In view of the development of heavy timber seismic-resistant structures, in the context of modern seismic design approach, a possible solution is to allow the timber structure to dissipate a part of the seismic energy. Since timber is a material with an elastic-fragile behaviour, the dissipative function should be delegated to connections, through plastic deformation of steel connectors. However, joints are primary structural elements, with a crucial role in bearing the design loads. Therefore, the role of seismic energy dissipation should be conveniently assumed by ad hoc devices. In this context, the paper deals with the application of fluid viscous dampers (FVD) to timber frames: FVDs dissipate seismic energy, while timber elements and steel connections remain elastic. Specifically, 2D single-storey structures with dissipative bracing systems, equipped with FVDs, in different configurations, are studied, assuming several rates of possible dampings. Non-linear dynamic time history analyses are performed (SAP2000, v18). Results are discussed showing significant reduction of the structural mass compared to the non-dissipative ones, recentering capability of the structures, high dissipative capacity, simpler elastic connections. The reduction of production and maintenance costs follows. All these involve the efficiency of the structural performance and sustainability under earthquakes.