Tensile performance of the recently developed “FRP Hybrid Bar” at Korea Institute of Civil Engineering and Building Technology (KICT) is experimentally evaluated by the authors. FRP Hybrid Bar is introduced to overcome the low elastic modulus of the existing GFRP bars to be used as a structural member in reinforced concrete structures. The concept of material hybridization is adapted to increase elastic modulus of GFRP bars by using steel. This hybridized GFRP bar can be used in concrete structures as a flexural member with a sufficient level of elastic modulus. In order to verify the effect of material hybridization on tensile properties, tensile tests are conducted. The results for both FRP Hybrid Bar and the existing GFRP bars are compared. The results indicate that the elastic modulus of FRP Hybrid Bar can be enhanced by up to approximately 250 percent by the material hybridization with a reasonable tensile strength. To ensure the long-term durability of FRP Hybrid Bar to corrosion resistance, the individual and combined effects of environmental conditions on the bar itself as well as on the interface between rebar and concrete are currently under investigation.

During the last two decades, fiber reinforced polymer (FRP) reinforcing bars for concrete structure has been extensively investigated and a number of FRP bars are commercially available. However, major shortcomings of the existing FRP bars are its high initial cost and low elastic modulus compared to conventional steel bars. Because of these reasons, KICT in Korea have developed the FRP Hybrid Bar which have the concept of material hybridization for concrete structures, especially for marine and waterfront concrete structures. In this study, for the discussing the applicability of FRP Hybrid Bar to real concrete structures, life cycle cost analysis were performed on small bridge and discussed considering various kinds of maintenance cases.

In the paper, newly invented FRP Hybrid Bar and normal steel are embedded in RC beam member, and ICM(Impressed Current Method) is adopted for corrosion acceleration. Corrosion amount level of 4.9∼7.8% are measured in normal RC member and the related reduction of flexural capacity is measured to –25.4∼-50.8%. But, durability evaluation through long-term submerged condition is required for actual utilization.

In the paper, accelerated corrosion test for RC (Reinforced Concrete) samples with normal steel and FRP Hybrid Bar are performed and their flexural capacity is evaluated. Furthermore UV(Ultrasonic Velocity) measurement is attempted for analysis of variation of UV due to corrosion conditions. For commercial production of FRP Hybrid Bar, bond strength evaluation through long-term submerged corrosion test is required.

This paper deals with the recent development of GFRP bars by material hybridization (i.e., “hybrid GFRP bars”). This development attempts to improve the low elastic modulus of GFRP bars to be used for reinforced concrete (RC) structures, especially they were built in a corrosive environment (e.g., waterfront structures). The purpose of material hybridization in this study is to increase the elastic modulus of GFRP bar. Steel wires were inserted to GFRP and dispersed over the cross-section. E-glass fibers and unsaturated polyester resins were pultruded. Several types of the hybrid GFRP bars were tested to evaluate the tensile strength. Mechanical behaviour of hybrid GFRP bars was examined as a function two factors: 1) a ratio of steel to GFRP; 2) a diameter of steel wire. The experimental results showed that the elastic modulus of the hybrid GFRP bar was improved by up to 171% by material hybridization. To ensure the long-term durability of the hybrid GFRP bars in waterfront structure applications, the individual and combined effects of environmental conditions on the hybrid GFRP bar itself as well as on the interface between bar and concrete should be also accessed.

The objective of this study is to develop a FRP Hybrid Bar for concrete structures, especially for marine and waterfront concrete structures. The purposes of hybridization are to increase the elastic modulus of GFRP bar with acceptable tensile strength. In this paper, using E-glass fibers and unsaturated polyester resins and steel wires, the FRP Hybrid Bar samples were pultruded and tested for tensile properties.

The purpose of this study was to analyze flexural behavior of concrete beams with steel bar and FRP reinforcement. An investigation was performed on the influence of the flexural stiffness, cracking, deflection behavior. Specimen with FRP reinforcement showed a higher strength than specimen with only steel bar. Concrete strength had an effect on improvement in flexural strength and ductile deformation.

This paper presents tensile behavior of hybrid reinforcing polymer bars. The objective of this study is to evaluate the behavior change of hybrid FRP bar according to the volume fraction and position of fibers. Considered FRP bar had 13 mm in diameter and fibers of it were glass and steel fiber. The results obtained in the FEM analysis are discussed in this paper.

FRP has higher design tensile strength than steel bar and outstanding characteristics such as light-weight, non-corrosion, and lower conductivity. And, current researchers evaluated flexural performances of flexural members using FRP and suggested the development length and splice length by using bonding failure test. This Researchers has the main purpose to examine the quality of bonding failure in the lap spliced FRP and deformed bar. Variables in this test with total 208 specimens planned are re-bar location, embedment length, covering depth, re-bar diameter. And, this study describes the result of our review on the bonding strength of the lap-spliced FRP and the deformed bar located at the bottom.

본 연구는 저자가 수행하고 있는 FRP로 보강된 콘크리트 보의 거동연구에 관한 일련의 연구 중 일부로서 본 연구에서는 인장보강근이 겹이음된 콘크리트보의 휨거동에 대한 실험적 연구결과를 제시하였다. 실험변수로는 보강근의 직경과 보강근의 겹이음길이를 적용되었으며, 총 14개의 겹이음된 실험체와 4개의 겹이음되지 않은 기준실험체에 대한 휨실험을 실시하여 각 실험변수인 보강근의 직경(10, 13, 16, 19mm)과 겹이음길이(0.72부터 1.58ld)에 대한 실험결과를 정리하였다. 각 보강근의 겹이음길이는 ACI 440에서 제시하고 있는 FRP 보강근에 대한 기준을 적용하였으며, 실험결과에서 사용된 FRP 보강근의 경우, 기준에서 제시하고 있는 부착길이에 대한 1.3과 1.6의 계수가 충분한 것으로 나타났다.

FRP bar는 높은 인장강도와 경량의 재료로 철근부식문제를 해결할 수 있는 대안으로 대두되고 있다. 그러나 FRP와 콘크리트 모두 취성적인 재료로 철근콘크리트보다 낮은 연성을 갖게 되며, 갑작스러운 파괴를 유발할 수 있다. 따라서 본 연구에서는 FRP 보강근을 사용한 휨부재의 압축측을 나선형 보강근으로 구속하여 거동을 개선하고자 하였으며, 구조실험을 통하여 파괴모드의 개선 및 연성증가를 확인할 수 있었다.

휨철근 대체재로 FRP Bar를 사용한 콘크리트 보에 대하여 휨보강근비의 변화에 따른 콘크리트의 전단강도를 일련의 콘크리트 보 실험을 통하여 조사하였다. 실험 결과, 콘크리트의 전단강도는 RC보의 경우보다는 낮은 값으로 나타났지만, 휨보강근비가 증가함에 따라 전단강도도 증가하는 것으로 분석되었다. 문헌에 제안된 식과 실험결과의 회귀분석을 이용하여 FRP Bar의 종류 및 휨보강근비를 고려한 전단강도보정계수를 제안하였다.