Structural Health Monitoring of Bridges using both local vibrations and structure-borne acoustic waves

For the structural health monitoring of bridges, we investigated different acceleration signals excited by passing vehicles. By driving onto or off the bridge thereby crossing the expansion joint impulse like signals are excited by every passing axle. These signals travel as structure-borne acoustic waves through the whole bridge. The driving over the bridge between the joints also excites waves, but with limited ranges. Both signal types carry information about the physical properties of the bridge. Both signal types have been investigated for their reproducibility. In both cases, signals excited by trucks turned out to be more reproducible then signals excited by cars. Finally, the velocity of passing vehicles could easily be estimated from a Doppler shift in the limited-range signals.