Effects of errors in flutter derivatives on the wind-induced response of cable-supported bridges

This dissertation discusses the development and implementation of a methodology for the buffeting response of cable-supported bridges, including uncertainty in the aeroelastic input (i.e., flutter derivatives, FDs). Flutter derivatives are the most important part of the loading and are estimated in a wind tunnel experiment.;A second order polynomial model ("model curve") for the flutter derivatives is proposed. The coefficients of this polynomial are random variables, whose probability distribution is conditional on the reduced wind speed. For computational reasons in subsequent analysis, however, this dependency is neglected and the probability of these random variables is treated as independent of the reduced wind speed. For analysis purposes the first- and second-order statistics are estimated from experiments, treating all the wind speed data as part of the same population. Wind tunnel experiments are conducted at Northeastern University and a section model of a truss-type bridge deck is used.;The simplified polynomial model for the FDs, including the second order description of its variability, is employed in the derivation of the probability of the onset of flutter using Monte-Carlo (MC) simulations.;The simplified stochastic "model curves" for FDs are used to estimate the buffeting bridge response. In the standard approach the result of the buffeting analysis is the value of the RMS dynamic response at a given wind speed. In the proposed probabilistic setting one estimates the probability that a given threshold for the variance of the response is exceeded. This probability is later used, together with information on the probability of the wind velocity at a given site, to predict the expected value of the loss function due to the buffeting response of a 1200-meter suspension bridge (a function proportional to the cost associated with interventions needed to ensure safety).