郁江特大桥主塔锚固区应力状态仿真分析

Simulation Analysis on the Stress State in the Anchorage Zone of the Main Tower of Yujiang Super Major Bridge

南广(南宁—广州)客运专线郁江特大桥为主跨228m的双塔双索面铁路双线钢桁梁斜拉桥。为确保其主塔锚固区的受力安全,根据主塔锚固区截面、配筋及预应力的设计参数,采用有限元软件ANSYS及等效荷载法和实体力筋法建立三维仿真计算模型,分析主塔锚固区在主塔施工完毕、第1次和第2次拉索完成3种工况条件下的应力状态。结果表明:在3种工况条件下,主塔锚固区的绝大部分节点以受压为主,切应力很小,而且压应力最大的节点位于预应力筋附近,最大压应力为28MPa;主塔锚固区受到的拉应力主要分布在主塔内侧,方向接近竖直向上,一般不超过4MPa;与主塔施工完毕时相比,第1次和第2次拉索完成后,锚固区顺桥向发生微小不对称位移,预应力筋附近的最大压应力有所减小,主塔内侧拉应力有所增加,预应力有效地抵消了拉索传递过来的拉力;混凝土抗压强度及钢筋抗拉强度均有较大的安全裕量,锚固区变形很小,满足结构的刚度要求。

Yujiang super major bridge of Nan-Guang （Nangning to Guangzhou） passenger dedicated line is a double-track steel truss cable-stayed bridge which has two towers and double cable planes and a main span of 228 m.To make sure the anchorage zones of the main towers work safely,we analyzed its stress state at the moment when the main towers were completed,and the cables were stretched at the first and the second time.Using the finite element software ANSYS,by means of equivalent load method and physical reinforcement method,3D simulation model of the main towers＇ anchorage zones of Yujiang super major bridge was established according to its design parameters of cross section,reinforcement and prestress.Results showed that,under three working conditions,most of the nodes in the anchorage zones of the main towers bore compressive stress mainly and the shear stress was very small.Besides,the nodes bore the biggest compressive stress were near the tendons and the maximum compressive stress was 28 MPa.The tensile stress borne by the anchorage zone was vertical and mainly distributed around the inside of the main towers,which didn＇t exceed 4 MPa generally.Compared with the time when the main towers were completed,tiny asymmetrical displacement along the direction of the bridge occurred in the anchorage zones of the main towers after the completion of the cables being stretched at the first and the second time.The maximum compressive stress near the tendons became smaller.The tensile stress around the inside of the main towers became bigger and the prestress counteracted the tensile force from the cables effectively.Both the compressive strength of concrete and the tensile strength of reinforcement had larger safety margin.The deformation in the anchorage zones was very small and could meet the demand for structural rigidity.