Techno Press
Techno Press

Smart Structures and Systems   Volume 3, Number 3, July 2007, pages 281-298
Structural performance evaluation of a steel-plate girder bridge using ambient acceleration measurements
Jin-Hak Yi, Soojin Cho, Ki-Young Koo, Chung-Bang Yun, Jeong-Tae Kim, Chang-Geun Lee and Won-Tae Lee

Abstract     [Full Text]
    The load carrying capacity of a bridge needs to be properly assessed to operate the bridge safely and maintain it efficiently. For the evaluation of load carrying capacity considering the current state of a bridge, static and quasi-static loading tests with weight-controlled heavy trucks have been conventionally utilized. In these tests, the deflection (or strain) of the structural members loaded by the controlled vehicles are measured and analyzed. Using the measured data, deflection (or strain) correction factor and impact correction factor are calculated. These correction factors are used in the enhancement of the load carrying capacity of a bridge, reflecting the real state of a bridge. However, full or partial control of the traffic during the tests and difficulties during the installment of displacement transducers or strain gauges may cause not only inconvenience to the traffic but also the increase of the logistics cost and time. To overcome these difficulties, an alternative method is proposed using an excited response part of full measured ambient acceleration data by ordinary traffic on a bridge without traffic control. Based on the modal properties extracted from the ambient vibration data, the initial finite element (FE) model of a bridge can be updated to represent the current real state of a bridge. Using the updated FE model, the deflection of a bridge akin to the real value can be easily obtained without measuring the real deflection. Impact factors are obtained from pseudo-deflection, which is obtained by double-integration of the acceleration data with removal of the linear components on the acceleration data. For validation, a series of tests were carried out on a steel plate-girder bridge of an expressway in Korea in four different seasons, and the evaluated load carrying capacities of the bridge by the proposed method are compared with the result obtained by the conventional load test method.
Key Words
    load carrying capacity; ambient vibration test; modal identification; model updating; deflection correction factor; impact factor; steel plate girder bridge.
Jin-Hak Yi; Coastal Engineering Research Department, Korea Ocean Research and Development Institute,
Sa-2-Dong, Ansan, Gyeonggi, 426-744, Korea
Soojin Cho, Ki-Young Koo, and Chung-Bang Yun; Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology,
Guseong-Dong, Yuseong-Gu, Daejeon, 305-701, Korea
Jeong-Tae Kim; Dept. of Ocean Engineering, Pukyong National University, Busan, 608-737, Korea
Chang-Geun Lee and Won-Tae Lee; Structural Division, Korea Highway Corporation, Hwasung, Gyeonggi, Korea

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