Finite element analyses of confined columns are presented.
Based on a confinement dependent uniaxial concrete model,
the importance of the yield strengths of the stirrups and the
longitudinal reinforcement bars, the spacing of the stirrups,
and the configuration of the cross-section, in combination
with different load eccentricities are evaluated. It was found
that the spacing of the stirrups and the reinforcement
configuration are of the greatest importance for the post-peak
behavior. To achieve ductile structural behavior of highstrength
concrete columns, a higher value of the volumetric
stirrup ratio is required. However, it was found that, even for
concretes currently accepted by the code, a higher ratio than
that corresponding to the required maximum spacing of 15f is
needed to obtain the same ductility as a concrete of grade
K40.
