ERIES-DoubleDamp Blind Prediction Competition 2025–2026

The Double Damp (DD) is a bi-directional rotational friction damper designed to dissipate seismic energy without sustaining structural damage. Within the ERIES-Double Damp project, two 1:3 scale precast reinforced concrete specimens, one bare frame and one equipped with DD devices, were subjected to shake-table testing at the Paris-Saclay Research Centre under bidirectional horizontal (X–Y) and vertical (Z) near-field excitations. The experimental campaign served as the basis for a blind prediction competition aimed at evaluating the accuracy of nonlinear time-history modeling approaches. Participants were permitted to submit predictions corresponding to up to three different modal damping ratios, acknowledging the high sensitivity of dynamic response to damping assumptions. Performance evaluation was based on the prediction accuracy of maximum and residual roof displacements, as well as maximum relative floor accelerations under selected ground motions. These response quantities were defined consistently with the experimental measurement protocol, and scoring was computed using a weighted, normalized error-based framework. The adopted evaluation strategy enabled objective comparison of modeling approaches while preserving the blind nature of the study. Observed methodological trends and implications for future blind prediction initiatives are discussed.