Dynamic Tests of a Railway Viaduct

This paper refers to the dynamic tests of a railway viaduct that were performed shortly after the end of its construction as part of reception tests that included also static load tests. The dynamic tests consisted in the measurement of railway traffic induced vibrations and in ambient vibration measurements. The paper presents, therefore, the results obtained in those tests, both in terms of levels of vibration measured during the passage of trains and also in what concerns the identified dynamic properties. For the modal identification, two procedures were used, the enhanced frequency domain decomposition method (EFDD) applied to the ambient vibration tests data and the covariance driven stochastic subspace identification method (SSI-COV) applied to the free vibrations measured immediately after a train had crossed the viaduct. The results obtained with the two identification procedures are in good agreement, but with larger damping values evaluated from the free vibration records. The identified dynamic characteristics were also compared with the frequencies and mode shapes computed with finite element models and a good agreement was obtained between the experimental and model results.