Abstract: Excessive rebar retraction is an important reason for the loss of prestressing force in post-tensioned reinforced concrete beams.The simplified method and accurate method of rebar retraction were put forward. The probability distribution statistics of 233 groups of test data were carried out, and the distribution hypotheses of probability model of 3 kinds of rebar retraction were put forward. The various distribution hypotheses were tested by Kolmogorov test method respectively.The results show that the retraction of clip is less than that of strand, and the relative displacement of clip and strand occurs.Simply calculating the retraction of steel bar through the retraction of clip will result in smaller test results.In practical engineering, the rebar retraction exceeds the standard, and the excessive depth of groove of limit plate is an important reason for the excessive rebar retraction.The rebar retraction obeys normal distribution.Based on this, the proposed normal distribution probability model of rebar retraction provides a favorable basis for the evaluation of actual rebar retraction and prestress loss caused by rebar retraction.The associated model of the simplified method and accurate method of rebar retraction can be used for quantitative assessment of rebar retraction amount in practical engineering.

Key words: bridge engineering, prestressed clip anchor, rebar retraction, probability distribution model, hypothesis test, normal distribution

摘要： 钢筋回缩量超标是后张法预应力钢筋混凝土梁预应力损失的重要原因。提出钢筋回缩量的简化和准确方法，对233组测试数据进行了 概率分布统计，提出了3种钢筋回缩量概率模型分布假设，使用柯尔莫哥洛夫检验法分别对各种分布假设进行检验。研究表明：夹片回缩量 小于钢绞线回缩量，夹片和钢绞线发生相对位移，通过夹片回缩量来简易计算钢筋回缩量会导致测试结果偏小；实际工程中存在钢筋回缩量 超标的情况，限位板槽深过大是钢筋回缩量超标的重要原因；钢筋回缩量服从正态分布，据此提出的钢筋回缩量正态分布概率模型为实际工 程钢筋回缩量以及其导致的预应力损失评估提供了有利依据。钢筋回缩量简化方法和准确方法关联模型可用于实际工程钢筋回缩量的定量评 估。

关键词: 桥梁工程, 预应力夹片锚, 钢筋回缩, 概率分布模型, 假设检验, 正态分布