|主題||Flexural Behavior of Composite Beam Using a U-Shaped Short-Fiber-Reinforced Concrete Form Prestressed with FRP Tendons|
|筆頭著者||Tetsushi Kanda（Kajima Technology Research Institute）|
|連名者1||Shigeo Watanabe（Kajima Technology Research Institute）|
|連名者2||Mikio Kobayashi（Kajima Technology Research Institute）|
Fiber Reinforced Plastic (FRP) tendons have recently been developed for application to structures. FRP tendons are characterized by their high durability, high strength and light weight. However, when these materials are used in partially prestressed concrete beams, their low stiffness produces problems at higher than concrete cracking loads. Moreover, Reinforced Concrete (RC) structure construction utilizing precast concrete forms has been popularized in Japan. To reduce transport cost of elements, these forms must be light and strong. Therefore, they must have small cross sections and they must utilize light-weight high-strength concrete.
Flexural loading tests were carried out to investigate the structural performance of a U-shaped concrete beam form using discontinuous-short-Carbon-Fiber-Reinforced Concrete (CFRC) pretensioned-prestressed with Aramid-FRP (AFRP) tendons and including steel reinfoldng bars. The flexural behavior of composite beams comprising this form filled with insitu concrete was also scrutinized. These tests were performed to verify: 1) the applicability of unsupported prestressed CFRC forms to the construction process, and 2) the structural superiority of composite beams using these forms.
If steel tendons were used for these forms, cover thickness would have to be increased due to their high corrosibility. This would reduce the prestressing effect and increase form weight. Furthermore, if plain concrete were used, much higher prestressing force would be necessary to realize the required performance. Use of the AFRP tendons and CFRC enable these problems to be resolved. This study assisted in development of a new type of beam element which can be applied to actual structures.
This study investigated the flexural behavior of pretensioned-prestressed U-shaped CFRC forms and composite beams using these forms. The following conclusions can be made: 1) these forms can be applied unsupported to actual construction processes, 2) Hybrid reinforcement combining AFRP tendons and steel reinforcing bars produces a beam that is stronger than an AFRP-only reinforcement beam, 3) the effect on a composite-beam's structural behavior of prestressing in a U-shaped form is similar to that of ordinary prestressing in a full beam section, and 4) with the use of CFRC, these forms can produce composite beams with excellent.