What is prestressed concrete PDF?
Prestressed concrete is a structural two-component material, high- tensile strength steel and high strength concrete, which permit prespecified compression stresses being applied on the structural element.
What is prestressed concrete and its principle?
The principle behind prestressed concrete is that compressive stresses induced by high-strength steel tendons in a concrete member before loads are applied will balance the tensile stresses imposed in the member during service.
What are the types of prestressed concrete?
According to the construction method, there are two kinds of prestressed concrete:
- Pre-tensioned concrete.
- Bonded Post-tensioned concrete.
- Unbonded Post-tensioned concrete.
What is prestressed concrete used for?
It is now commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, prestressed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.
What are the methods of prestressing?
There are two methods of prestressing:
- Pre-tensioning: Apply prestress to steel strands before casting concrete;
- Post-tensioning: Apply prestress to steel tendons after casting concrete.
- The member shortens due to the force and this relieves some of the prestress;
- The concrete shrinks as it further cures;
What is P line and C line in prestressed concrete?
Line of action of P-force is called the P-line. The P-line is nothing but the tendon line itself. The line of action of the C-force is called the C-line or Pressure line. Hence in the absence of any external bending moment the P-line and the C-line coincide.
What are the limitations of prestressed concrete?
Disadvantages of Prestressed Concrete
- Prestressed concrete requires high-quality dense concrete of high strength.
- It requires high tensile steel, which is 2.5 to 3.5 times costlier than mild steel.
- Prestressing process requires complicated tensioning equipment and anchoring devices.
What is prestressed and its types?
The basic types of prestressing are: Precompression with mostly the structure’s own weight. Pre-tensioning with high-strength embedded tendons. Post-tensioning with high-strength bonded or unbonded tendons.
What are two methods used for prestressing?
Where is prestressing used?
Pre-tensioned concrete is most commonly used for the fabrication of structural beams, floor slabs, hollow-core planks, balconies, lintels, driven piles, water tanks and concrete pipes.
What are the two general methods of prestressed concrete?
There are two methods of prestressing: Pre-tensioning: Apply prestress to steel strands before casting concrete; Post-tensioning: Apply prestress to steel tendons after casting concrete.
How is prestressed concrete made?
In the real life, high tensile strength steel wires are inserted into the beam section and they are stretched and anchored, then released. Now the steel tendon wants to gain its original length and tensile stresses are transformed into a compressive stress in the concrete.