Indirect bridge modal identification enhanced by iterative vehicle response demodulation

Abstract

This paper introduces a novel indirect bridge modal identification framework for extracting higher-mode bridge modal parameters. The method involves processing the vehicle response using a newly proposed iterative vehicle response demodulation technique, which separates multi-component vehicle responses while preserving the physical meaning of variables. This property is crucial for ensuring accurate and robust modal identification from vehicle responses. The feasibility of this approach is initially tested through the analysis of vehicle responses generated by numerical simulations. This analysis includes a detailed parametric study and discussions on various bridge conditions and types. Subsequently, the same methodology is applied to an experimental bridge, where structural modal parameters are extracted from the measured responses of a passing instrumented vehicle. The key contributions of this study include the development of the iterative vehicle response demodulation formulation and the ability of this method to identify modal parameters using fewer processing steps compared to conventional indirect identification methods. Results from both numerical simulations and experimental tests demonstrate that the iterative demodulation method can effectively extract higher-mode bridge modal parameters, validating the proposed framework's effectiveness.