多塔悬索桥主缆与鞍座滑动失稳临界跨径研究

选取中塔刚度和避免中塔塔顶处的缆鞍滑动是多塔悬索桥设计的两个关键问题.通过理论推导,研究了加劲钢箱梁和钢桁梁多塔悬索桥的刚性和柔性中塔的缆鞍滑动临界跨径,对比分析了缆鞍滑动特性并讨论了抗滑安全系数的取值问题.研究结果表明,抗滑安全系数主要与恒、活载的比值以及跨径有关,且随跨径的增长而增大.当跨径达到临界跨径时,刚性中塔的主缆能自动满足抗滑条件;柔性中塔的临界跨径随塔顶水平相对位移的增加接近线性减小.

Study on Critical Span for the Anti-slip Stability between Main Cable and Saddle of Multi-Span Suspension Bridges

The stiffness of middle tower and the anti-slip stability between cable and saddle on the top of middle tower are the key issues of designing multi-span suspension bridges.The critical span for the anti-slip stability on the rigid and flexible middle tower is established through theoretical analysis.Then,a comparative study on the anti-slip capacity of the bridges with box girder and truss grider is conducted.Finally,the principle of choosing anti-slip factor is discussed.The results indicate that anti-slip factor is mainly related to the ratio of dead load to live load and the length of span,and the larger the span is,the bigger the factor is.When the critical span is reached,the anti-slip requirement on the rigid middle tower is satisfied automatically.The critical span of flexible middle tower decreases approximately linearly with the increase of the displacement of tower.