comparing the relation of stiffness -ductility in conventional and base isolated EBF frame

the main concern of designer engineers has been find good fitness relation between ductility and stiffness seismic resisting structures are insistent adequate during frequent cause the structures become over design in the elastic mode on one hand and to dissipate a large amount of energy under damaging earthquakes cause structure collapse in non elastic mode on the oither hand . one of the seismic resisting structures system which satisfies stiffness and energy dissipation requirements simultaneously is eccentrically braced frames.