Measurement uncertainty in operational modal analysis of a civil structure

Many structural health monitoring techniques are based on modal parameter values, meaning that these values are monitored and a change may indicate a structure evolution and possibly an ongoing damage situation. This paper is intended to estimate the dispersion associated to the modal parameter estimation algorithm. This dispersion, due to the signal processing method, represents a threshold under which it is not possible to recognize a modal parameter change linked to a structural modification. The research has been carried out by developing a modal model of one of the G. Meazza Stadium stands in Milano, which represents the test case. The numerical results obtained thanks to the Monte Carlo method have been then compared to experimental data collected at the stadium and post-processed