Proposed seismic-resistant dual system for continuous-span concrete bridges using self-centering cores

Abstract

Self-centering (SC) rocking bridge piers can retain the bridge functionality after an earthquake by limiting residual drifts. Nevertheless, it is not necessary to use the SC rocking piers at every bent of a bridge system. In a bridge with monolithic pier-deck connections, even one SC bent can affect the seismic performance of the entire system, pulling other bents back toward their original location. Accordingly, a new SC system is proposed, consisting of a bridge with conventional reinforced concrete (RC) piers working along with an SC core during seismic loading. In this study, four different types of bridge piers are considered: RC piers, post-tensioned RC piers, and SC rocking piers with or without external dissipators. A primary bridge with conventional RC piers is modeled, and secondary models, consisting of the four mentioned piers and SC cores, are derived from it. The seismic behavior of bridges is examined and compared through fragility analysis. For this purpose, fragility curves of the bridge models were developed using drift ratios and residual drifts as engineering demand parameters (EDPs). The results showed that using SC rocking piers significantly reduces the residual displacements but increases the probability of exceeding a low-drift performance level. Furthermore, additional dissipators are needed to preserve structural stability. On the other hand, the SC core decreases both maximum and residual drifts, even with no dissipators at all performance levels, reducing damage and the probability of emergent usage interruption after an earthquake.