By separating the stiff shear walls of the structural core of a building from the more flexible column/beam/slab structure two independent structures with markedly different dynamic properties are formed. By introducing damping elements between the two, energy is absorbed during earthquakes, giving consider- ably improved response characteristics. A ten storey office structure incorporating dampers in this fashion is studied by time history analysis, using five simulated earthquakes. Dampers are provided at each floor level. The analysis treats the damping as hysteretic, based on the type described by Kelly (1972). Significant reductions in structural response are achieved by this means.