Prestressed concrete is currently very popular in the construction industry due to its benefits. It brings a greater economy and finished the construction.
Mainly, there are two types of prestressing methods.
- Prestressing
- Post Tensioning
In prestressing, prestress bars are stressed initially and then the construction of concreting work is done. In post-tension construction, as the name implies, the stressing of the wires will be done after the concreting work is completed.
The article Bridge design to BS 5400 states the methods of designing a post-tension beam.
Let’s discuss the advantage of the prestressed concrete.
Advantages of Prestressed Concrete
- Prestressed concrete can be designed avoiding the tensile cracks in the concrete. Then the whole section will be in compression and there are no tensile caracks. It increases the durability of the structure.
- The load-carrying capacity is comparatively higher. It can be used to support large spans.
- Since high strength steel wires are used for the construction, it reduces the area of reinforcements to be provided.
- Further, the cost of the materials is comparatively less when compared with normal reinforced concrete members. Section size and area of steel to be used are less.
- They can be used to support larger spans.
- The deflection of the prestress elements is comparatively less when compared with reinforced concrete members of similar nature.
- Based on the location of the tendon profile, the load-carrying capacity is varying.
- The use of prestressed members is more economical when repetitive productions are made.
- Since the section has less weight, it can be transported.
- Finishing of the concrete work is grater
- When there is repetitive work, the same beam can be used widely. In bridge construction, there are standard beams that only required repetitive production as the same type can be used in all applicable locations.
Disadvantages of Prestressed Concrete
- Requires skilled labour
- Much attention shall be made on quality control.
- Special techniques are required to apply prestressing forces and Anchorage the wires.
- Its is requires high strength concrete and they are costly.
- It requires complicated tensioning equipment.
- It is very difficult to make the formworks and special compactions methods shall be used to avoid the honeycombs.
- Work shall be actively supervised.
- Higher technical knowledge is required.
