What Reinforcements are used in the Process of Prestressing?

Reinforcements used in the process of prestressing: Especially in case of prestressing, we are using strands of Steel and it's called tendons.

Tendons are made of high strength Steel.

Three major types of reinforcements which are used in Prestressing:

Spalling R/f Equilibrium R/f Bursting R/f

Combination of reducing the structural thickness reduced conventional reinforcements quantities and fast construction often results in un prestressed structure.

Thank You.

Reinforcements used in the process of prestressing:

Especially in case of prestressing, we are using strands of Steel and it’s called tendons.

Tendons are made of high strength Steel.

Three major types of reinforcements which are used in Prestressing:

1. Spalling R/f
2. Equilibrium R/f
3. Bursting R/f

Combination of reducing the structural thickness reduced conventional reinforcements quantities and fast construction often results in un prestressed structure.

Thank You.  

Following are the three major types of reinforcement used for prestressing work:

1. Spalling reinforcement: spalling enforcement is used to resist the spelling stresses which are produced behind the loaded area of anchor blocks.
2. Equilibrium reinforcement: to apply a prestressing load sequential over the rebars, equilibrium reinforcement are used.
3. Bursting reinforcement: at the line of action of the load maximum bursting stresses produced. To resist these stresses bursting reinforcement is provided.

In prestressing, we use strands of steel usually called as tendons. They are made of high strength steel. However, there are other terms in pre stressing based on the size of the tendon. The following are the terms in an increasing order of size.

1. Wire – small wire (single)
2. Strand – 2 or more wires
3. Tendon – group of strands
4. Cable – Group of tendons
5. Bar – single bar – dia of 10 mm or more

The type of steel used in prestressing may be:

1. Cold worked steel
2. Stress relieving steel
3. Strain tampered steel

The following properties of the steel are appreciated:

1. High strength property of steel (min of 980 Mpa for bars)
2. Adequate ductility
3. Bendability ( for harping )
4. High bond strength (Crucial for pretensioned members because the stress transfer in the former is only through bond)
5. Less stress relaxation ( To minimize losses)
6. Less corossion

Note that the permissible stress in prestressing steel is not more than 80% of yeild strength.

Permissible stress = 0.8fy

This fy is found just like any HYSD bar by considering the 0.2% proof stress.

High tensile steel is used for prestressed concrete.

According to strength, can be classified as 1470MPa, 1570MPa, 1670MPa, 1770MPa and 1860MPa.

According to diameters

4mm, 4.8mm, 5.0mm, 5.1mm, 6.0mm, 6.35mm, 7.0mm, 7.8mm. etc

Basically that wire called tendon

There are three different types of reinforcement are used in prestressing are:

1. Equilibrium reinforcement – when the prestressing load is applying on some Anchorage, then that type reinforcement are used.

2. Spalling reinforcement – when the spalling stress is induced behind the loaded area of anchorage block, then we can use spalling reinforcement.

3. Bursting reinforcement – maximum bursting stress is induced when tensile stress is developing during prestressing then the bursting reinforcement is used.