What is pre stressing of concrete?
What is pre stressing of concrete?
Prestressing is the process by which a concrete element is compressed, generally by steel wires or strands. Precast elements may be prestressed during the construction process (pre-tensioning) or structures may be stressed once completed (post-tensioning).
What is the reason for using pre stressed concrete?
Prestressing can reduce the volume of concrete required in construction, lowering the use and transportation of materials, as well as boosting durability and service life. Concrete is intrinsically resistant to compressive stresses, but its resistance to tension is much lower.
What are the types of pre stressed concrete?
According to the construction method, there are two kinds of prestressed concrete:
- Pre-tensioned concrete.
- Bonded Post-tensioned concrete.
- Unbonded Post-tensioned concrete.
How is pre stressed concrete made?
In pretensioning, the steel is stretched before the concrete is placed. High-strength steel tendons are placed between two abutments and stretched to 70 to 80 percent of their ultimate strength. Concrete is poured into molds around the tendons and allowed to cure.
What are the advantages of pre stressing?
The main benefit of prestressing is that the build up of tension under service loads and possible cracking may be avoided or reduced to a low level. The effective stiffness of the cross-section is increased, leading to a reduction in deflections.
What are the properties of prestressed concrete?
Properties of various materials used in prestressed concrete must suit the requirements which are connected with the performance of prestressed concrete….The basic requirements of prestressed concrete are:
- High Strength Capacity.
- Low Shrinkage.
- Low Creep.
- High Durability.
What is pre stressing and explain different types of prestressing?
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 is concrete stress?
Stress strain curve of concrete is a graphical representation of concrete behavior under load. It is produced by plotting concrete compress strain at various interval of concrete compressive loading (stress). Concrete is mostly used in compression that is why its compressive stress strain curve is of major interest.
How does prestressed concrete work?
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 methods of prestressing?
Different systems are adopted for pre-tensioning and post tensioning.
- Types of Prestressing Systems.
- Pre-Tensioning System.
- Post-Tensioning System. Freyssinet System. Magnel Blaton system. Gifford Udall System. Lee McCall System. Other Methods of Prestressing.
