Investigating the Performance of a Wide-Deck Bridge

The paper focuses on a 3-span viaduct recently erected about 16 km far from Milan, Italy. The bridge superstructure consists of a steel-concrete composite girder supported by two RC piers and abutments. The bridge girder is formed by a central span of 35 m and two side spans of 32 m, so that the total bridge length equals 99 m. The bridge deck was designed to carry five traffic lanes, two emergency lanes, and one sidewalk. Hence, the bridge deck is 33.5 m wide, with the ratio between span length and deck width being approximately equal to one. At the commissioning phase, the viaduct deck was instrumented through a set of accelerometers to perform ambient vibration tests. Moreover, FE modelling of the viaduct, validated via Operational Modal Analysis, was performed to predict the static deflections of the deck during proof load testing. Both experimental and numerical dynamic characteristics involve the sequence of one bending mode, two torsion modes and four "plate" modes due to the large deck width. The paper showcases the dynamic behaviour of thewide-deck bridge and discusses the advantages of combining dynamic and static tests to validate FE models.