In Japan, due to the South Hyogo Prefecture Earthquake attacked urban area in 1995, various railway concrete structures sustained extensive damage never experienced before. Therefore, the seismic design standard has been greatly improved, and the seismic retrofitting of existing structures was started on a full scale. As most common seismic retrofitting techniques for reinforced concrete rigid-framed viaduct, there are steel plates jacketing and concrete jacketing with reinforcing bars. However, as the space under railway viaducts in urban area is used for railway equipments, commercial facilities, and other buildings, the construction of seismic retrofitting have to be done in a constrained environment. So it is difficult to retrofit by conventional seismic retrofitting techniques with large construction equipment such as cranes. Then, authors developed original various seismic retrofitting techniques that it is possible to keep function of railway equipments and business of commercial facilities, and apply according to a local situation. In full paper, following new seismic retrofitting techniques are described.
1. Retrofitting work depositing layer upon layer of light weight and thin plates about 0.8mm thick by resin-based adhesive around column by hand work only.(Fig.1)
2. Retrofitting work carried out from only surface of a column, using a steel plate and reinforcing bars.(Fig.2)
3. Retrofitting work arranging only external lateral reinforcing bars around column by hand work.(Fig.3)