AbstractA novel system decoupling approach (SDA) that enables three degree-of-freedom (3-DOF) bridge flutter analysis is proposed in this study to simultaneously investigate the relationships between modal parameters and 18 flutter derivatives. Based on the incentive-feedback mechanisms, the aerodynamic coupled system is conveniently decoupled in an iterative solution. Based on the SDA, it is unnecessary to simultaneously calculate all multiple frequencies for determining modal parameters and eventually quantifying critical flutter wind velocity. The efficacy and accuracy of the SDA is verified using a numerical example of thin flat plate. The coupling effects among three DOFs and influence of 18 flutter derivatives on flutter performance are quantified using the newly proposed method. The flutter mechanisms of thin flat plate and bluff deck section of the Akashi Kaikyo Suspension Bridge are numerically examined, and both difference and common grounds for two typical flutter phenomena are summarized. The ...