温州瓯江北口大桥中塔索鞍抗滑移构造研究

温州瓯江北口大桥为主跨800m的三塔四跨悬索桥,中塔采用刚度较大的钢筋混凝土塔。为解决中塔索鞍与主缆之间的抗滑移问题,提出在鞍槽内设置水平摩擦板、竖向摩擦板、水平摩擦板+竖向摩擦板3种方案来提高中塔索鞍与主缆间的名义摩擦系数,对索鞍进行抗滑移计算,采用MIDAS Civil软件建立索鞍有限元模型对其进行受力分析,并对比3种方案的抗滑移效果。结果表明:水平摩擦板索鞍、竖向摩擦板索鞍、水平摩擦板+竖向摩擦板索鞍的名义摩擦系数分别为0.392、0.422、0.412,抗滑安全系数分别为2.63、2.83、2.76,3种方案均能显著提高索鞍的抗滑移性能;水平摩擦板与索鞍的连接构件局部应力较大,且施工困难;全竖向摩擦板索鞍各部位的应力相对较小且分布较均匀,并通过相关试验验证了施工可行性,该桥最终采用全竖向摩擦板防滑索鞍方案。

Study on Anti-Slip Structure of Saddle on Middle Tower of Oujiang River North Estuary Bridge in Wenzhou

Oujiang River North Estuary Bridge in Wenzhou is a three-tower and four-span suspension bridge with a main span of 800 m.The reinforced concrete towers with higher stiffness are adopted in constructing a middle tower.In order to solve the problem of anti-slip between the main cable and the main saddle in the middle tower,we proposed three schemes,namely,installing horizontal friction plate,installing vertical friction plate,and installing horizontal friction plate and vertical friction plate,to improve the nominal friction coefficient between the main saddle and the main cable,and calculated the anti-slip of the saddle.Moreover,we established a finite element model of the saddle by using the software MIDAS Civil to analyze the mechanical behavior of the saddle,and compared the anti-slip effects of the three schemes.The results show that the nominal friction coefficients of saddle with horizontal friction plate,saddle with full vertical friction plate,saddle with horizontal friction plate and vertical friction plate are 0.392,0.422 and 0.412,respectively,and the anti-slip safety factors are 2.63,2.83 and 2.76,respectively,therefore the anti-slip performance of saddle can significantly be improved after adopting the three schemes;the local stress of the connection between horizontal friction plate and saddle is larger,and the construction of horizontal friction plate is difficult;The stress of the full vertical friction plate is relatively small and uniform,and the feasibility of construction is verified by relevant tests.Finally,the anti-slip saddle with full vertical friction plate is recommended for the bridge.