An Effective Method to Improve the Stiffness of Arch-beam Fixed Arch Bridges

Abstract:

The main beam of a Arch-beam fixed arch bridge acts as a rigid tie rod to balance the thrust of archs, but it also has the adverse effect of structural stiffness decrease. This has limited the application of this type of arch bridge on high-speed railways. In order to solve this problem, this paper proposes a new arch bridge. The method is, first of all, to add 10 rigid diagonal bars between each ribs and the main beam to form 11 triangle structures with the main beam and the each ribs segments. As far as possible, the arch ribs and the main beam are equally divided by triangular corner points so that the line stiffness of the arch ribs and the main beam are improved. Secondly, according to the original structure displacement envelope diagram, it is guaranteed that the triangular corner points fall at the position of maximum displacement and the mid-span of main beam so that the weakness of arch ribs is strengthened. Studies have shown that the overall stiffness of the new arch bridge can be significantly improved under the condition that the material increases little or even the same. In this paper, the fatigue and temperature responses are also discussed in detail, and finite element analysis shows that the structure also has good adaptability to fatigue and temperature. And the superior stiffness characteristics of the new arch bridge are particularly suitable for high-speed railway bridges.