Abbas parvin - Master of science, Islamic Azad University, Bushehr,
Mahmood seraji - Assistant professor, Islamic Azad University, Bushehr
Mohamad vaghefi - Assistant professor, persian gulf University, Bushehr

In order to illustrate the effect of damping on the response of a base-isolated building, a large investigation is made. It consists in a parametric study which takes into account the progressive variation of the damping ratio (10% to 30%) under different nature of seismic excitations (near and far field). A time history analysis is used to determine a response of the structure represented in this case by terms of relative isplacements and inter-stories drift at various levels of the building. the results show that the efficiency of the isolator increases with the assumed damping ratio, provided that this latter is less or equal to 20%. Beyond this value, the isolator becomes less convenient

Damping; base isolation; LRB; time history