斜拉索非对称布置对多塔斜拉桥力学性能的影响

Influence of Asymmetric Arrangement of Cables on Mechanical Properties of Multi⁃tower Cable⁃stayed Bridge

为了提高多塔斜拉桥的结构刚度,在现有斜拉索布置方式的基础上,提出了交叉索+非对称索面的组合布置方式。利用有限元软件ANSYS建立多塔斜拉桥有限元模型,研究在高跨比、中边塔高比、中塔刚度及主梁刚度变化的情况下,新型斜拉索布置方式对主梁和桥塔变形所产生的影响。结果表明:在用钢量相同的条件下,与传统布置方案、交叉索布置方案和非对称索面布置方案相比,采用新型布索方案后中塔的塔顶水平位移分别减小了9%、1%和20%,加载跨挠度减小了19%、15%和11%。以非对称索面为基础,调整高跨比、中边塔高比、中塔刚度及主梁刚度,当交叉索设置在距中塔0.7L(L为主跨长度)左右时,中塔塔顶偏位和加载跨挠度达到最小值,对结构整体刚度提升效果最优,与理论计算结果相吻合。非对称索面的多塔斜拉桥结构刚度随交叉索设置数量的增加呈先增后减的趋势。

In order to improve the structural stiffness of multi-tower cable-stayed bridge,based on the existing cable layout,a combined layout of cross cable and asymmetric cable plane was proposed.The finite element model of multitower cable-stayed bridge was established by using the finite element software ANSYS.The influence of the new cable arrangement on the deformation of the main beam and the bridge tower was studied under the condition of the change of the height-span ratio,the height ratio of the middle tower and side tower,the stiffness of the middle tower and the stiffness of the main beam.The results show that under the condition of the same amount of steel,compared with the traditional arrangement scheme,the cross cable arrangement scheme and the asymmetric cable plane arrangement scheme,the horizontal displacement of the middle tower is reduced by 9%,1%and 20%respectively,and the deflection of the loading span is reduced by 19%,15%and 11%respectively.Based on the asymmetric cable plane,the height-span ratio,the height ratio of the middle tower and side tower,the stiffness of the middle tower and the stiffness of the main beam are adjusted.When the cross cable is set at about 0.7L(L is main span length)from the middle tower,the deflection of the top of the middle tower and the deflection of the loading span reach the minimum value,which has the best effect on the overall stiffness of the structure,which is consistent with the theoretical calculation results.The structural stiffness of multi-tower cable-stayed bridge with asymmetric cable plane increases first and then decreases with the increase of the number of cross cables.