Ambient Vibration Tests of Two Prestressed Reinforced Concrete Highway Overpasses

The safety assessment and monitoring of existing bridges is an important issue, on which researchers, engineers and institutions are working to find the best investigation strategies, optimizing the limited resources available. Ambient vibration test can be combined with other traditional tests, such as static load tests, to obtain more information about structural features and identify any deterioration phenomena. In this study, two prestressed reinforced concrete bridge are investigated both with static load test and with ambient vibration test. Objective of the tests was to determine, for each of the two bridges, vibration frequencies, mode shapes and damping-ratios. A preliminary FE model was update using both experimental modal characteristics and displacement values obtained from static load test, to estimate the stiffness of the decks and compare it with the theoretical one.