In this study, the variations of optimal damper placement using different objective functions are presented. Instead of the usual choice of transfer function amplitude of the top displacement of the structure, the transfer function amplitude of the base shear force evaluated at the undamped fundamental natural frequency of the structure is chosen as an objective function. In the optimization procedure, the damping coefficients of the added dampers are treated as design variables. An active constraint on the sum of the damping coefficients of added dampers and the upper and lower bounds for each damper are taken into consideration. The new objective function based on transfer function amplitude of the base shear force is compared with the transfer function amplitudes of top displacement. The response of the structure is investigated for both of the objective functions in terms of the transfer function. The time history analysis is performed using the Kobe earthquake ground motion records to demonstrate the validity of the proposed design method. The results of the numerical procedure show that the proposed procedure based on the transfer function of the base shear force can also be beneficial in the rehabilitation of seismic response of the structures. (c) 2006 Elsevier Ltd. All rights reserved.