Selection of reference coordinates using effective independence technique in operational modal testing of structures

Conventional modal testing of large structures is always associated with difficulties in artificial excitation of the structure. Operational Modal Analysis (OMA) is one approach to overcome the excitation problem. In OMA only the responses are measured and the structure is excited by ambient forces. For large structures the simultaneous measurement of responses in all selected points is usually impossible due to not having enough available accelerometers or measurement channels. Therefore، the structure is tested in several steps. As a result، some reference points should be selected to correlate all of the measurements. In this article a new criterion is introduced for selection of reference points based on finite element model of structure. A beam is used for numerical validation of the method. A steel beam is also used for experimental case study. Both numerical and experimental results demonstrate the effectiveness of this criterion.