Seismic retrofitting of existing road bridges – current state of practice

Abstract

Seismic assessment and subsequent retrofitting of existing road bridges is a growing challenge for structural engineers in earthquake-prone areas. Following the two catastrophic earthquakes which occurred in the last two years in Croatia, the awareness (both from the engineers and public) for older existing road bridges is heightened. As they were designed according to old codes, and due to their age, deterioration, and increased traffic volume over the last decades, these bridges are in need of assessment (and retrofitting when required). The first part of the paper provides a theoretical overview of bridge behavior during seismic events and the identification of critical structural elements, based on the bridge type and size. In the second part, the review on the most commonly used techniques for seismic retrofitting of these bridges is given, with practical examples were available. The techniques are divided based on the corresponding structural elements and bridge types, with a focus on reinforced and prestressed concrete bridges as the most common bridge types in Croatia and the surrounding region.