Damage characterization through nonlinear analysis of transient vibrations
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abstract
The basic notion behind vibration-based structural health monitoring is that changes in the physical properties of the structure such as mass, flexibility and stiffness vary the structural response characteristics such as the natural frequencies, mode shapes and damping ratio. Because of their dependence on environmental and other conditions than on damage, natural frequencies alone may not be sensitive enough to be used as parameters for damage characterization. This work aims to present specific nonlinear parameters and show their relatively higher sensitivity, in comparison to natural frequencies, to damage conditions. Because ambient vibrations can be transient and nonstationary, wavelet-based higher-order spectral moments are proposed as the tools to derive these parameters. As a numerical example, the higher sensitivity of the nonlinear parameters is demonstrated through the analysis of the damped response of a nonlinear system. The same nonlinear parameters are derived from vibration measurements of an eight-span simply supported bridge with a continuous slab over the SidiBouAli river in Tunisia to show that these parameters can be derived from full scale tests.
