Abstract: The maximum stress of main cables in the long-span suspension bridge is located at the main saddle，and secondary stress is relatively large in this place． Several secondary stress calculation methods of the first segment main cable near saddle can be established by different assumptions． For a long-span suspension bridge，secondary stress calculation results got by different methods are compared with experimental results，and the secondary stress and safety factors of the first segment main cable near saddle in the dead load and live load are calculated． The results show that the calculated results got by different methods are in good agreement with the measured ones when the deformation in the main cable is small． The secondary stress calculations must take the slippage between the wire and the change of ultimate shear friction force with the increase of axis force of the main cable into account when the deformation in the main cable is large． The safety factors of the first segment main cable near saddle reach 2． 0，and the secondary stress of this location can be reduced by taking appropriate measures in the construction process．

Key words: long-span suspension bridge, main cable, secondary stress, safety factors

摘要： 大跨度悬索桥主缆的应力在主鞍座处最高，主缆次应力在此处也比较大。采用不同的假设条件可建立主鞍座 处主缆二次应力的几种计算方法，针对某实桥，将不同计算方法所得到的计算结果与实测结果进行了比较，并对悬 索桥索鞍出口处主缆在恒载和活载作用下的二次应力和安全系数进行了计算。结果表明: 在主缆变形较小时，不同 计算方法所得到的计算结果与实测值较吻合| 在主缆变形较大时，索鞍出口处主缆的二次应力计算需将钢丝的滑移 及钢丝间极限摩擦剪力随主缆轴力增大而发生改变的影响考虑进去。通过计算所得到的索鞍出口处主缆的安全系 数达到2． 0，并且在施工过程中采取适当的措施可以减小这一位置处的二次应力。

关键词: 大跨度悬索桥, 主缆, 二次应力, 安全系数