Short-fiber reinforcement is commonly added to concrete to improve various aspects of their durability and performance. Effective designs of fiber reinforced concrete depend not only on material composition, but also on the methods of processing. In particular, the distribution of fibers within a structural component can significantly affect its resistance to cracking and, therefore, its durability when exposed to severe environments. Probability-based analyses can be used to accommodate such factors in life cycle performance evaluation, in which the relevant performance measures are described by probability density functions and their evolution over time. This paper concerns the simulation of fiber reinforced concrete using lattice models, in which the individual fibers are explicitly modeled within the material domain. This approach facilitates the study of non-uniform fiber dispersions and their potential effects on structural performance.

In this study, impact performance of steel fiber-reinforced concrete was evaluated using existing impact formulae. The existing formulae were evaluated as to whether they can predict impact performance of steel fiber-reinforced concrete well.

본 논문은 강섬유 대신 철근집합체를 사용하여 초고강도 섬유보강 콘크리트 부재의 최대하중 이후 연성거동을 유도하는 것을 목적으로 한다. 강섬유와 철근집합체의 조합을 가진 직사각형 콘크리트 보에 대한 휨거동 실험을 수행하였다. 강섬유의 혼입률은 0%, 0.7%, 1%, 1.5%, 2%이고, 연성거동을 유도하기 위한 종방향 철근 집합체의 철근비는 0.0036, 0.016, 0.028 그리고 0.036이다. 이러한 실험 요소의 조합으로 15개의 초고강도 콘크리트보가 제작되었다. 강섬유 뿐만 아니라 종방향의 철근 집합체도 초고강도 콘크리트보의 연성거동을 유도하는데 효과를 가지고 있다. 강섬유 혼입률 0.7%와 철근비 0.028인 철근집합체를 사용할 경우 가장 경제적인 조합임을 볼 수 있다. 하중과 처짐관계, 콘크리트 응력의 변화 및 균열양상 등이 좁은 간격을 가진 작은 직경의 종방향 철근 집합체의 유용성을 나타내고 있다.

Shock wave caused by the high-velocity impact causing the tensile strain and stress on the rear side. When the tensile strain and stress exceeds the tensile strength of the concrete, crack and fracture were occurred. The strain on the rear side was reduced due to Improvement of the tensile strength by fiber reinforcement and increasing the specimen thickness.

In this study, we evaluate the chloride ion permeability of steel fiber rein-forced concrete. NT Build 492 experiment was used for the evalation. During the cast of SFRC, compaction works were done in same level. As a result, the chlorine ion permeability of the steel fiber rein-forced concrete is affected by Water-cement ratio. Effect of pores in the SFRC on permeability is dominant. In conclusion, it is important to get better quality of during cast in accordance with the addition of steel fiber ratio.

Concrete subjected to dynamic loading shows local failure and it can be suppressed by improvement of flexural toughness with reinforced of fiber. Since bonding properties of fiber with matrix, specific surface area and numbers of fiber are different by fiber reinforcement type, mechanical properties of fiber reinforced concrete and improvement of impact resistance performance need to be considered. In this study, improvement mechanical properties by dynamic lodaing have been evaluated according to SF, PA fiber.

This study presents an experimental study on compressive and flexural strengths of concrete reinforced by 3D Fiber Reinforced Polymer(FRP). This study is intended to investigate the potential of 3D FRP concrete composites against impact or explosive loadings. For the comparative study, non-reinforced specimen and specimens reinforced by 3D FRP are constructed and tested. 20mm×10mm 3D fiber and 25mm×20mm 3D fiber was set to be variable.

Because significant difference between normal concrete and fiber reinforced ultra-high strength concrete under tension and compression, bond behavior also have significant difference. Based on the finite element analysis of bond test specimens, crack initiation and propagation process were investigated. Analysis results have been validated with test results and crack initiation stress was investigated.

In this study, four reinforced concrete beam-column joints, replacing recycled materials with hybrid fiber were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the seismic performance of such test specimens, such as the load-displacement, the failure mode, and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size.

Recently, studies of eco-friendly construction materials have been increased. For this reason, this paper presents the material properties of steel fiber reinforced slag concrete. Direct shear, flexural, and CMOD tests were conducted to determine the shear and flexural contribution of steel fiber.

The energy absorption capacity of ultra high performance fiber reinforced concretes (UHPFRCs) was investigated at high strain rates (45 – 92 s-1) using a strain energy frame impact machine. The UHPFRCs investigated in this study showed much higher energy absorption capacity, fracture energy, ranging 42 and 71 kJ/m2 at high strain rates than that (31 and 43 kJ/m2) at static rate. The energy absorption capacity of UHPFRC at high strain rates was strongly dependent on fiber type and fiber volume content.

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

본 연구에서는 표준실험체 (BSS), 순환굵은골재와 고로슬래그 미분말의 치환과 하이브리드섬유를 보강한 실험체 (BSPRR1, BSPRR2시리즈), 순환굵은골재와 고로슬래그 미분말의 치환과 PVA섬유를 보강한 실험체 (BSPG시리즈)로 총 13개의 실험체를 실물크기의 1/2로 축소 제작하여 실험을 수행하였다. 실험을 통하여 얻어진 결과를 비교⋅분석하여 하중-변위, 파괴형태, 최대내력 등을 규명함으로써 구조성능의 개선정도를 평가하였다. 실험결과 순환굵은골재와 고로슬래그 미분말을 치환한 콘크리트에 하이브리드섬유를 보강한 실험체 (BSPRR1, BSPRR2시리즈)의 경우 표준실험체 (BSS)에 비하여 압축강도는 최대 13%, 최대내력은 4~21%, 연성능력은 각각 4~28% 증가하는 결과를 나타내었다. 그리고 또한, 충분한 연성적인 거동과 안정적인 휨인장 파괴를 나타내었다.

In this study, four reinforced concrete beams, replacing recycled coarse aggregate with PVA fiber(BSPG-R series), were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the structural performance of such test specimens, such as the load-displacement, the failure mode and the maximum load carrying capacity. all the specimens were modeled in 1/2 scale-down size.

In this study, experimental research was carried out to improve and evaluate the seismic performance of reinforced exterior concrete beam-column joint strengthened with different anchorage length of embedded CFRP Rods in existing reinforced concrete building. Test result shows that retrofitting specimen(RBCJ-SR2T1, SR2T2) designed by the improvement of seismic performance of reinforced concrete beam-column joints, maximum load-carrying capacities were increased 2.24 ~ 2.24 times in comparison with the standard specimen(RBCJC). Also, retrofitting specimens showed stable hysteretic behavior compared to the standard specimen(RBCJC).

This research investigated the effects of adding micro fibers on the direct tensile behavior of ultra-high-performance hybrid-fiber-reinforced concrete (UHPHFRC) at high strain rates. Macro fiber was long smooth fiber (LS, Df=0.3mm, Lf=30mm) and micro fiber was short smooth fiber (SS, Df=0.2mm, Lf=13mm). The volume content of macro fibers was 1.0% and the volume content of micro fibers varied between 0.0 and 1.0%. The addition of micro fibers clearly increased the tensile strength of UHPHFRCs even at high strain rates.

Tensile stress and strain of rear by shock wave become the cause of rear side scabbing of concrete subjected to high-velocity impact. Improvement of flexural and tensile performance by fiber reinforcement has great effect on the suppression of the rear scabbing.

In this study, local fracture of concrete was evaluated through high-velocity impact test. As results, increase of bending tension performance by fiber reinforcement did not affect penetration depth Control, but it decreased rear side fracture thickness and diameter. Therefore, it was observed that fiber reinforcement decreases scabbing limit thickness.

Hokenberry and Lopez (2012) and Aoude et al. (2012) have shown that the steel fiber can be a substitute of the stirrup for shear strengthening. In this study, Vector 2 program which takes into account modified compression field theory tensile softening behaviors of SFRC were used for prediction of the shear capacities of SFRC beams.