Reliability of bridge deck flutter derivative measurements in wind tunnel tests

The reliability of flutter derivative measurements in wind tunnel is investigated considering the actual scatter of data points in smooth and turbulent flow. Two rectangular cylinders with different width-to-depth ratios tested in wind tunnel were taken into consideration in this study. Considering the flutter derivatives at each reduced velocity as independent Normal-distributed random variables, it was possible to realize Monte Carlo simulations of the functions and to compute some statistics of the flutter instability limits. The results seem to suggest a fairly good statistical behavior of flutter speed and coupling frequency, being mean values very close to the deterministic ones and relatively small dispersion. Nevertheless this conclusion cannot be gener-alized because of a completely different and instable behavior observed in one case.