The prestress developed in pre tensioning is due to bond between concrete and steel tendons, a method of prestressing concrete in which tendons are tensioned before concrete is placed at work site.

The concrete member which is prestressed by providing tensioned tendon are termed as internally prestressed members and existing space between edge of beam and abutments is filled with concrete using expanding cement.

In case of fully prestressed members which are free from tensile stresses under working loads cross-section is more efficiently utilized when compared with a reinforced concrete section that is cracked under working loads.

A stretched element used in a prestressed concrete member which serves purpose of transmitting prestress to concrete and it may be in form of high tensile steel wires, cables or strands.

Freyssinet attempted to introduce permanently acting forces in concrete to resist elastic forces developed under loads and this idea was later developed under name of prestressing while loading and bending phenomena occurs in a member while placing and during excessive loads and pre-straining occurs in prestressed concrete structures.

The use of prestressed concrete spread rapidly from 1935 onwards and many long span bridges, industrial shell roofs, marine structures, nuclear pressure vessels etc were constructed between 1945 and 1950 in Europe and United states.

In reinforced concrete members, prestress commonly introduced is by tensioning steel reinforcement while rings i.e stirrups are used while placing columns or foundation in structures, tendon is a stretched member of a prestressed concrete element which serves purpose of transmitting prestress to concrete and shortening of concrete phenomena occurs while placing of concrete.

Distortion principle of statically indeterminate structures is used by rotation or by displacement and in statistics a structure is statistically indeterminate when static equilibrium equation are insufficient for determining internal forces and reactions on that structure.

The prestressed concrete involves many architectural or construction related problems formulated due to curved surfaces and involve sophisticated erection problems, a high quality control is required for production of materials and while placing tendons and when members are subjected to a system of loads n existing problems due to long term creep moments are increased.

Shrinkage of concrete is due to moisture loss resulting in difference in volume results in contraction of concrete on drying and it is based on relative humidity, exposure time, quantity and type of aggregate, water cement ratio in mix.