Modal analysis

Modal

Control (management)

Engineering

Polymer chemistry

Biology

Identification (biology)

Materials science

Bridge (graph theory)

Component (thermodynamics)

Vibration

Computer science

Botany

Acoustics

Modal testing

Modal analysis using FEM

Thermodynamics

Physics

Internal medicine

Artificial intelligence

Composite material

Structural engineering

Medicine

Control theory (sociology)

Journal of Engineering Mechanics

In the dynamic characteristic analysis of high-speed railway bridges, free-vibration responses after a train passes are valuable for modal identification. However, distinguishing between free- and forced-vibration segments requires user intervention, which hinders the reliable and continuous identification of modal parameters, thereby impeding the vibration-based structural state assessment. This paper proposes a free-vibration detection technique whose basis is that the envelope function of each modal component decomposed from the free-vibration data decays exponentially. To extract the modal component adaptively, iterative variational mode decomposition is proposed where the signal is iteratively decomposed into two components until a single-degree-of-freedom component is obtained. Subsequently, the estimated free-vibration data are adopted to identify the modal parameters by the eigensystem realization algorithm with data correlation. A numerical simulation illustrates that the proposed method can provide the optimal free-vibration data for modal analysis. To verify the effectiveness of the proposed method in practice, the accelerations of the railway bridge during the passage of a train are analyzed. The modes can be identified from the estimated free-vibration data but not from the combination of forced- and free-vibration data, which indicates that the separation of forced and free vibration is necessary and can be achieved by the proposed method.

Modal Identification of High-Speed Railway Bridges through Free-Vibration Detection