In this system, forces are transmitted by bearing at end blocks while system eliminates loss of stress due to anchorage slip by screwing a nut and washer against end blocks and drawback of this system is that it cannot use curved tendons.

The temperature in bars is raised from 300 to 400degrees for a time duration of 3to 5 minutes, with this bar elongates up to 0.4 to 0.5%, empirical relations for estimation of current, voltage and power requirements of transformer are reported by Graduck.

The stresses in wires are not similar, even though all wires are been stretched toger, Freyssinet system involves application of heavy jacks which are economical force applied for stretching is about 250kn to 500kn which is maximum and is still inadequate.

In case of heating bar gets elongated and shortens after heating and after anchorages are applied on both sides which stretch bar, clamp splices are equipped with bolts and nuts since re will be a considerable reduction in tensile strength of up to 50 percent, se type of splice can be used only in locations where prestressing force can be sufficiently reduced by curvature of tendon due to friction.

Screw connectors are normally employed to splice large diameter high tensile bars which can be threaded at ends, torpedo splice consists of triple wedges for securing wires and entire unit is covered and protected by a sleeve, clamp splices are equipped with bolts and nuts with a series of clamp plates to house tendons between m for splicing of small diameter wires of 3-6mm.

In prestressing system, tendons are first tensioned between rigid anchorage blocks cast on ground or a column or a unit mould type pretensioning bed, prior to casting of concrete in moulds.

Freyssinet system of post tensioning anchorages which was developed in 1939, gave impetus to various new systems devised over years and at present, according to abeles re are over 64 patent post prominent systems used worldwide.

After process of cooling, bars get shortened but which can be known with fixed arrangement at both ends and period of cooling is observed as 12 to 15minutes, a steel metal sheath of enlarged diameter and sufficient length is generally used to cover splice, screw threaded connectors are not recommended for splicing heat treated prestressing steels, which are highly suspectable for stress corrosion.

The Freyssinet anchorage system is widely used in Europe and India consists of a cylinder with a conical interior through which high tensile wires pass and against walls of which wires are wedged by a conical plug lined longitudinally with grooves to house wires.

It has been found that structural elements ideally suited for chemical pre stressing include pipes, thin walls and slabs, shells; folded plates and composite columns as well as pre cast beams and columns.