Basic Study on Pretensioned Members with Ultra-High Strength Concrete
Yoshihiro HISHIKI, Toshimichi ICHINOMIYA, Toshio OHNO, Kazunori TAKADA, Yohei TAIRA and Hideki FUJII
Abstract:Ultra-high-strength concrete (UHSC) with compressive strength of 150 N/mm2 makes it possible to reduce the weight of prestressed concrete structures. Particularly in case that UHSC is applied to pretensioned members, high bond strength can also be expected to reduce the transfer length. Considerable autogenous shrinkage of UHSC, however, reduces effective prestress and causes cracking due to the restraint of reinforcing steel. A new type UHSC with less autogenous shrinkage was developed, and its basic characteristics were investigated. Prestressing tests parameterizing the type of prestressing steel and the amount of introduced stress were also conducted to determine transfer length and to verify the effect of reduced autogenous shrinkage. Furthermore the predictability of effective prestress considering shrinkage and creep strain was studied. Key Words:Ultra-high strength concrete, Pretensioned members, Autogenous shrinkage, Creep strain, Bond strength, Youngfs modulus, Tensile strength, Effective prestress, Transfer length, Prestress loss