为克服斜拉桥混凝土索塔锚固区布置环形预应力筋在受力和施工方面的不足，提出一种新型单向预应力布置型式． 该布置型式下预应力筋长度较短，其损失规律和施工工艺与普通长束预应力筋有所不同． 为研究这种直向短束预应力筋的损失特点，进行了足尺模型试验，重点对摩阻(包括孔道摩阻和锚具摩阻)损失，锚固回缩损失以及伸长量控制方法进行了研究，并对锚下预应力筋进行了短期观测． 结果表明:预应力总损失约为 26%，锚固回缩损失占总损失的50%以上;孔道摩阻损失占总损失的 12%左右，锚圈口摩阻损失占20%，此二项不同于大多文献和规范建议的作忽略考虑;“伸长量控制”在短束预应力施工控制中同样适用，但其对施工误差极为敏感，必须保证张拉质量，控制误差应放宽至 ±9%．

As the way of arranging circular prestress tendons in the PC (Prestressed Concrete) pylon anchorage zones of cable-stayed bridges has its disadvantages in terms of mechanical performance and construction，a new arrangement of prestress tendons by the name of one-way straight tendons is put forward． Under this kind of arrangement，the prestress tendons are relatively short，and their prestress loss laws and construction control are different from the tendons with common length． In order to investigate the loss characteristic of this kind of short straight prestress tendons，the friction loss (the duck friction and the anchorage friction) and the loss due to anchorage set as well as the elongation control are emphatically analyzed by a full-scale model test． Moreover，the prestress tendons under anchor are observed for a short time． The results show that (1) the average total loss of prestress is 26%;(2) in the total loss，the loss due to anchorage set，the duct friction loss and the anchorage head friction loss respectively account for more than 50%，about 12% and 20%，and the latter two types of loss should not be ignored as most articles and codes have recommended; and (3) the elongation control is still applicable in the construction of short prestress tendons，but in view of its exquisite sensitivity to the construction error，the construction quality must be guaranteed and the permissible error should be extended to ±9%．