小曲率半径预应力束张拉延伸量研究

Study of Tensioning Elongation of Sharp Curvature Radius Tendons

针对小曲率半径预应力束张拉延伸量比理论延伸量偏大这一现象,分析了影响小曲率半径预应力束张拉延伸量的挤压效应和束效应,提出了小曲率半径预应力束张拉延伸量的统一计算方法。考虑到小曲率半径预应力束曲线段的等效径向荷载引起的挤压效应,对孔道摩阻系数进行了修正。同时,分析了预应力束的束效应引起的钢绞线的重新排列,以及弯曲段等效径向荷载产生的径向位移,最后得出了适合小曲率半径预应力束张拉延伸量计算的理论方法,并通过多个工程实测数据进行校验。

In view of the phenomenon that the tensioning elongation of sharp curvature radius tendons is slightly greater than the theoretic elongation, this paper analyzes the squeeze effect and strand effect that affect the tensioning elongation of the tendons, and proposes an uniform method for calculating the tensioning elongation. In consideration of the squeeze effect due to equivalent radial load on the curvature sections of the tendons, the paper modifies the friction coefficients of the tendon ducts, and at the same time, also analyzes the re-arraying of the tendons due to the strand effect and the radial displacement due to the equivalent radial load. Finally, the paper provides the theoretic method suitable for calculating the tensioning elongation of the tendons, and checks the method as well by measurement data from several engineering projects.