Structural infrasound from a barge collision with the Mississippi River Bridge

The Mississippi River Bridge in Vicksburg MS is a 7 span cantilever bridge 3389 feet long by 68.5 ft wide and is part of the Interstate-20 corridor. On 23 March 2011 around 1:30 pm, a barge moving downstream struck a pier of the bridge. Infrasound stations located at the Waterways Experiment Station (WES) detected the impact. There are indications from the infrasound signatures that infrasound was radiated from the bridge and also from disturbances on the surface of the water (waves or eddies) that resulted from the collision. Finite Element (FE) models of the bridge and pier were developed to simulate the response of the bridge due to the barge impact. It was possible to identify those portions of the infrasound signature produced by vibration of the bridge deck. A synopsis of the accident will be presented along with the recorded infrasound signatures. Results from the dynamic structural model of the bridge will be discussed and related to the infrasound signature.