Uncertainty quantification of the Modal Assurance Criterion in operational modal analysis

The Modal Assurance Criterion (MAC) is a modal indicator designed to decide whether the mode shapes used in its computation are corresponding same mode. During structural monitoring, it can be applied evaluate changes shapes. When estimated from measurement data, MAC inherits their statistical properties, thus afflicted with uncertainty. evaluation of this uncertainty particularly relevant when estimate close 1, where 1 indicates equal In assess after early damage. While framework for quantification parameters well-known and developed context subspace-based system identification methods, has not been yet. A particular challenge characterization boundedness interval between 0 1. paper shown that yields two different distributions estimates. computed estimates inside (0,1), Gaussian approximation distribution obtained. shapes, resultant classical inadequate. case linked quadratic form whose approximated by scaled shifted ?2 distribution. For both cases, bounds related established. proposed frameworks validated extensive Monte Carlo simulations then shape due damage during monitoring S101 Bridge.