The pre-stressing of concrete has several advantages as compared to traditional reinforced concrete (RC) without pre stressing. A fully prestressed concrete member is usually subjected to compression during service life. This rectifies several deficiencies of concrete. The following text broadly mentions the advantages of a pre-stressed concrete member with an equivalent RC member. For each effect, the benefits are listed.
A) Section remains un-cracked under service loads
- Reduction of steel corrosion
- Increase in durability.
- Full section is utilized
- Higher moment of inertia (higher stiffness)
- Less deformations (improved serviceability).
- Increase in shear capacity
- Suitable for use in pressure vessels, liquid retaining structures.
- Improved performance (resilience) under dynamic and fatigue loading.
B) High span-to-depth ratios
- Larger spans possible with prestressing (bridges, buildings with large column-free spaces)
- Typical values of span-to-depth ratios in slabs are given below.
For the same span, less depth compared to RC member.
- Reduction in self weight
- More esthetic appeal due to slender sections
- More economical sections.
C) Suitable for precast construction The advantages of precast construction are as follows:
- Rapid construction
- Better quality control
- Reduced maintenance
- Suitable for repetitive construction
- Multiple use of formwork
- Reduction of formwork
- Availability of standard shapes.
The following figure shows the common types of precast sections.
Although prestressing has advantages, some aspects need to be carefully addressed.
- Pre-stressing needs skilled technology. Hence, it is not as common as reinforced concrete.
- The use of high strength materials is costly.
- There is additional cost in auxiliary equipment.
- There is need for quality control and inspection.