Vibration Testing of a Steel Girder Bridge using Cabled and Wireless Sensors

Being able to significantly reduce system installation time and cost, wireless sensing technology has attracted much interest in the structural health monitoring (SHM) community. This paper reports the field application of a wireless sensing system on a 4-span highway bridge located in Wayne, New Jersey in the US. Bridge vibration due to traffic and ambient excitation is measured. To enhance the signal-to-noise ratio, a low-noise high-gain signal conditioning module is developed for the wireless sensing system. Nineteen wireless and nineteen cabled accelerometers are first installed along the sidewalk of two neighboring bridge spans. The performance of the wireless sensing system is compared with the high-precision cabled sensing system. In the next series of testing, sixteen wireless accelerometers are installed under the deck of another bridge span, forming a 4× 4 array. Operating deflection analysis is successfully conducted using the wireless measurement of traffic and ambient vibrations. Keyword: wireless sensing, structural health monitoring (SHM), signal conditioning, operating deflection analysis, ambient vibration.