Modal Identification Method for Structures Subjected to Unmeasured Random Excitations

This paper describes a system identification technique useful in the practical case of structures subjected to unmeasured, stationary (ambient) excitations typically encountered in wind, ocean, and earthquake engineering. The method uses only the structural response records available and assumes a parametric form for the second-order statistics of the loading process. Both loading and structural modal parameters are extracted from the second-order statistics of the structural response, which are estimated from the response records (e.g., accelerograms). The proposed method was validated using extensive simulation tests, an example of which is presented here.