Abstract: In order to reduce the risk of progressive collapse of half-through tied arch bridges caused by local failure, the structural analysis method of applying bridge redundancy to design optimization, operation and maintenance was studied with an example of a typical half-through tied arch bridge. Firstly, the deterministic measures and the deterministic direct analysis method in NCHRP Reports were chosen to carry out the redundancy evaluation. Secondly, the intact model and the damaged models were established using the finite element software ANSYS to obtain the load-deformation curves. Finally, the effect of different damage modes on capacity and functionality of the bridge structure were analyzed as well as the redundancy indices, and suggestions for design optimization, operation and maintenance were offered. The results show that failure of a middle pier bearing next to the arch foot, general suspenders or long suspenders decreases the ultimate capacity of the bridge by about 30%, and that the maximum deflection of the main girder before overall failure decreases by 10% to 30 as well. The redundancy ratio for functionality rf is related to bridge stiffness. The redundancy ratio for ultimate capacity ru is influenced by the bridge failure mode corresponding to the certain loading mode. The redundancy ratio for damaged conditions rd is associated with the boundary conditions of the damaged member in bridge structure. In view of design optimization, stiffness of the middle span deck system and the strength of suspenders should be improved. In view of maintenance, it is advised that the maintenance level be heightened, that the supervision of overloading be strengthened, and that suspenders be specially maintained.

Key words: bridge engineering, redundancy, deterministic direct analysis method, tied arch bridges, bridge design, bridge maintenance

摘要： 为了降低局部构件破坏导致中承式系杆拱桥连续倒塌的风险，以一座典型中承式系杆拱桥为例，研究了将桥梁结构冗余度应用于设计优化 和运营养护的结构分析方法。采用美国国家公路合作研究项目报告中的确定性准则与确定性分析方法，利用有限元软件ANSYS求得桥梁完好状态与 局部破坏状态的荷载-位移曲线，分析不同局部破坏模式对桥梁结构承载能力与正常使用的影响及冗余度计算结果，提出设计优化与运营养护建议 。结果表明：拱脚处中墩支座破坏、一般吊杆或长吊杆的断裂导致系杆拱桥极限承载能力下降约30%，整体失效时主梁最大挠度减小10%至30%；正 常使用冗余率rf与桥梁结构刚度有关，极限承载冗余率ru与不同加载方式下桥梁整体失效模式相关，局部破坏冗余率rd与破坏构件在桥梁结构中 所处边界条件相关；从设计优化角度，应适当提高中跨桥面系刚度与吊杆强度，从运营养护角度，应提高养护水平，加强对超载行为的管制，并 对吊杆重点养护。

关键词: 桥梁工程, 冗余度, 确定性分析方法, 系杆拱桥, 桥梁设计, 桥梁养护