Pre stress is the process of giving artificial permanent strains to a building before or at the time of application of the external loads. Specially produced wires or bunches in different types, sizes and durability are used to prestress the concrete. Prestressed concrete steel elements are produced out of high carbon, vanadium alloyed special wire rods by detensioning after a significant load and a regular heat treatment. In prestressed concrete structures, pre-stress applied initially decreases in time because of the shrinkage and straining of the concrete and loosening of the pre-stressing steel. For this reason, loosening of the steel under fixed height or the feature defined as voltage loss has become one of the parameters taken into consideration in the design of the prestressed concrete buildings.
Advantages of the products gained low relaxation feature;
• Higher yield and tensile strength,
• Superior durability against fatigue and corrosion,
• Consistent load strain relationship,
• Superior straighten property.