Performance-based earthquake engineering (PBEE) is based on the premise that the performance of engineered facilities can be predicted and evaluated with sufficient degree of confidence. However, prediction of system response greatly depends on the analyst’s experience and modeling skills. Therefore, the uncertainty with which the engineering community can predict response of a system or one of its components should be realistically quantified in PBEE. A blind prediction contest of a full-scale reinforced-concrete bridge column exposed to six consecutive unidirectional ground motions of different intensity was conducted to identify the uncertainty of the predictions of important response quantities. Predictions submitted by forty-one teams were statistically analyzed, which showed great scatter in predictions of basic engineering response parameters. For instance, the average coefficients of variation in predicting maximum displacement and acceleration over six ground motions were 39% and 48%, respectively. Biases in median predicted responses were also significant, varying from 5% to35% for displacement and from 25% to 118% for acceleration. Although the results of this blind prediction contest provide data regarding the modeling uncertainty of modern bridge columns, more than anything these results stress the need for a comprehensive analytical study that establishes guidelines on bridge column modeling, with the goal of reducing the uncertainties.
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