体外预应力组合梁桥预应力损失计算

Calculation of Prestress Loss of Externally Prestressed Composite Girder Bridges

为准确计算体外预应力组合梁桥预应力损失值,在已有研究的基础上,总结导致该类型梁桥预应力损失的6个关键因素(预应力筋回缩和锚具变形、预应力筋与转向块之间的摩擦、预应力筋松弛、混凝土徐变、混凝土收缩、温度变化),并分别推导了相应的简化计算方法。计算预应力筋回缩和锚具变形以及摩擦引起的预应力损失时采用材料力学方法和平衡原理;计算预应力筋松弛引起的预应力损失时参考预应力混凝土梁的相关经验公式并结合试验结果进行修正;计算混凝土徐变、收缩以及温度效应引起的预应力损失时近似采用力法原理和等效荷载法。

To accurately calculate the prestress loss values of externally prestressed composite girder bridges, the six critical factors （the prestressing tendon withdrawal and anchor deformation, friction between prestressing tendon and deviator, prestressing tendon relaxation, concrete creep, concrete shrinkage and temperature changes） that cause the prestress loss of such type of the bridges are summarized and the corresponding simplified calculation methods are respectively derived on the basis of the existing researches. The prestress loss caused by the prestressing tendon withdrawal, anchor deformation and friction can be calculated, using the material mechanics method and the equilibrium principle. For calculation of the prestress loss caused by the pres- tressing tendon relaxation, the relevant empirical formulae of prestressed concrete beams may be referred and should be modified according to the tests and when the prestress loss caused by the concrete creep, shrinkage and temperature changes is calculated, the force method principle and the equivalent load method can be approximately applied.