Modal analysis based on cross-correlation data
Heung‐Fai Lam, Jia-Hua Yang · 2022
This chapter presents an efficient method for identifying modal parameters of engineering structures under operational conditions based on cross-correlation data (Beck 1979; Beck and Jennings 1980; Werner et al. 1987; Au et al. 2005; Yang et al. 2019; Lam et al. 2019 ). The dynamic system of a structure is constructed using modal parameters (e.g., natural frequencies, damping ratios, mode shapes, and modal initial displacements and velocities) so that cross-correlations of dynamic responses can be formulated in terms of modal parameters. Identification of modal parameters is formulated as an optimization problem, where the difference between the experimental and model-predicted cross-correlations is minimized. A fast optimization method that iterates among different modes is proposed. Only a two-dimensional optimization problem needs to be solved for each mode, and direct optimization for high-dimensional mode shape vectors is not required. The proposed method is demonstrated through modal analysis of a full-scale footbridge.