Vibration analysis and structural identification of a curved multi-span viaduct

摘要

This work continues a line of research aimed at the development ofa dynamically based monitoring program of bridges in the area ofFriuli Venezia Giulia, Italy. The main infrastructure of thesurvey program is the curved fifteen-span post-tensioned concreteviaduct considered in this paper. The viaduct consists of threecontinuous girders separated by expansion joints and supported onpiers by means of elastomeric seismic isolators. Output-onlyvibration tests under traffic loads were carried out to extractthe dynamic parameters of the first vibration modes of thestructure. The experimental characteristics were compared withthose predicted by a preliminary finite-element model. Theproperties of vibration modes with prevailing amplitudes along theradial and circumferential direction of the viaduct were describedwith poor precision. This disagreement required the calibration ofthe finite-element model through a tuning procedure based on modaldata. In particular, the experience has shown that the dynamicbehavior of the viaduct is strongly influenced by the mechanicalproperties of the bearing devices supporting the decksuperstructures. The calibrated finite-element model can be usedas baseline model for future monitoring and condition assessmentprograms on this typology of infrastructures.