Post Tensioning

Description:-

Introducing Pre-stressing is creation for known permanent stresses in a member of structure before the full dead and live loads are applied. These stresses are created by means of high tensile steels tendons, which are tensioned and then anchored mechanically to the member being pre-stressed. This offset or counter reacts the stress, which the subsequent loading will produce. This also modifies the behavior of the material of which the member or structure is composed. For example, concrete those have relatively low tensile strength, after pre-stressing it will behave as if it were ductile and as if it had high tensile strength.

APPLICATION:-

In building projects such as bridges and quaysides, void tubes make possible large spans thanks to a reduction in dead weight and thus permit good technical, aesthetic and economic solutions.Bridges and long span of beams account for a large percentage of pre-stressed structures,. There are many general and specialized application like circular containment vessel, Buildings slabs, Rock Anchorages, etc. The Bridge construction the advantages are obvious. For large span and smaller structural depths which would be impracticable in reinforced concrete can be achieved, while for shorter span, construction depths are less, more elegant appearance, lighter foundation and greater durability.

The pre-stressing of building frames and floor slabs achieves considerable reduction of dead loading and saving in foundation cost, reduces the number of columns living more versatility in planning ,reduces or eliminates cracking and reduce the deflection of beams and slabs.

Railway sleepers now are almost entirely of pre-stressed concrete, pipes, poles and powers are axially pre-stressed so as to resist the building in any direction. Specialized application includes reactor pressure vessels of Nuclear Power station recent application is the storage of low temperature liquids in cryogenic tanks, which are of pre-stressed concrete