@Article{sdhm.2008.004.117,
AUTHOR = {B.K.Raghuprasad,  N.Lakshmanan,  N.Gopalakrishnan,  K.Muthumani},
TITLE = {Sensitivity of Eigen Value to Damage and Its Identification},
JOURNAL = {Structural Durability \& Health Monitoring},
VOLUME = {4},
YEAR = {2008},
NUMBER = {3},
PAGES = {117--144},
URL = {http://www.techscience.com/sdhm/v4n3/35007},
ISSN = {1930-2991},
ABSTRACT = {The reduction in natural frequencies, however small, of a civil engineering structure, is the first and the easiest method of estimating its impending damage. As a first level screening for health-monitoring, information on the frequency reduction of a few fundamental modes can be used to estimate the positions and the magnitude of damage in a smeared fashion. The paper presents the Eigen value sensitivity equations, derived from first-order perturbation technique, for typical infra-structural systems like a simply supported bridge girder, modelled as a beam, an end-bearing pile, modelled as an axial rod and a simply supported plate as a continuum dynamic system. A discrete structure, like a building frame is solved for damage using Eigen-sensitivity derived by a computational model. Lastly, neural network based damage identification is also demonstrated for a simply supported bridge beam, where the known-pairs of damage-frequency vector is used to train a neural network. The performance of these methods under the influence of measurement error is outlined. It is hoped that the developed method could be integrated in a typical infra-structural management program, such that magnitudes of damage and their positions can be obtained using acquired natural frequencies, synthesised from the excited/ambient vibration signatures.},
DOI = {10.3970/sdhm.2008.004.117}
}