A Study On Vibration-Based Damage Detection Methods For Bridge Structures

Structural performance deterioration will inevitably occur because of kinds of factors such as environmental force, seismic actions et al. Particularly for those bridges located in important traffic lines in their service life. Therefore efforts trying to estimate damage status of the structure and to ensure safety are highlighted in structural engineering research. Those procedures are the so-called Damage Detection and Structural Health Monitoring (SHM) . In recent 30 years, researchers come from civil, aerospace and mechanical engineering communities have been exploring kinds of damage assessment methods for whole structure. The basic idea of these efforts is through measuring and analyzing vibration response signals of the structure to find changes of dynamic behavior so as to realize a quick, automatic and overall damage detection, damage localization and damage quantification.In this dissertation main theories and methods of the vibration-based structural damage diagnosis are discussed. Damage diagnosis method based on the FEM modification and the measured structural dynamic behavior as well as the Damage Index Methods ( DIM ) are particularly investigated. On the base of deep understanding the advantages and disadvantages of different methods three kinds of vibration-based methods are proposed and are validated by various examples.FEM and measured structural vibration characteristics based damage diagnosis method are provided with rigorous theory and has great diagnosis potential. However, for a large structure with great amount of computation and with considerable number of degree of freedom DOF are the fatal disadvantages to this kind of method. It is evident that updating for all parameters is unpractical. A kind of approach is to update those parameters and elements with relative large errors or significant impact to structural dynamic behavior. In other words, to develop a complex procedure which combines several structural damage diagnosis methods (SDDM) to take use of merits of different SDDM will be a reasonable and effective way. A new FEM-based three steps damage diagnosis procedure is proposed. For a civil structure consider the features that damage diagnosis is generally at component or element level. The procedure includes damage detection, damage element selection & search and iterative quantity at element level. First, measured dynamic characteristic and FEM model of the structure are used to determine mode residual force. Second,...