In present state of development in field of prestressed concrete is due to continuous research done by engineers and scientists in this field during last 90 years while Jackson of San Francisco applied for a patent ?construction of artificial stone and concrete pavements?, in which prestress was introduced by tensioning reinforced rods set in sleeves.

Prestressed concrete is used in construction of long span bridges, industrial roofs, marine structures, nuclear pressure vessels, water retaining structures, railway sleepers etc and it also has a higher modulus of elasticity and small creep strain, resulting in smaller loss of prestressing in steel while prestressed concrete is one of construction material in building and bridge products around world.

The length of prestressing tendon between end of member and point where steel attains its full stress and adequate transmission length is necessary to reduce radial forces acting on concrete.

Due to utilization of concrete in tension zone, an extra saving of 15 to 30 percent in concrete is possible in comparison with reinforced concrete high tensile steels are used in prestressed members and its ultimate strength is equal to 2100n/mm2 and saving in steel are even higher, 60 ? 80 percent mainly due to high permissible stresses allowed in high tension wires.

Compression in concrete and tension in steel is developed by use of expanding cements due to its elastic property or expanding property, joint cement is an adhesive used primarily for attaching joint tape that is placed over beams whereas water cement ratio is ratio of weight of water to weight of cement used in a concrete mix.

A superior amount of rigidity is offered by prestressed concrete flexural members under working load conditions when compared with that offered by reinforced concrete members of equal dimensions.

Anchorage is term used to denote a device which helps tendons to transmit prestress to member and maintain it for design period, generally used to enable tendon to impart and maintain prestress in concrete and commonly used anchorages are Freyssinet, Magnel, Balton, Gifford-udall, Leon hardt etc.

The basic concept involved in analysis of prestressed concrete members is concept of combined direct and bending stresses used for columns whereas principle and shear stresses are formed in case of tensioning prestressed and reinforced structures, overhead stresses are formed while stresses in structures goes beyond safe limit provided by different codes.

Prestressed concrete is widely used in many branches of civil engineering and building construction and in recent days it is experiencing greatest growth in field of commercial building because of its acoustic properties and its ability to provide long open space.

In words of Guyon: ?re is no structural problem to which prestress cannot provide a solution, and often a revolutionary one, Prestress is more than a technique; it is a general principle? is description or explanation given by Guyon on prestressing.