空间索面地锚式悬索桥结构行为研究

Research on Structural Behavior of Ground-Anchored Suspension Bridge with Spatial Cable Planes

为研究空间索面地锚式悬索桥结构行为,以主跨610 m的空间索面地锚式悬索桥——重庆市郊铁路跳磴至江津线跨江轨道专用桥为背景,采用SNAS软件建立大桥有限元模型,分析主缆横向矢跨比、主缆弯扭刚度对结构受力特性的影响以及施工期间空间索面线形变化规律。结果表明:随主缆横向矢跨比增大,结构竖向刚度基本不变,横向刚度提高;主缆弯扭刚度仅对成桥状态近塔处主缆局部线形及少数吊索索力有所影响,对结构整体受力基本无影响;施工期间以空缆状态为基准进行索夹定位和横向预偏角放样时需考虑主缆转动角的影响,而以主缆横向对拉后状态为基准则可不考虑;采用5对拉杆张拉主缆进行横向定位可有效控制主缆横向位置及吊索横向倾角接近成桥状态。

The under-construction suspension bridge carrying a section of Metro Line 5(specifically the Tiaodeng-Jiangjin Section of Metro Line 5)over the Changjiang River in Chongqing is used as a case to study the structural behavior of the ground-anchored suspension bridge with spatial cable planes.The finite element models of the bridge were established in SNAS to analyze the effects of transverse rise-to-span ratio as well as bending and torsional stiffness of main cables on the load bearing behavior of the bridge and trace the variation of the geometrical shape of the spatial cable planes.The results demonstrate that as the transverse rise-to-span ratio increases,the vertical stiffness of the bridge almost keeps constant,while the transverse stiffness is improved.The bending and torsional stiffness of the main cable only influence the geometrical shape of the section of main cable and the tension of a few hanger cables near the tower,and are negligible to the global load bearing performance of the structure,after completion of the bridge.Due to that the locations of cable clamps and the lateral preformed angles of the main cables were determined on the empty main cables,instead of the tensioned main cables,the effect of rotational angles of the main cables should be considered.It is recommended to use five lateral bracings in the transverse positioning of the main cables,so as to effectively control the attitudes of the main cables and allow the lateral drift angles of hanger cables to reach the design level.