2 000 m级超大跨度悬索桥主缆架设影响参数研究

Research on Main Cable Erection Influential Parameters of Suspension Bridge with Span Length over 2000 m

为研究地球曲率、温度、主缆弹性模量以及加劲梁恒载误差对2000 m级超大跨度悬索桥主缆成桥线形的影响,以主跨2180 m的广州狮子洋大桥为背景,采用BNLAS软件建立主桥有限元模型,基于单一变量法对上述参数的影响性进行分析。结果表明:地球曲率对超大跨度悬索桥的主缆成桥线形影响较大,可通过在索股制造时对分跨标记点进行修正以避免该因素的影响;主缆成桥线形对温度变化极其敏感,建议增加温度测试断面数量以得到更为精确的温度场分布,据此对主缆成桥线形进行修正;主缆弹性模量影响索股的无应力长度,进而影响主缆成桥线形,需增加钢丝弹性模量的测试精度及抽样比例,得到符合实际主缆弹性模量的检测值,据此修正主缆成桥线形;加劲梁恒载误差对主缆成桥线形的影响很大,主缆架设前需要对钢梁进行称重并测试铺装材料的容重,根据实际重量重新计算主缆成桥线形,并且在铺装层施工时精确控制铺装层厚度。

The Shiziyang Suspension Bridge in Guangzhou that has a main span of 2180 m is used as a case to study the influence of a series of parameters on the geometry of main cables of the suspension bridge with a main span length over 2000 m,including the curvature of the earth,temperature,elastic modulus of main cable as well as the deviation of stiffening girder dead loads.A finite element model of the main bridge was developed in BNLAS to analyze the influence of the parameters aforementioned,based on univariate method.It is shown that the curvature of the earth is critical to the main cable geometry after completion of the bridge,which can be circumvented via modifying the span division marking points during the cable strands manufacturing process.The main cables are quite sensitive to thermal effect,hence it is suggested to increase the thermal testing cross-sections to attain more accurate temperature field distribution,and the geometry of the main cables after the completion of the bridge can be modified on this basis.The elastic modulus of main cables governs the stress-free lengths of constituent strands,consequently weighing against the geometry of the main cables after the completion of the bridge,thus it is necessary to increase the accuracy of the elastic modulus testing and sampling ratio of the steel wires,so as to obtain the tested values compliant with the actual elastic modulus of the main cable,and based on which,the geometry of the main cable after the completion of the bridge can be modified.The dead loads of stiffening girder exert substantial influence on the geometry of the main cable after the completion of the bridge,the steel girders must be weighed before the erection of main cables and the unit weight of the paving materials should be tested,then the geometry of the main cable should be recalculated in accordance with the actual weight,and the pavement thickness should be accurately controlled during paving.