Effective framework for seismic analysis of cable-stayed-bridges, Part 1: Modeling of the structure and of the seismic action

The spatial variability of the strong ground motion leads to significant aspects in the structural response of long-plan structures, such as long-span and medium-span bridges. In this study the structural responses of a prestressed concrete cable-stayed-bridge, with medium length span of 300 m, under 30 different seismic events, in both cases of synchronous and asynchronous motion at the base of the structure have been compared. Although the studies are principally conducted by a 3-D model of the structure, which one will call “frame model”, developed using the finite element software Ansys, the structure has been studied using another model, which one will call “shell model”, in order to evaluate how the differences in the modeling lead to different results. In the part 1 of the study, the authors put in evidence the differences among the models response in terms of modal characteristics of the principals modes. The comparison of the results obtained in both the models shows the similar behaviour of the two models, confirmed by the small differences in percentage of the values reached by monitored static and kinematical.