The dynamic responses of a single-span

seven-storey frame on several construction sites were computed with the 2D finite element method for a few records of seismic waves to analyze the influence of SSI effects on the controlling efficiency of viscoelastic structures.The analyzed results indicate:（1）on sites of hard or slightly hard soils

the SSI effects clearly reduce the peak values of storey displacement so that

to make the actual displacement response of a structure satisfy the aseismic control objective based on the assumption of rigid ground

relatively few viscoelastic dampers are needed（compared with the number of viscoelastic dampers needed under the assumption of rigid ground） if the SSI effects are considered in the aseismic design;（2）the controlling efficiency of the viscoelastic dampers is closely related to the construction sites and the seismic waves;（3）compared with the rigid ground

the SSI effects reduce greatly the controlling efficiency of the viscoelastic dampers;and the softer the soils

the more the controlling efficiency will be reduced.Therefore

in real engineering designs

the SSI effectd should be taken into account to evaluate properly the controlling efficiency of the viscoelastic dampers.At the same time

the right type of dampers should be selected according to the site condition so that the prospective control objective can be achieved.