Recognize the losses of prestress
Recognising the losses of prestress which take place after the prestressing OF concrete structural elements, it is to be appreciated that prestresses of an order of 100 to 250 N/mm2 is generally lost due to various reasons. If the losscs of stresses are to be a small portion of the initially induced prestresses. the tendon material should be able to sustain a very high stress - say about 1200 to 2000 N/mm2. This high value of strength may not be available in mild steel and high strength steel which is used in reinforced cement concrete. This tact clearly emphasises the necessity of having tendon steel of a high strength grade.