Advancements in retrofitting reinforced concrete structures in Japan using FRP sheets

In Japan, many reinforced concrete bridge structures collapsed in the recent severe earthquakes such as the 1995 Hyogoken-Nanbu Earthquake and the 2004 Niigataken-Tyuetsu Earthquake were designed and constructed before the introduction of the new seismic resistant design codes in 1980. Following the lessons learnt from these severe earthquakes and the continuous advancements of the state of the art and practice, further stringent performance based earthquake resistant design codes for both highway and railway bridge structures are recently enforced in Japan. For many existing structures, to meet the requirements of these new codes, proper strengthening schemes must be implemented. Among various strengthening techniques, the application of fiber reinforced polymer (FRP) has recently drawn a wide attention due to its advantages such as high strength to weight ratio, corrosion resistance, and ease of execution. This paper introduces the current issues related to the deficient reinforced concrete structural members in Japan and provides an overview of latest innovations and advancements in the technology and application of FRP sheets in structural retrofitting. The focus of this paper is mainly on the retrofitting of bridge superstructures and substructures including decks, girders, frames, and columns