Quantifying seismic resilience of single-column rocking bridges - a comparative study

Abstract

This study focuses on structural systems which are particularly attractive for bridge design. Specifically, it investigates the seismic performance of single-column bridges, which are either conventionally designed, with the column monolithically connected with the ground (i.e. fixed-base), or designed with the column-footing system able to uplift and exhibit planar rocking motion during an earthquake. Conventionally designed bridges sustain considerable damage at the column ends after severe earthquakes. Seismic damage often determines whether the bridge remains functional after a seismic event. On the contrary, rocking design implies that a structure under seismic loading performs rigid body rotation around pre-defined pivot points. Thus, in principle, it relieves the structure from excessive deformations and damage. However, rocking isolation is not often applied in bridge engineering practice, mainly due to the lack of thorough understanding of its dynamic (seismic) performance and its potential post-earthquake financial benefits. This paper redirects our attention to the main benefits of rocking design over the conventional (fixed-base) design and conducts a comparative study between the two design methodologies in terms of their seismic losses and resilience in the aftermath of severe seismic hazard scenarios. The analysis reveals the mitigated seismic losses and the remarkable resilience that rocking design offers compared to the conventional (fixed-base) design after all the examined seismic hazard scenarios. The above findings reinforce the potential of the rocking design as an alternative seismic design paradigm for future bridge engineering applications and serve as the basis for a more rational and holistic seismic assessment of single-column rocking bridges.