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

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