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

PC members reinforced with FRP as tendons show brittle failure regardless of the failure mode. The authors' objective was to improve the ductility of PC members reinforced with FRP as tendons. First, the compressive properties of concrete confined with FRP as transverse reinforcement was investigated. Major improvement can be made in the stress-strain relationship of concrete laterally reinforced with FRP, and the concrete members can be given ductility characteristics similar to those of steel-reinforced members by confining the concrete with FRP. Secondly, several PC members reinforced with FRP as tendons and transverse reinforcement were tested and investigated. It was found that marked improvements could be made in the ductility of PC members with FRP tendons by confining the part of concrete subjected to flexural compression with FRP and forcing the members to undergo flexural compression compression failure. 235-493

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.

The authors had the opportunity to apply partially prestressed concrete (PPC) members reinforced and prestressed with braided aramid fiber bars to an actual structure. The PPC members were used as beams for an upper foundation of a seismic base-isolated story. The PPC beams were precast, pretensioned, prestressed concrete members reinforced with braided aramid fiber bars manufactured by braiding aramid fibers and epoxy resin impregnation. Braided aramid fibers were used as main reinforcement, prestressing tendons, and transverse reinforcement of the PPC beams. Design, fabrication, and construction of the beams are reported. Full-scale flexural tests were also conducted to insure the safety margins of the beams. Two specimens were prepared using aramid fiber bars and carbon fiber bars, with cross sections similar to the actual beams. The flexural capacity of the beam at rupture of tendons shows good agreement with the calculated capacity, which uses the average tensile strength of the bars. Full-scale fire-resistance tests were also conducted on two specimens with the same cross sections as the specimens for the flexural tests, although the design did not require fire resistance of the beams because of their use in the foundation. From the test results, the beams were considered to resist fire for about 2 hr.

An experimental study of rehabilitation methods was investigated using artificially damaged concrete beams. The rehabilitation consisted of strengthening the damaged concrete beams by external post-tensioning, and some beams were not only externally prestressed but were also specially injected with epoxy resin to repair several sizes of cracks. Static as well as fatigue tests for three-point bending were conducted to investigate the effect of these rehabilitation methods. Fatigue tests of PRC strengthened by external cable were conducted at 2 million cycles, with a stress level of 33 percent of the ultimate static beam strength and cable tension force of 34 percent of tensile strength. From these test results, the static behavior of deformation and ultimate strength of the rehabilitated beams were confirmed as reasonably upgraded and strengthened by the proposed method. The results indicate that the deflection and ultimate strength of beams for the yield stage can be estimated by theoretical calculation. For the plastic hinge formation stage, deflection and ultimate strength were also evaluated by theoretical calculation. The change in beam rigidity was found to differ insignificantly before and after fatigue tests. In the same manner, ultimate bending strength of beams before and after fatigue tests was nearly the same. As a result of measuring the ratio of loss in the tension force of aramid rope, values of approximately 10 percent were obtained for all three stress states.