Determine the meaning of Relaxation of Steel
If the strain in steel is kept constant, it is seen that stresses in it reduce with time. It is called as relaxation of steel. Tendons in prestressed concrete are provided with a particular strain (due to stretching) and this b'&ain is kept constant inside concrete. Due to relaxation of steel, stresses in tendons reduce with time, leading to what is called as 'loss of prestress due to relaxation of steel'. The relaxation losses in prestressing steels vary with type of steel, initial prestress, age and temperature, etc.