Repair loss assessment of seismic-resistant rocking bridges

Conventionally designed (i.e. fixed-base) bridges sustain considerable damage after severe earthquakes. This seismic damage serves as an important measure of the bridge's post-earthquake functionality and often determines whether or not the bridge remains in operational condition after the seismic event. On the contrary, designing bridges to uplift and pivot (i.e. exhibiting rocking motion) during an earthquake aims to relieve the structure from stresses and damage at the plastic-hinge regions, thus, minimizes the seismic (repair) losses. In this context, rocking motion is gaining momentum as an alternative seismic isolation technique, and it has been proposed as a damage avoidance design for bridges. However, such seismic-resistant structures are still barely considered in engineering practice, due to either lack of thorough understanding of their dynamic (seismic) behavior and/or the impression that they are not cost effective. This paper redirects our attention to the benefits of rocking isolation, and conducts a thorough seismic loss assessment by comparing two different rocking bridge configurations in terms of the accumulated repair losses in the aftermath of severe seismic hazard scenarios. The results show that a rocking bridge offers a considerable post-earthquake financial benefit when carefully designed. In particular, even a slight modification of the slenderness of the structure leads to a substantial mitigation of the accumulated seismic losses. The above findings reveal the cost effectiveness of such innovative seismic-resistant structural systems, which can serve as an efficient seismic design paradigm for future bridge engineering applications.