Robustness assessment of a cable-stayed bridge

Abstract

The failure of one structural element can lead to the failure of further structural elements and thus to the collapse of large structural sections or the entire structure. Such dispro- portionate collapses have been discussed and investigated for some years, but mainly for build- ings. Generally, structures can be made collapse resistant by ensuring a high level of safety against local failure or by increasing their robustness. Robustness has been defined as the insen- sitivity to local failure. Increasing the robustness of cable-stayed bridges means to design for the loss of cables. The sudden loss of cables is a dynamic event and must be investigated in non- linear dynamic analyses. For the design, only the maximum responses are of interest. For this, quasi-static analyses using dynamic amplification factors to account for the dynamic effects are advised. This paper examines the structural response of a cable-stayed bridge to the loss of one cable by means of dynamic analyses including large displacements. The effects of cable sag, transverse cable vibrations and structural damping are determined and dynamic amplification factors are computed. Finally, conclusions are drawn as to the collapse behavior of cable-stayed bridges taking into account non-linear material behavior.