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Application of Existing Damage Detection Measures for Long-Span Cable Stayed Bridges under Multiple Support Excitations

Bakhshizadeh, Arezoo | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47120 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayyaz
  7. Abstract:
  8. Damage and collapse in structural systems due to unexpected structural loading that seems to be inevitable sometimes leads to financial and human losses, despite of all safety measures considered for the system. Therefore, using structural health monitoring methods in order to estimate structural damages and preventing structural collapse, have drawn a lot of attention. In this study, the performance of different system identification methods such as mode shape curvature method, energy method, etc., to extract the dynamic properties of a cable-stayed bridge is examined. One of the main features of this study is to consider the seismic response of the bridge under multiple support excitations for identifying the extent of the inflicted damage to the bridge caused by strong ground motion. In this study, Abaqus software is used for modeling and dynamic analysis of the considered cable stayed bridge. Also, the obtained results were used for identification of the dynamic characteristics of the bridge using “Matlab” program. The artificial records have been generated for determined distances and are based on spectral density and on incoherent functions, respectively. In addition, the effect of wave propagation, velocity and coherency of the seismic input waves are considered. The velocity of 700 m/s is considered in the analysis as the soil shear wave velocity. Also, the peak ground acceleration was scaled 0.5g was assumed. Dynamic analysis has been done by applying displacement time history to the supports of the bridge. The results indicate that the strain response method was very efficient for detecting damages. Knowing that the dynamic characteristics of the bridge is continuously changing while the main supports of the bridge are undergoing different motions during the earthquake event, the results of modal analysis of bridge under extreme displacements of the supports were used for damage estimations of the bridge
  9. Keywords:
  10. Damage Detection ; Multiple Support Excitations ; Mode Shape Curvature Method ; Energy Index ; Spectral Density Function ; Incoherent Function

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