Modal Analysis of Reinforced Concrete Bridges with Multiple Neoprene Bearings

The study presents the modal analysis of a bridge made of reinforced concrete beams subjected to external dynamic actions from road traffic and/or seismic movements. The bridge is modeled as a 6DOF solid body with viscoelastic bearings that schematize the neoprene support devices. The case study presents the modal analysis of the bridge on the A3 Transilvania Highway Romania (between Târgu Mureș and Cluj Napoca, subsection 2B, Săvădisla, Km 29 + 602.75 ↔ Km 29 + 801.25), modeled as a solid body with neoprene bearings devices 300 × 500 × 81 mm, for which they were determined and analyzed the modal vibration modes. A series of experimental results obtained from “in-situ” dynamic tests are presented, using the virtual instrumentation technique; the experimental determinations were carried on Săvădisla bridge. A total numer of 3 × 16 tests were performed in order to determine the response of the bridge structure to dynamic traffic forces (shocks, vibrations). A truck with a total mass of 41 tons generated the shocks by passing over the standardized obstacles chemically fixed on the surface of the bridge; in total, 16 sets of measurements were performed, differentiated by the following parameters: v = 10–50 km/h, h = 40–80 mm, with/without traction.