Based on the experimental research of 48 reinforced concrete columns u
sing high strength and normal strength concrete under monotonic and cy
clic loading, the factors which affect the ductility, such as the conc
rete strength, axial load ratio, stirrup volume ratio, etc., are analy
zed. It can be concluded that the axial load ratio is the most importa
nt factor that affects the ductility. The axial load ratio limits and
relative stirrup volume ratio limits were proposed under the condition
of limited ductility (mu(Delta) greater than or equal to 3). The expe
riments also show that the relationship between the stirrup ratio and
axial load ratio is not linear if the axial load ratio is high, which
is different from the finding of previous research. In the design, a s
implified bilinear relationship can be adopted which agrees well with
the experimental results.