Serviceability Performance Analysis of Concrete Box Girder Bridges Under Traffic-Induced Vibrations by Structural Health Monitoring: A Case Study

The perceptible vibration of concrete box girders under traffic loads is an important topic in existing bridges, on which vehicle movement often cause vibrations too strong from the viewpoints of travelers. In this paper, the results of an extensive program of full-scale ambient vibration tests involving a 380 m concrete box girder bridge, the Cannavino bridge in Italy, are presented. The human safety assessment procedure of the bridge includes ambient vibration testing, identification of modal parameters from ambient vibration data, comparison with a detailed finite element modeling as validation of experimental measurements, comparison of peak accelerations to reference values from technical standards/literature in order to estimate the vibration level, and evaluation of safety by the use of histograms. A total of nine modal frequencies are identified for the deck structure within the frequency range of 0-10 Hz. The results of the ambient vibration survey are compared to the modal frequencies computed by a detailed three-dimensional finite element model of the bridge, obtaining a very good agreement. It emerges that a linear finite element model appears to be capable of capturing the dynamic behavior of concrete box girder bridges with very good accuracy. For each direction, experimental peak accelerations are compared to acceptable human levels available in technical standards/literature, showing that traffic loads mainly induce a vertical component of vibration on the bridge deck. Finally, the elaboration of histograms allows to assess that the bridge is exposed to clearly perceptible vertical vibrations, requiring the adoption of suitable vibration reduction devices.