Propagazione dell’incertezza dai coefficienti aeroelastici alla velocità critica di flutter di un ponte

This paper presents a method to approach flutter instability in a probabilistic way and to calculate the probability distribution of the critical wind speed, starting from that of the flutter derivatives. Uncertainty propagation in the flutter problem is studied and the results are considered in the framework of the performance-based design. The statistical properties of experimental flutter derivatives were investigated with ad-hoc wind tunnel tests performed on a bridge deck model of common geometry. The probability distribution of the flutter critical wind speed can be analytically calculated if a simplified approach to flutter is followed. By contrast, Monte Carlo methods have to be utilized in the general case. Application examples are presented and both a well-behaving and a particularly critical case of uncertainty propagation are discussed. Finally, the effect of correlation between flutter derivatives is studied, observing that it plays a non-negligible role in the definition of the probability distribution of the flutter wind speed.