Modal Parameter Identification Method for Structural Health Monitoring Benchmark Model

Abstract

Structural modal parameters can be identified using both output responses and input excitations or only using output responses of structures. When the input excitations are known, some frequency response functions (FRF) can be obtained and further used to accurately identify the modal frequencies and mode shapes of structures, but the identified modal damping ratio is often lack of reliability. Under ambient excitations, the peak picking method (PP) is often used to quickly identify the modal parameters of structures, but some vibration modes are missed sometimes, particularly when the dense modes or subjective errors may appear around the peaks picked. Modal parameters can be identified using the stochastic subspace identification method (SSI) based on statistical data, however, the SSI method easily produces false modes in practice. In order to compensate the deficiencies of SSI method, the PP and the SSI methods are combined to identify the modal parameters of the benchmark structure which proposed by the International Association for Structure Control and the task group of American Society Civil Engineers (IASC-ASCE) in this paper. The illustrated results show that this combination method can accurately identify the modal parameters of the benchmark structure with some application prospects.