Field experiment of vibration characteristics of lightweight embankments converted from bridges using rigid polyurethane foam-filling under traffic load

The method of filling the lower space of a bridge with rigid polyurethane foam (RPU foam) to reduce the traffic load along with seismic reinforcement has rarely been applied to extend the life of bridges in Japan. This study evaluates the reinforcement effect and change in the vibration characteristics of a bridge converted into a lightweight embankment by RPU foam filling. A truck was driven on the bridge before and after the RPU foam filling. The vibration and strain of the slab were found to have reduced at the span center. When a traffic load was applied, the predominant frequency inside the RPU foam was ∼5 Hz, and long-period vibrations relative to the slab were confirmed. •The change in vibration of an RPU foam-filled bridge was studied.•RPU foam supports the upper structure at the center of the span.•RPU foam induces bridge member vibration.•RPU foam reduces the dominant frequency of the upper structure.