ductility of a shear wall designed for a future storey
 

ductility of a shear wall designed for a future storey
you are asked to design a four-storey building accounting for a future additional storey. you design the shear walls for five stories using a load reduction factor r=3.5 ( for example). the owner doesn’t know when that additional storey will be added. obviously, the shear walls are over designed and the expected ductility is less by the over-design ratio. how do you dead with such case?
thanks
malkobani,
from what i know, ductility is a measure of the ability of an element/structure to yield before failure.
even if the shear wall is over designed, the ductility may be similar: ratio of force/displacement_when_starts_yielding and force/displacement_when_fails.
if you design the structure to accommodate 5 storeys and the building will be only 4 storeys, i can not see any problem. the structure is stiffer and deflects less.