First answer, prestressed tension control to give priority to with stress control, as a review of the control method of elongation value. That is to say, the tension control as the main control. Secondly, according to the calibration of the jack and oil to determine the oil meter reading; Third: according to the drawings or design requirements to determine the initial stress for many general control stress of 10% to 20%. Fourth: according to the number of steel strand and cross-sectional area to convert the stress strength; Fifth: the initial control force values of stress and control stress transformation into the school report of the linear equation, so that we can get the corresponding oil meter readings, the fuel meter readings are tensioned main control of the data you want, factoid-mad must reach this value; 6; According to the different stages of the drawings are given to calculate the theoretic elongation of steel strand length.