Response types and general stability conditions of linear aero-elastic system with two degrees-of-freedom

► Linear variant description of aeroelastic stability of bluff cross-sections is presented. ► Stability conditions are analyzed in frequency plane delimited by principal aero-elastic modes. ► The flutter and divergence conditions are identified as special cases of general description. ► Results can be used as phenomenological explanation of several experimentally observed effects. ► Application of this method to real bridges is presented and compared with other approaches.