大跨斜拉桥预应力索塔锚固区受力机理及试验

Theoretical and experimental study on pre-stressed cable-pylon anchorage in long-span cable-stayed bridges

摘要:

为保证斜拉桥索塔锚固区受力可靠,基于受力特征和平面框架分析模型,推导了不同受力阶段预应力小半径大吨位环向U型预应力索塔锚固区控制截面环向应力的计算公式．结合实际工程,建立空间有限元模型,并进行预应力索塔锚固区斜向加载的足尺模型试验,得到了预应力施加阶段、正常使用阶段和非对称加载阶段塔壁的应力分布规律,通过与试验结果进行对比,验证了本文提出公式的适用性．研究结果表明:斜拉索水平力主要由环向预应力筋承担,非对称受力对锚固区受力影响不大,所提出的简化方法可为索塔锚固区设计提供参考．

Abstract:

Anchorage zone is crucial for the cable-stayed bridges and a plane frame model is presented to investigate the performance of the anchorage zone embedded with small radius U-shape pre-stress system, in pylon under different loading stages based on a summary and an analysis of the behavior of pre-stressed cable-pylons, and the expression for calculating the horizontal stress in the critic position of cable-pylon was deduced. A full-scale model test under oblique loading was conducted to analyze the mechanical behavior of pre-stressed cable-pylon according to a practical project and the stress distribution patterns of main members were obtained. The experimental results confirm the practice of the proposed method. The results show that, the pre-stress provides most vertical force to balance the cable load, and the behavior of anchorage zone has slight difference between asymmetrical and symmetrical loadings.