Understanding the dynamic behavior of complex structures such as long-span bridges requires dense deployment of
sensors. Traditional wired sensor systems are generally expensive and time-consuming to install due to cabling. With
wireless communication and on-board computation capabilities, wireless smart sensor networks have the advantages of
being low cost, easy to deploy and maintain and therefore facilitate dense instrumentation for structural health
monitoring. A long-term monitoring project was recently carried out for a cable-stayed bridge in South Korea with a
dense array of 113 smart sensors, which feature the world’s largest wireless smart sensor network for civil structural
monitoring. This paper presents a comprehensive statistical analysis of the modal properties including natural
frequencies, damping ratios and mode shapes of the monitored cable-stayed bridge. Data analyzed in this paper is
composed of structural vibration signals monitored during a 12-month period under ambient excitations. The correlation
between environmental temperature and the modal frequencies is also investigated. The results showed the long-term
statistical structural behavior of the bridge, which serves as the basis for Bayesian statistical updating for the numerical
model.
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