Abstract: Based on the test data of 8 beams,this paper studies the fatigue behavior of unbonded P.P.C.beam.In the paper,parameters which influnce the fatigue behavior are mainly disused. The Parameters are the coefficient of characteristic val ue or fatigue load and the coefficient of fatigue load range.And the formula of unbonded P.P.C beam are established bythe auttlor.In the end of the paper,results calculable by the formula are compared with the given by other documents.

Key words: unbond, fatigue, shear strength

摘要： 本文根据8片无粘结部分预应力混凝土梁的疲劳试验结果，对在较高疲劳荷载上限和疲劳下限条件下，无粘结部分预应力混凝土梁的斜向开裂机理和斜截面疲劳抗剪强度进行了分析和研究．并给出了无粘结部分预应力混凝土梁斜截面疲劳抗剪强度折减系数的计算公式．讨论了影响疲劳破坏的两个主要因素荷载特征值和荷载幅值系数与动载循环次数的关系，并给出了它们的回归公式．最后，文章把本文公式计算结果与试验结果进行了对比分析．

关键词: 无粘结, 疲劳, 抗剪强度