Structural system identification of cable-stayed bridges with observability techniques

Cable-stayed bridges are highly statically redundant, light and flexible structures. This complexity highlights the role of the structural system identification (SSI) method in the calibration of the actual properties of the simplified models of these structures. This study proposes the first application of observability techniques to SSI of cable-stayed bridges. This method enables to define which subset of actual structural variables should be measured on site to identify mechanical properties, such as Young's modulus, area and inertia, or stiffnesses (EA and EI) of deck, pylon and stay cables. The effects of the inclination and inertia of the stay cables and the existence of pylon and deck cracking in the observability of different cable-stayed bridges are studied. The results obtained are validated by the models of actual cable-stayed bridges.