Dynamic behaviour of curved cable-stayed bridges

During the last decades, curved cable-stayed bridges have been regularly accepted due to their ability to cross long spans, for aesthetic reasons because of their enhanced geometric configurations and to the reduced costs involved in the bridge and roof construction. However, such structures are typically showed to several special geometric shapes, which lead to a different dynamic ability. Therefore, in order to verify the dynamic performance of the structure, it is necessary to investigate the effects on dynamic behaviour of such particular geometric shape and structure by considering both serviceability and ultimate working conditions. The enormous development in the field of the design of more splendid and ambitious civil structures like bridges, stadiums with irregular shapes as the landmark of the city. Regarding design, existing codes on curved and cable-stayed bridges, roofs etc. We discuss the different structure shapes and analysis the dynamic ability. These require in-depth analysis concerning unlikely predictable behavior often necessary FE model's simplification. Thus arose the necessity for structural engineers to develop solid experimental tools able to identify dynamic and static structural properties in order to calibrate, update and validate the FE model used at the design phase. Fortunately, this was already accomplished by the necessity that rose early on in the field of Electronics and Mechanical Engineering, through years’ efforts by both theory and practice circles to develop System Identification and Modal Analysis techniques. Still today the most widely used techniques in the field of experimentations provide the use of instrumentation like an impulse hammer, an electro-dynamic shaker, mass vibrator, capable of exciting the dynamic property of the structures in a controlled form. However, the price and as a consequence, the inadequate availability of input-output modal identification techniques, together with the difficulty to excite large civil structures, led the researcher to a more feasible method: Operational Modal Analysis (OMA). This thesis provides the theoretical fundamentals of structure health monitoring especially focused on the FE model updating Optimization Process on curved cable-stayed bridge. A global view of techniques, tools, and physical assumptions made in the Vibration measurements phase and System Identification phase are provided in order to understand how to get the experimental data needed and how they should be treated to be easily compared with the numerical ones. Building a finite element model, which accurately reflects the true structure's stiffness and mass distribution, can improve the precise of dynamic analysis results of curved cable-stayed bridges.