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为研究混凝土梁中后张预应力损失的分布特征及其对各种不确定因素的敏感性,以概率数值模拟为基本手段,得到各分项预应力损失及预应力总损失的概率分布特征,并对预应力损失进行了区间估计。将各影响因素划分为施工、设计和材料3类,分析了预应力损失对各类因素的敏感性。结果表明:预应力总损失可用对数正态分布描述;95%置信概率下预应力总损失的上、下限偏离均值可达20%以上,各因素不确定性对预应力损失影响不容忽视;各类因素的敏感程度依次为施工条件、材料性能和设计因素,其中张拉控制应力、预应力筋弹性模量和预应力筋面积分别在3类因素中的影响最为显著;各分项预应力损失中,管道局部偏差对摩阻损失的影响强于管道摩擦,预应力筋越长对锚具变形损失影响越弱,而混凝土收缩徐变损失对徐变的敏感程度要强于收缩。
In order to study the distribution characteristics of post-tensioned prestress loss in concrete beams and their sensitivity to various uncertainties, probabilistic numerical simulation is taken as a basic measure to get the probability distribution characteristics of prestressed losses and prestressed total losses. The interval of prestress loss is estimated. The factors are divided into three categories of construction, design and materials, and the sensitivity of prestress loss to various factors is analyzed. The results show that the total loss of prestress can be described by logarithmic normal distribution. The upper and lower deviation of prestressed total loss under 95% confidence probability can reach over 20%, and the influence of various factors on prestress loss can not be ignored. The sensitivity of the factors is followed by the construction conditions, material properties and design factors. Among them, the tension control stress, the elastic modulus of prestressing tendons and the area of prestress tendons have the most significant influence on the three kinds of factors respectively; , The influence of pipeline local deviation on friction loss is stronger than that of pipeline. The longer the prestressed tendons, the weaker the deformation loss of anchorage is, while the shrinkage and creep loss of concrete is more sensitive to creep than shrinkage.