Based on Code for Acceptance of Constructional Quality of Concrete Structures (GB50204-2002), the relative tensioned value of pretension steel strand should be verified, and the allowable difference between the actual and theoretic elongation is 6%.

• 《混凝土结构工程施工质量验收规范》规定：当采用应力控制方法张拉时，应校核预应力筋的伸长值，实际伸长值与设计计算理论伸长值的相对允许偏差为±6%25。