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http://dx.doi.org/10.5394/KINPR.2008.32.3.215

Modal Analysis of a Large Truss for Structural Integrity  

Park, Soo-Yong (Division of Architecture and Ocean Space, Korea Maritime University)
Publication Information
Journal of Navigation and Port Research / v.32, no.3, 2008 , pp. 215-221 More about this Journal
Abstract
Dynamic characteristics of a structure, i.e., natural frequency and mode shape, have been widely using as an input data in the area of structural integrity or health monitoring which combined with the damage evaluation and structural system identification techniques. It is very difficult, however, to get those information by the conventional modal analysis method from large structures, such as the offshore structure or the long-span bridge, since the source of vibration is not available. In this paper, a method to obtain the frequencies and the mode shapes of a large span truss structure using only acceleration responses is studied. The calculation procedures to obtain acceleration responses and frequency response functions are provided utilizing a numerical model of the truss, and the process to extract natural frequencies and mode shapes from the modal analysis is cleary explained. The extracted mode shapes by proposed method are compared with those from eigenvalue analysis for the estimation of accuracy. The validity of the mode shapes is also demonstrated using an existing damage detection technique for the truss structure by simulated damage cases.
Keywords
large structure; modal analysis; natural frequency; mode shape; damage evaluation;
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