Seismic performance and resilience quantification of a rocking bridge frame

Conventionally designed bridges, i.e. when the column is monolithically connected with the ground (fixed-base), sustain considerable damage at the column ends after severe earthquakes. Seismic damage often determines whether or not the bridge remains functional after an earthquake event. Rocking isolation, on the other hand, allows structural components to uplift and pivot; thus, in principle, it relieves the structure from excessive deformations and damage. However, rocking isolation is still rarely applied in engineering practice, mainly due to the lack of thorough understanding of its dynamic (seismic) performance and its post-earthquake financial benefits. This paper redirects our attention to the main benefits of rocking design, and conducts a thorough seismic loss assessment adopting two different rocking bridge configurations in terms of their post-earthquake economic losses and resilience. In particular, this work extends the well-established performance-based earthquake engineering framework to evaluate the seismic losses of the examined rocking structures accumulated following severe seismic events and quantify their post-earthquake resilience. The analysis reveals the considerably mitigated seismic losses and the remarkable post-earthquake resilience that a rocking bridge offers when carefully designed. In particular, even a slight modification of the slenderness of the structure leads to a substantial enhancement of its seismic performance; reinforcing its potential as an alternative seismic design paradigm for bridges. The above findings illustrate the considerable financial benefits of such innovative seismic-resistant structural systems, which can serve as an efficient seismic design paradigm for future bridge engineering applications.