施工期48h内锚下有效预应力时间及温度效应修正

Correction of Time and Temperature Effects of Effective Prestress Under Anchor Within 48 Hours During Construction Period

为了揭示后张法PC梁在张拉后、压浆前48h内的预应力损失变化规律,通过现场试验和数值模拟结合的方法,对张拉施工后48h内的20m预应力混凝土梁的锚下有效预应力变化开展研究,建立了考虑温度效应影响下有效预应力变化值的修正模型。研究结果表明:实际工程中预应力损失率呈对数函数形式增长,前500min损失较大;实际测试中的预应力损失比数值模拟理论计算值偏大,最大可达3.43%。

In order to reveal the law of change in prestress loss of post-tensioned PC beam after tensioning and 48 hours before grouting, the changes to the effective prestress of a 20-meter prestressed concrete beam within 48 hours after tensioning were studied by field test and numerical simulation. A correction model considering the effective prestress variation under the influence of temperature effects was established. The research results show that the prestress loss rate in actual engineering increases in logarithmic function, and the loss in the first 500 minutes is larger;the prestress loss in the actual test is larger than that of theoretical calculation, and the maximum is 3.43%.