独柱塔自锚式悬索桥锚固横梁结构空间受力分析

Analysis of Spatial Load on Anchor Beam for Single Pylon Self-anchored Suspension Bridge

南京江心洲大桥边跨主缆锚固大横梁设计独特,结构受力非常复杂。为了获得锚固横梁局部应力的大小与分布规律,对其传力途径进行研究,以通用有限元程序为计算平台,采用空间索单元模拟横梁中配置的预应力束以及主缆束股,三维块体元模拟混凝土锚固横梁,应用二次开发技术,建立精细三维有限元模型。在此基础上采用合理的加载模式对锚固横梁在空缆阶段和成桥状态2种不同工况进行应力计算与分析。结果表明:在空缆与成桥2种状态下锚固横梁的应力值与分布规律变化较大;为保证锚固横梁在施工过程中的受力状态处在合理的范围之内,锚固横梁中配置的大量预应力束应配合主缆束股的内力变化而分批次张拉。

Jiangxinzhou Bridge in Nanjing is a single-pylon spatial cable self-anchored suspension bridge, whose side span main cable anchorage beam design is unique and structural loading is complex. In order to get its partial stress value and distribution as well as its force transfer path, prestressing tendons and main cable was simulated by spatial cable element, concrete anchor beam was simulated by 3D block element, and a 3D refinement finite element model was established with secondary development technology based on the platform of general finite element program. On this basis, reasonable load pattern was used to its spatial structural analysis, by which its force transfer path and stress distribution under free cable construction stage and finished stage were obtained. The results show that （1） stress value and distribution change greatly between the two stages; （2） prestressing tendons of anchor beam should be tensioned by stages according to change of main cable internal force to ensure the mechanical state of anchor beam in a reasonable range in the construction process.