本文针对钢筋混凝土结构设计规范 TJ10-74后张法构件,完成第二批预应力损失后,未考虑混凝土弹性压缩有所恢复引起的预应力钢筋有效应力值的增加,从预应力阶段实际的应力变化过程出发,推演出正确反映这一阶段的混凝土有效预应力计算公式。并通过实例分析了《规范》公式(115)的精度,指出了该公式对后张法轴心受拉构件超出了工程实用的误差范围与不宜采用。 In this paper, for the reinforced concrete structural design specification TJ10-74 post-tensioned structural members, after the completion of the second batch of prestress loss, the increase of the effective stress value of the prestressed steel bar caused by the restoration of the elastic compression of the concrete is not considered, and the actual stress from the prestress phase is not taken into account. Starting from the process of change, deductions correctly reflect the calculation formula for concrete prestressing at this stage. The accuracy of formula (115) of “Specification” is analyzed through an example, and it is pointed out that this formula is not suitable for the post-tensioned axial tension member beyond the practical error range of engineering.