International Concrete Abstracts Portal

"The American Concrete Institute sponsored an unprecedented six technical sessions on FRP Reinforcement for Concrete at the Vancouver Conference on March 28-31, 1993. Speakers and attendees were present from Europe, Japan, Canada and the United States. The papers in this Special Publication are organized in the same subject areas as the conference. The subject topic areas and symposium sections are: 1. FRP Material Properties and Testing Methods 2. FRP Reinforcement for Reinforced Concrete 3. FRP Reinforcement for Prestressed Concrete 4. Analysis And Design 5. The Japanese National Project for FRP Development 6. Applications of FRP Reinforcement The 55 technical papers in this report represent the most comprehensive compilation to date of FRP research, design, and application information. A comparison of the papers provides an insight to the approach to the use and development of FRP reinforcement within the research communities of Europe, Japan and North America. The two symposium volumes are also significant because substantial portions of the extensive Japanese national research project have been translated into English. The Japanese papers provide an insight to both the magnitude of the technical work being conducted in Japan and the organization of the Japanese research program." Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP138

An experimental investigation was conducted to study the shear performance of concrete beams with bar-shaped FRP reinforcement. The 35 half-scale beams were subjected to monotonically increased shear force up to ultimate capacity. The principal variables were type and reinforcement ratio of stirrup and concrete strength. The beams with FRP stirrups failed due to either breaking of the curved stirrup sections or crushing of a diagonal strut. The former failure mode was excessively brittle and more undesirable than the latter. The ultimate shear capacity increased with increasing the content of FRP stirrup, and was not so remarkably affected by the type of stirrup, although the FRP stirrups without yielding did not so effectively carry the shear force as conventional steel stirrups. Under the same stirrups, the shear capacity of the beams flexurally reinforced with FRP bars was smaller than that of the beams with steel bars. Further, it was observed that the ultimate shear capacity of beams with FRP stirrups can be fairly well estimated by substituting the tensile strength of curved sections of stirrup for the yield strength in Arakawa's formula.

Recently, a non-metallic reinforcement is developed using new synthetic fiber, such as carbon, aramid and vinylon fiber in Japan. The fiber is made into a FRP rod. This material has advanced properties, for example, corrosion free, light weight and high strength, and are expected to apply for the practical structures. However, it is important to study engineering properties and design method in many fields theoretically and experimentally. In present paper, the bond characteristics are discussed because the expansion coefficient of non metallic fiber is different from conventional concrete. The results from the pull-out tests are, (l)the bond strength of FRP rod is ensured for the concrete structures, and (2)the deterioration of bond property is not appeared in CFRP, GFRP and VFRP however a little reduction is observed at AFRP rod.

Lateral confinement of concrete members by means of spirally wrapping fiber-reinforced-plastic (FRP) composites onto the concrete surface may increase compressive strength and ultimate strain (pseudo-ductility). It may also provide a mechanism for shear resistance, and inhibit longitudinal steel reinforcement buckling. Lateral confinement of concrete members as a strengthening/repair technology is expected to have an impact in the rehabilitation/renovation of buildings and infrastructure. Structures that have been damaged, or need to comply with new code requirements, or are subjected to more severe usage are the primary targets. In this project, an experimental and analytical study of concrete strengthened with FRP lateral confinement I conducted using compression cylinders (300 and 600 mm in length) and l/4 scale column-type specimens. The latter specimens have a circular cross section and given longitudinal/transverse steel reinforcement characteristics. Column-type specimens are subjected to cyclic flexure with and without axial compression. When an aramid FRP tape is used as the lateral reinforcement, the variables are tape area and spiral pitch. In the case of filament winding with glass fiber, the thickness of the FRP shell is varied. The limited experimental results obtained at this stage of the research program indicate that lateral confinement significantly increases compressive strength and pseudoductility under uniaxial compression.

This paper reports on the effects of improvement in flexural characteristics and deformability(ductility) when using unbonded CFRP(Carbon Fiber Reinforced Plastic) tendons in prestressed concrete (PC) beams and bending fatigue characteristics of bonded type PC beams with CFRP tendons. Based on the results of flexural loading experiments, with PC beams using unbonded CFRP tendons, failure modes shifted from CFRP tendons rupture type to concrete crushing type. while deformation at the ultimate stage was also changed greatly for the better. It was also succeeded in ascertaining that effective prestressing force, and tensile reinforcement quantity and variety are influential as factors increasing deformability at the ultimate stage. Further, as the result of bending fatigue tests of bonded type PC beams with CFRP tendons, it was confirmed that reduction in ultimate flexural loads of bonded type PC beams due to repetitive loading was not seen and bending fatigue properties were favorable.