交叉索布置方式对多塔斜拉桥力学性能的影响

为提高主跨设交叉索的多塔斜拉桥刚度，改善其受力性能，在现有的交叉索布置方式基础上，提出间隔布置、非对称布置两种新的交叉索布置方式。建立主跨设交叉索的三塔至五塔斜拉桥有限元模型，与现有布置方式对比，分析新的交叉索布置方式对活载作用下主梁挠度、中塔塔顶位移、结构竖向基频及中塔内力的影响。结果表明：在拉索用钢量相同的条件下，与原有的交叉索布置方式相比，交叉索间隔2根索布置时，三至五塔斜拉桥的中塔塔顶位移减小3.9%~8.9%，主跨跨中下挠减小0.03%~4.9%，竖向基频增大1.40%~4.3%，中塔塔底弯矩减小2.2%~6.6%；交叉索采用非对称布置时，中塔塔顶位移减小8.2%~9.2%，主跨跨中下挠减小0.01%~6.6%，竖向基频增大0.7%~2.7%，中塔塔底弯矩减小5.6%~7.7%。间隔布置、非对称布置可有效提高交叉索对中塔的约束效果，提高结构刚度、改善桥塔受力。采用非对称布置的结构刚度最大、桥塔受力最小。

Influence of crossed-cables arrangement on mechanical performance of multi-tower cable-stayed bridge

To improve the stiffness and mechanical performance of the multi-tower cable stayed bridge with crossed cables on the main span, spaced arrangement and asymmetric arrangement were proposed on the basis of existing crossed cable arrangement. The finite element model of three towers to five towers cable-stayed bridge with crossed cables on the main span was established. Compared with the existing arrangement, the influence of new crossed cable arrangements on the deflection of the main girder, the displacement of the top of middle tower, the fundamental frequency and the internal force of the middle tower was analyzed. The results show that under the condition of the same steel consumption of cables, compared with the original arrangement of crossed cables, when the crossed cables are arranged with two cables apart, the top displacement of the middle tower of three towers to five towers cable-stayed bridges is reduced by 3.9 %~8.9%, the deflection of the main span is reduced by 0.03%~4.9%, the vertical fundamental frequency is increased by 1.40%~4.3%, the bottom bending moment of the middle tower is reduced by 2.2%~6.6%; when the asymmetrical arrangement is adopted to crossed cables, the top displacement of the middle tower is reduced by 8.2%~9.2%, the deflection of the main span is reduced by 0.01%~6.6%, the vertical fundamental frequency is increased by 0.7%~2.7%, and the bottom bending moment of the middle tower is reduced by 5.6%~7.7%. The structure with asymmetrical arrangement has the largest rigidity and the least stress on the middle tower. The spaced arrangement and asymmetric arrangement can effectively improve the restraint effect of the crossed-cables on the middle tower, increase the structural rigidity, and improve the internal force of middle tower.