Ambient vibration testing of historic steel-composite bridge, the E. Torroja Bridge, for structural identification and finite element model updating

Abstract

The E. Torroja Bridge is a steel-composite bridge which combines inverted steel arch trusses with a concrete deck. This bridge crosses the Guadalquivir River in the small town of Posadas, 30 km far from Córdoba, Spain. It was E. Torroja, the renowned civil engineer who designed and built it until its inauguration in 1951 with an original deck 7 m width. Nevertheless, in 1995 it was remodeled by the author’s grandson, José Antonio Torroja, who raised the width of the deck to 11 m and added two new inverted steel arches beside the original ones. In order to assess the structural health condition of the bridge, ambient vibration tests were carried out in June 2014. The assessment procedures include full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modelling and dynamic-based identification of the uncertain structural parameters. All the changes experienced by the structure suppose a high level of uncertainty, which affects material’s properties and structural schemes in relation to deterioration processes and the structural modifications. Hence, a rigorous updating process in the finite element model was necessary to approach the experimental data with the numeric calculations.