Dynamic response analysis of CFST rigid frame tied arch bridge considering tie rod fracture

Abstract:

To facilitate the computation and analysis of the dynamic response of concrete-filled steel tubular (CFST) rigid-frame tied-arch bridges after tie rod fracture, a dynamic coefficient is introduced to account for the dynamic effects during the fracture process. An equivalent static calculation method incorporating the effect of tie rod fracture is proposed. The validity of the finite element modeling approach for simulating tie rod fracture was verified through comparisons with experimental results from a physical model test. A response analysis was carried out on a CFST rigid-frame tied-arch bridge to determine dynamic coefficients under various tie rod fracture scenarios. The results demonstrate that the tie rods should be regarded as the primary components in the dynamic analysis of such bridges after fracture. The in-plane bending moment of the piers and the horizontal displacement at the pier top can serve as supplementary indicators. In the case of single-side tie rod fracture, significant displacement occurs at the pier top on the fractured side, while displacement on the non-fractured side is negligible. The end crossbeam is subjected to shear and torsion. In contrast, under double-side fracture conditions, no torsion is generated in the end crossbeam on the fractured side, the axial force in the arch rib decreases, and the out-of-plane bending moment of the pier shows little variation. Based on the analysis, it is recommended to use a dynamic coefficient of 1.4 for single-side fracture and 1.6 for double-side fracture when applying the equivalent static method for assessing CFST rigid-frame tied-arch bridges considering the dynamic effect of tie rod fracture.