Extended Empirical Wavelet Transformation: Application to structural updating

Abstract

The determination of accurate global and local modal information is a crucial step for any structural model updating process. Existing modal extraction methods can extract global modal properties with a good degree of accuracy; however, they have difficulties extracting accurate local information under transient excitations. This work presents a novel method, called Extended Empirical Wavelet Transformation (EEWT), in which local and global modal information can be accurately obtained under transient excitations. A new objective function is proposed in this work, where the local and global information resulting from EEWT can be used inside an optimization problem to solve for structures’ unknown parameters and boundary coefficients using a minimum number of measurement points. The proposed EEWT modal extraction and updating schemes were experimentally implemented in two problems: a simply supported beam and a scaled model of a highway bridge with unknown boundary conditions. The results showed the capability of the proposed approaches to identify structural material properties and boundary coefficients of both systems under transient excitations. Comparison between the proposed method and three other well-known modal extraction methods illustrated the effectiveness of EEWT and showed how the resulting optimum points can be affected by the inaccuracy of the extracted modal information.