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Structural Engineering and Mechanics
  Volume 35, Number 6, August20 2010, pages 735-758
DOI: http://dx.doi.org/10.12989/sem.2010.35.6.735
 


Comparative study on damage identification from Iso-Eigen-Value-Change contours and smeared damage model
N. Lakshmanan, B.K. Raghuprasad, N. Gopalakrishnan, R. Sreekala and G.V. Rama Rao

 
Abstract
    The paper proposes two methodologies for damage identification from measured natural frequencies of a contiguously damaged reinforced concrete beam, idealised with distributed damage model. The first method identifies damage from Iso-Eigen-Value-Change contours, plotted between pairs of different frequencies. The performance of the method is checked for a wide variation of damage positions and extents. The method is also extended to a discrete structure in the form of a five-storied shear building and the simplicity of the method is demonstrated. The second method is through smeared damage model, where the damage is assumed constant for different segments of the beam and the lengths and centres of these segments are the known inputs. First-order perturbation method is used to derive the relevant expressions. Both these methods are based on distributed damage models and have been checked with experimental program on simply supported reinforced concrete beams, subjected to different stages of symmetric and un-symmetric damages. The results of the experiments are encouraging and show that both the methods can be adopted together in a damage identification scenario.
 
Key Words
    damage identification; Iso-eigen-change; smeared damage model.
 
Address
N. Lakshmanan: Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India
B.K. Raghuprasad: Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India
N. Gopalakrishnan: Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India
R. Sreekala: Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India
G.V. Rama Rao: Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India
 

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