Abstract: Vibrations due to natural dynamic loads generated by earthquake. The reducing of structural vibrations occurs by adding a mechanical system that is installed in a structure called Dampers .In this paper, the vibration control of multi degree of freedom (MDOF) buildings connected with selected types of dampers due to earthquake effect is studied. The application of Viscous and Semi active variable friction (SAVFD) damper for response control of seismically excited building is evaluated. Both dampers effectiveness is investigated in terms of the reduction of structural responses (displacements and accelerations) of the connected to building. The optimum number and the location of dampers are decided by the optimization procedure.