The objective of this study is to investigate the seismic vulnerability of elevated steel storage tanks supported by reinforced concrete (RC) columns using a nonlinear time-history analysis and a probabilistic seismic assessment. As a case study, an elevated tank, which collapsed during the Kocaeli Earthquake in 1999 at Habas plant in Turkey due to insufficient strength of support columns, has been presented. Nonlinear time history analyses are conducted based on a simplified lumped mass model for the liquid steel storage tank and a three-dimensional (3D) nonlinear model for the support structure in order to evaluate the earthquake performance of the tank components during the different intense shakings of the earthquakes. Probabilistic seismic demand models incorporating uncertainty parameters for the tank are then established and compared to develop corresponding fragility curves.