In this paper we study a problem of passive nonlinear targeted energy transfer between a two degrees of freedom long span bridge model prone to coupled flutter and a single degree of freedom nonlinear energy sink (NES). This study is mainly analytical and use complexification methods, multiple scales expansions and exploits also the concept of limiting phase trajectories (LPTs). The system is studied under 1:1:1 nonlinear resonance involved in targeted energy transfer mechanisms. Several behaviors that suppress aeroelastic instability are identified. We show that analytical calculations permit to design a NES able to efficiently control the aeroelastic instability of the bridge. Numerical simulations are performed and good agreement with analytical predictions is observed. It results that the concept of limiting phase trajectories (LPT) allows formulating adequately the problem of intensive energy transfer from a bridge to a nonlinear energy sink.