以鹅公岩轨道交通专用桥为工程背景,对自锚式悬索桥极限承载力及其安全性评价方法进行研究.从材料的单轴本构模型出发,介绍杆单元与纤维梁单元弹塑性刚度矩阵的计算方法,基于U.L.列式编制相应的杆系有限元计算程序.对活载独立增大及恒活载同比增大两种典型荷载模式下四种工况的极限承载力计算结果进行分析,揭示了自锚式悬索桥的破坏过程中位移、截面刚度变化规律及失效机制.结合JTG/T D65-01-2007《公路斜拉桥设计细则》中大跨度桥梁非线性分析时主梁安全系数的规定,根据荷载效应等效原则,推导活载安全系数的计算公式,通过与规范对比分析发现,其计算结果更为严格,并就该公式及规范评价吊索与主缆安全性出现的结果不一致性进行分析.%Based on the prototype of Egongyan Transit Bridge,the ultimate bearing capacity and safety evaluation method of the self anchored suspension bridge were studied.Based on the uniaxial constitutive model of the material,the calculation methods of the elastic-plastic stiffness matrixs of the rod and fiber beam element were introduced,and the finite element calculation program was developed based on the U.L.formulation.The calculation results of the ultimate bearing capacity of four working conditions under two typical load modes,namely independent increase of live load and joint increase of both live and dead loads were analyzed to study the displacement,section stiffness variation and failure mechanism of the bridge.According to the requirement on the safety factors of the main girder of large span bridges under nonlinear analysis specified by the Guidelines for Design of Highway Cable-stayed Bridge and the principle of equivalent load effect,the calculation formula of the safety factor of live load was deduced.Compared with design codes,the results showed that the calculation formula is more rigorous.Meanwhile,the inconsistency between results of the safety of the sling and main cable evaluated by the calculation formula and specified by design codes were analyzed.
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