
A
- protects the tendon from corrosion and allows for direct transfer of tension
- cured concrete adheres and bonds to the bars and when the tension is released it id transferred to the concrete as compression by static friction
4
Q
types of pre-tensioned concrete
A
- lintels
- floor slabs
- beams
5
Q
describe bonded post-tensioned concrete
A
concrete is cast around a plastic, steel or aluminium curved duct, to follow the area where otherwise tension would occur in the concrete element. once concrete is hardened, tendons are tensioned by hydraulic jacks that react against the concrete member itself
6
Q
describe unbonded post-tensioned concrete
A
- provides each individual cable permanent freedom of movement relative to the concrete
- each individual tendon is coated with a grease and covered by a plastic sheathing formed in an extrusion process
7
Q
where is bonded post-tensioned concrete used
A
construction of various bridges
8
Q
disadvantage of unbonded post-tensioned concrete
A
a cable can destress itself and burst out of the slab if damaged
