Uncertainty propagation in bridge flutter analysis

This paper presents a method to approach flutter instability in a probabilistic way and to calculate the critical wind speed, starting from the probability distribution 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 stochastic 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 well-behaving and particularly critical cases 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.