Output-only Based Identification of Modal Parameters of Linear and Nonlinear Structures by Wavelet Transform

In recent years, the methods of integrity monitoring of civil structures and mechanical ones, such as damage detection, fatigue analysis and risk-based management structures, have been receiving considerable interest from various fields of science and engineering. This work uses a mathematical tool for calculation and for a relatively new signal processing, in which uses a time-frequency analysis that provides more detailed information about non-stationary signals. We are talking about the Wavelet Transform. First, the Continuous Wavelet Transform is used to identify the modal parameters such as natural frequencies and damping rates, of a linear structure with four degrees of freedom. After that, this method is tested on a non-linear structure that represents a 20 floor building, proposed in the literature. A theoretical explanation of the methodology and an example of a simple application are also presented in order to understand the efficiency of the technique in the identification of modal parameters of structures.