Damage assessment of self-centering rocking piers using an input energy-based damage prediction model coupled with self-centering index

The immediate functionality of bridges following severe earthquakes is vital for uninterrupted rescue operations. Regarding the significance of resiliency in bridges, post-tensioned (PT) rocking piers with low residual displacements and minimal damages have developed over the past few decades. The rocking mechanism at two ends of the pier avoids bending moments and excessive flexural damage. The self-centering (SC) capacity in this system is provided through post-tensioning forces. Concerning optimum seismic design and retrofit purposes, it is essential to predict the actual degree of seismic damage and SC capacity of PT rocking systems after seismic hazards. In this case, a self-centering index (SI) is proposed to evaluate the SC capacity when piers are subjected to cyclic and seismic loadings. This SI, when used in co-operation with a viable damage prediction model, predicts whether or not the piers remain reparable under cyclic or seismic loading scenarios. After comparing a number of energy-based damage indices, all of which consider the cumulative hysteresis energy, with the input energy-based damage index (IEB-DI), the latter was calibrated against observed damages under cyclic loading tests. This DI was chosen as the most suitable damage prediction model and was considered to be simply applicable after time history analysis. In this study, the seismic performance of a seismic-resistant dual system, consisting of three RC bents along with an SC bent, was evaluated using the aforementioned damage limit states and the introduced SI. The damage predictions of the monolithic bridge, as the reference model, were compared with the estimated damage to the dual bridge. The results show that the joint application of the IEB-DI and the proposed SI in predicting the performance level of SC rocking piers results in a comprehensive damage prediction model.