The control tension force of the prestressed steel strand construction design refers to the tension of the steel strand before the anchor clamp after the prestressing is completed. Therefore, when calculating the theoretical elongation of the prestressed steel strand, the distance between the anchor points at both ends of the steel strand should be used as the calculated length of the steel strand. However, during the prestressing, the controlled tension force of the steel strand is controlled at the jack tool anchor. Therefore, for the convenience of control and calculation, the distance between the anchor points at both ends of the steel strand plus the working length of the steel strand in the tensioning jack is generally used as the calculated length of the theoretical elongation of the prestressed steel helai. During the prestressing of the steel strand, most of the exposed part of the steel strand is wrapped by the anchor and jack. The tension elongation of the steel strand cannot be directly measured on the steel strand. Therefore, the tension elongation of the steel strand can only be calculated by measuring the piston stroke of the tension jack. However, the amount of anchor retraction during the entire process of prestressing the steel strand should also be subtracted. The load-bearing capacity of the steel strand should be 4-6 times the total traction force .