Site: Shibuya Viaduct
Tokyo, Japan
Date Visited: October 1996
Host: Masayoshi Okoshi, Deputy Manager, Tonen Corporation, Tokyo
Owner: Tokyo Metropolitan Expressway Corporation
Summary: Seismic retrofit of rectangular columns using tow sheet.


A set of rectangular columns outside the Shibuya subway station were retrofitted using 10 plies of FTS-C1-30 carbon tow sheet with the fibers in the hoop direction, except for the first layer which was in the longitudinal direction. The overall steps in the application process are shown in Figure B.110, and Figure B.111 shows the application of a layer of epoxy on top of the tow sheet.

Fig. B.110. Flow chart for the application of tow sheet based external reinforcement on columns.

Fig. B.111. Application of resin on top of a layer of tow sheet.

Figures B.112 and B.113 show columns before and after the application of a finish coat. Since these were rectangular columns, corners were rounded off to have a minimum radius of 10 mm. FR-E3P resin was used for impregnation. The pot life, defined as the time to gelation, is 110 minutes at 10C, 40 minutes at 20C and 20 minutes at 30C. This system is for use in spring or autumn only. The formulation is changed slightly for winter and summer.

Fig. B.112. Retrofitted column before the application of a finish coat.

Fig. B.113. Retrofitted column after the application of a finish coat. (Column is different from the one in figure B.112.)

Published: October 1998; WTEC Hyper-Librarian