Comparison Of Several Damage Identification Methods Of Structure Based On Ambient Excitation

Structural health diagnosis is the hot topic for research in the field of civil engineering. Structural damage to explore and use the information to identify some ways, the location of the structural damage was to find the basic procedure of structure health diagnostic.This paper studies the following: Two frequency domain modal identification and four time domain methods of modal identification based on ambient excitation carried through damage recognition to three steel-frame models, and the results also identified a comparison. Location of structural damage was judged by coordinate modal assurance criteria and modal flexibility difference.Completed the major work as follows:1. A three-story steel frame structural finite element modeling was built with ANSYS. Damage was simulated by changing the elasticity modulus. Modal analysis (frequency and vibration mode) and dynamic response analysis is done at healthy condition and three damage condition.2. Acceleration response of the measuring points was gained by the structure. Then modal analysis was done by peak picking technique and frequency domain decomposition. The Structural damage was judged by identification result.3. Displacement response of the measuring points was gained by the structure. Then modal analysis was done by time series analysis and stochastic subspace identification. The structural damage was judged by identification result.4. Free vibration signal of the measuring points were gained by random decrement technique. Then modal analysis was done by LSCE method. The structural damage was judged by identification result.5. The cross-correlation function of the measuring points relative to reference point was gained by the natural excitation technique, taken as impulse response functions. Then modal analysis was done by ITD method. The structural damage was judged by identification result.6. The location of structural damage was judged by the injury index of the Coordinate Modal Assurance Criteria and modal flexibility.7. Compared the identified results of six methods based ambient excitation and two injury indexes.