Vibration Monitoring of the Voigt Bridge using Wired and Wireless Monitoring Systems

Structural monitoring systems using wireless sensors have the potential to serve as low-cost alternatives to commercially available cable-based monitoring systems. This paper describes a wireless sensing prototype system specifically designed for structural monitoring applications. To validate the performance of the prototype system, a network of up to 20 wireless sensing units is installed on the Voigt Bridge located on the campus of the University of California, San Diego. The wireless sensor network is installed in about an hour for a short-term study of the bridge dynamic properties. Prior to the validation test, a permanent cable-based structural monitoring system has been installed. The acceleration response of the Voigt Bridge concrete box girder is recorded by both monitoring systems. Strong agreement from the data collected by the two systems is observed. The wireless sensing units are also programmed to locally process their measurement data in real-time using an embedded fast Fourier transform algorithm; Fourier response spectra are then wirelessly transmitted to the wireless network server. The measurements acquired using the wireless monitoring system are shown to be accurate for precise determination of the primary modal frequencies and operating deflection shapes of the bridge deck.