This study proposed a seismic reinforcement of RC columns with non-seismic details, a fiber reinforcement method of aramid sheets and MLCP (high elasticity aromatic polyester fiber material) with different characteristics, and 4 full-size column specimens and conducted experiments. The results show that a non-seismic specimen (RC-Orig) rapidly lost its load-bearing capacity after reaching the maximum load, and shear failure occurred. The RC column reinforced with three types of aramid did not show an apparent increase in strength compared to the unreinforced specimen but showed a ductile behavior supporting the load while receiving a lateral displacement at least 1.57 to 1.95 times higher than the unreinforced specimen. The fracture mode of the specimen, according to the application of lateral load, also changed from shear to ductile fracture through aramid-based reinforcement. In addition, when examining the energy dissipation ability of the reinforced specimens, a ductile behavior dissipating seismic energy performed 4 times greater and more stably than the existing specimens.

In recent, fiber-reinforced composites have been widely used in many fields because of their excellent performance. In order to manufacture lightweight, high-performance, and inexpensive composites various laminated structures were designed. Six types of hybrid composites were fabricated with glass/basalt/aramid fibers by VARTM process. The effect of the laminated structure on the mechanical properties of composites was investigated through impact energy, tensile and bending strength. Compared to other conditions more higher impact energy was obtained when the aramid fibers were in the center position and more higher bending strength was obtained when the fibers are laminated in the order of increasing bending performance from top to bottom. The laminate structure did not affect tensile strength which mainly depends on the property of fibers.

최근 들어 아라미드 섬유 시트는 건설 산업에 쉽게 사용되고 있다. 아라미드 섬유 시트는 높은 특성강도 및 강성, 높은 부식 저항성능, 경량 및 자기적 투명성과 같은 많은 장점을 제공한다. 본 연구에서는 아라미드 섬유 시트의 난연성능 및 접착강도가 연구되었다. 아라미드 섬유 보강 콘크리트 기둥의 내화성능은 표준 및 외부화재 곡선에 대해 서로 다른 조합의 보드 두께와 종류로 제작된 6개의 실험체를 사용하여 연구되었다. 그 결과 아라미드 섬유 시트는 마감재료를 이용해서 한 시간의 내화성능을 가지는 것으로 나타났다.

본 논문에서는 아라미드 스트립을 이용하여 영구거푸집을 제작하고 철근 콘크리트 기둥에 적용하여 성능을 평가하였다. 보강된 철근콘크리트 기둥의 구조거동을 평가하기 위하여 총 3개의 기둥을 제작하였다. 1개의 실험체는 무보강 실험체로서 비내진 상세의 기둥이며 다른 두 실험체의 경우 내진설계가 적용되거나 아라미드 섬유보강 영구거푸집으로 보강하였다. 기둥의 전형적인 성능평가를 위하여 일정한 축하중하에서 정적반복가력 실험을 수행하였다. 실험결과 무보강 실험체와 비교하여 전단 강도, 연성 및 에너지 소산능력을 증가시켰으며 반복하중으로 인한 강도 및 강성 저감에서 우수한 성능을 보였다. 따라서, 본 연구에서 제안한 아라미드 보강 영구거푸집은 기존 RC 기둥의 내진성능을 향상시킬 수 있을 것으로 판단된다.

Recently, redevelopment and reconstruction projects have caused problems such as depletion of natural aggregates, and the use of recycled aggregate is being reevaluated as an optimal alternative. Therefore, in this study, the mechanical and deformation characteristics of Environment-Friendly Recycled Coarse Aggregate (here after, EFRCA) concrete reinforced with para-aramid fiber with high strength and high elasticity are examined. The experimental main parameters were EFRCA replacement ratio (0, 30 and 50%) and para-aramid fiber volume fraction (0, 0.75 and 1.0%). Experimental results show that the EFRCA concrete has lower compressive strength than plain concrete. However, compared with the natural aggregate, the EFRCA concrete, which exhibited low material properties, showed almost the same performance as plain concrete, such as increased flexural strength and improved ductility by incorporating para-aramid fibers. Through the experiment, it is considered that the most suitable para-aramid volume fraction is 0.75%. Based on these results, the experimental results related to the performance degradation of EFRCA concrete containing para-aramid fibers are secured and basic data for determining the reuse possibility and reinforcement method of structures are presented.

The paper presents an experimental result to characterize the behaviour of steel beams reinforcement by pultruded reinforced polymer strips. Steel beam members reinforced with different thick AFRP on bottom flange plate were tested under one point bending configuration. Test results showed that the member force of one ply reinforced specimen was increased as 11% than control specimen when the two ply overlapped specimen was increased as 14% as usual.

This study focused on the static behavior of steel beams reinforcement by AFRP sheets. The main objective of the experimental programme was the evaluation of the force transfer mechanism, the increment of the beam load carrying capacity and the bending stiffness. A bending test was conducted on a H-shaped steel beam, with aramid FRP sheets bonded to its flanges. The mid-span deflection and the strain from three points along AFRP sheets were recorded Test results exhibit that the increment of the load-carrying capacity with reference to a mid-span deflection level of 15 mm(1/125mm of the clear span) was equal to 9.4% and for the two layers case, an elastic stiffness increment is slightly higher than one layer case.

In this study, structural tests were performed for the para-aramid fiber-reinforced RC beams using Recycled Coarse Aggregates (RCA) according to the main parameters which are RCA replacement ratio (0 and 30%) and para-aramid fiber volume fraction (0, 0.75 and 1.0%). Experimental results show that by reinforcing para-aramid fibers, compared with the natural coarse aggregate, the RCA, which exhibited low structural performance, improved load carrying capacity and ductility.

This paper presents the experimental results of flexural behavior of steel beam strengthened with Aramid fiber reinforced polymer plastic (FRP) strips subjected to static bending loading. Two H-beams were fabricated strengthened with aramid strips and one control specimen were also fabricated. Among of strengthened specimens, one specimen was strengthened with partial length of AFRP. From the test, it was observed that maximum increase of 16% was also achieved in bending-load capacity.

The purpose of this study is determining the effects of flexural behavior of aramid fibers in ultra high performance concrete. The 10 kinds of aramid fibers with different length, diameter and twisting were used. The flexural behavior was determined by bending tests on specimens, which was prepared by mixing 1 % of volume fractions of aramid fibers into ultra high performance concrete mortar. Consequently, the load-displacement relationship curves were obtained by using the test results for each kinds of aramid. While the specimen that contains the small diameter of aramid fiber gives the strong flexural strength due to large contact area between the fiber and concrete matrix, that specimen by small diameter of aramid fiber does not guarantee the ductile behavior of specimen like the steel fiber. But the length and twisting of aramid fiber gives the ductile behavior of ultra high performance concrete flexural specimen.

The purpose of this study is to evaluate the effect of improvement on the impact resistance and strength properties of cement composites by surface modification of aramid fiber. For aramid fiber reinforced cement composites, therefore, dispersion capability and the bonding efficiency between the fibers and the cement composite material need to be improved. It is possible by modifying surface properties to hydrophobic, it is considered that oiling agent ratio of 1.2 % and improvement of performance is in need to be investigated. In this study, short aramid fibers were mixed by different fiber length and oiling agent ratio. And improvement of strength properties and impact resistance performance of hybrid cement composites were evaluated under the influence of steel fiber. As a result, strength properties of aramid fiber reinforced cement composites are different by mixing ratio of fiber, oiling agent ratio and length of fiber. In case of cement composites which have same volume fraction and fiber length, tensile strength and flexural strength were improved with increase of the emulsions throughput of the fiber surface. The results of evaluation on the static strength properties had effects on impact resistance performance by high-velocity impact. And it was observed that the scabbing of rear was suppressed with increase of the oiling agent ratio.

강 구조물의 보강공법으로는 강판 보강공법이 대표적인 방법으로 통용되고 있으나, 일부 구조물에서는 고정 설비 및 기타 간섭물로 인하여 보강 시공이 번거롭고, 보강부재 접합시 원부재의 단면 손실이 수반되는 단점이 있다. 최근, 강재의 원가 상승으로 강판 보강공사의 시공비가 증가되고 있는 실정이다. 반면, 복합소재를 이용한 보강공사의 경우는 재료의 자중이 가벼워서 보강재 취급이 수월하고 내화학성능이 우수하기 때문에 유지비용이 절감되기 때문에 콘크리트 구조물에서는 널리 사용되고 있다. 본 논문에서는 복합소재를 이용한 강 구조물의 보강의 기술적 가능성을 검증하기 위해 강재와 복합소재와의 부착성능 및 보 부재를 통해 휨 보강 성능을 평가하였다. 그 결과, 항복 이전까지는 강재와 아라미드섬유 쉬트가 일체 거동에 따른 보강효과를 예상할 수가 있었다. 또한, 보강 겹수가 증가함에 따라 무보강 실험체 대비 내력이 증가했지만, 예상 보강효과(1겹에서 12.5%, 2겹에서 25%)에 비해 절반 정도의 수준의 개선효과를 보였다. 그 이유는 모든 보강 실험체가 계면파괴로 파단되었고, 이후 아라미드섬유 쉬트가 실험체 내력 개선에 영향을 미치지 못했기 때문이다. 따라서, 최근 복합소재의 재료적 개선 및 접착제의 부착성능 향상으로 인하여 강 구조물의 보강공사에 적용할 수 있는 가능성을 찾을 수 있었으나, 보강성능을 향상시키기 위한 부착성능 향상을 위한 방법에 대한 연구가 필요하다고 판단된다.

본 연구에서는 아라미드섬유쉬트로 휨 보강된 RC 보의 파괴양상을 분석하고, 부착파괴를 방지하기 위한 실험연구를 수행하였다. 아라미드섬유쉬트의 부착파괴 방지상세에 대한 효과를 검증하기 위하여 총 5개의 실험체를 제작․실험하였다. 분석결과에 의하면 기존에 사용되어온 단순부착식이나 단부 U보강상세를 적용한 실험체는 아라미드섬유쉬트의 재료변형률보다 낮은 변형률에서 부착파괴되는 것으로 나타났다. 반면 본 연구에서 제안한 중앙부 U보강상세와 에폭시 전단키를 적용한 실험체는 아라미드섬유쉬트의 부착파괴를 억제함으로써 충분한 보강성능을 발휘하는 것으로 나타났다