利用AN SY S分析软件,模拟单筋作用下腹板自由端的竖向压应力的分布规律,指出滞后张拉的意义并提出滞后张拉合理距离应大于一倍梁高;通过永胜大桥工程实例计算,比较了悬臂施工过程中竖向预应力筋在3种不同的张拉顺序下,腹板竖向压应力的分布规律,验证了滞后张拉的合理性。 Using AN SY S analysis software to simulate the distribution law of vertical compressive stress at the free end of the web under the effect of single rib, pointing out the significance of lag tension and putting forward that the reasonable distance of lag tension should be more than double the height of girder. Through the engineering example of Yongsheng Bridge , The vertical compressive stress distribution of vertical prestressing tendons in cantilever construction process under three different tension sequences was compared and the rationality of lag tension was verified.