GLOBAL SCALING OF OMA MODES SHAPES WITH THE OMAH METHOD

Mode shapes obtained by operational modal analysis lack information about the modal scaling (or, modal mass). In many cases, this does not pose any limitation, but in certain cases, for example for some structural health monitoring methods, and computational model validation, a scaled modal model is important. We recently presented a new approach for scaling OMA modal models using harmonic excitation, called the OMAH method, and showed that this method is robust and reliable. The method relied, however, on excitation and response measurements in one measurement point for each mode. In the present paper, we extend the numerical processing of the measurements, taking many measurements across the structure into account for the scaling. This is analog to using so-called global parameter estimation in the classical experimental modal analysis (EMA) methods. We also propose an extension of the method to the case of multiple-reference analysis, which can be utilized when there is no single excitation point for which all modes have large mode shape coefficients.