This paper presents results of inelastic pushover analyses of eight and twelve-story R/C
buildings designed and detailed according to current seismic codes for the construction in
medium seismicity areas. Two inelastic finite element packages were used in the analyses,
namely Zeus-NL and DRAIN-2D. The former employs a detailed fiber modeling, while
DRAIN-2D adopts the lumped plasticity modeling approach with member hysteretic rules
simulating numerous experimental results of various structural members. The objective is to
evaluate the redundancy and reliability of typical R/C buildings complying with current
seismic provisions. The investigation employs different reliability factors and redundancy
indices from the IBC-2003 code and from prior investigations. Differences between the
seismic response from the two modeling approaches adopted in this study are highlighted.
DRAIN-2D predictions of the ultimate strength of the eight-story building was found to be
10% lower than that of ZEUS-NL. DRAIN-2D results also indicated a three-story sway
mechanism that was not detected by the refined fiber modeling of the eight-story building.
Finally, a rational reformulation of reliability/redundancy factor is suggested. The study
concluded that buildings adequately design and detailed to current seismic codes for medium
seismicity regions have acceptable levels of reliability and redundancy.