Compared with the conventional 15.2 mm prestressed concrete strand (1,860 MPa class) specified by JIS, the super-high-tension prestressed concrete strand 15.7 mm in diameter demonstrates 20% higher stress level (2,230 MPa class) and 28% higher load level, and is used to reinforce bridges and other structures, as the strongest prestressed concrete strand in the world.
In 2011, the Japan Prestressed Concrete Engineering Association established specifications for super-high-tension prestressed concrete strands and concrete structure design and construction methods incorporating this type of steel strand and issued Guidelines for PC Structure Design/Construction Using High-Strength Prestressed Concrete. With usage established by the guidelines, our expectations are high for increased popularity of super-high-tension prestressed concrete strand.
The present product prestresses *1 a concrete structure more effectively, requiring fewer strands, than the conventional strand type. It brings about various advantages as described later on.
Starting in 2004 in the Akiba Bridge (client: NTT Urban Development Corporation; construction company: Kajima Corporation), this strand has been selected steadily in a number of structures. More recently, we delivered this product to the Uratakao Bridge on the Metropolitan Inter-City Expressway (client: Central Nippon Expressway Co., Ltd.; construction company: special construction consortium between Kajima Corporation and Hazama Corporation), as the first case of selection of the strand on expressways, and to the Matoba Viaduct on the New Tomei Expressway (client: Central Nippon Expressway Co., Ltd.; construction company: Sumitomo Mitsui Construction Co., Ltd.), which is scheduled to go into service in early summer this year. More specifically, shipped to these sites were epoxy coated and filled prestressed concrete strands *2 that offer excellent corrosion resistance.
The strand has also been planned to be used for expressway bridges in the near future. Expectations are high for this product to substantially contribute to all kinds of infrastructure development in Japan and abroad.