The purpose of this study was to improve the buckling strength of steel plate shear wall system. The variable of this study was arrangement and aspect ratio of steel plate. The arrangement of continuity and both sides were compared. And the aspect ratio 1.3 and 0.8 were compared. As a result, there was no significant difference between the arrangement of continuity and both sides, and it was observed that there was no significant difference of behavior when the aspect ratio was decreased.

In this study, the fiber blending ratio and strain rate effect on the tensile behavior of hybrid fiber reinforced cement composite was evaluated. Hooked steel fiber and polyvinyl alcohol fiber were used for reinforcing fiber. The fiber blending ratio of HSF+PVA were 1.5+0.5, 1.0+1.0 and 0.5+1.5vol.%. As a results, the tensile strength, strain capacity and fracture toughness of the hooked steel fiber reinforced cement composites were improved by the increase of the bond strength of the fiber and the matrix according to increase of strain rate. However, the tensile stress sharply decreased after the peak stress because of the decrease in the number of straightened pull-out fibers by micro cracks in the matrix around hooked steel fiber. On the other hand, PVA fiber showed cut-off fracture at strain rate 10-6/s with multiple cracks. However, at the strain rate 101/s, the multiple cracks and strain capacity were decreased because of the pull-out fracture of PVA fiber. The HSF1.5PVA0.5 shown the highest tensile strength because the PVA fiber suppressed the micro cracks in the matrix around the hooked steel fiber and improved the pull-out resistance of hooked steel fiber. Thus, DIF of strain capacity and fracture toughness of HSF1.5PVA were greatly improved. In addition, the synergistic response of fracture toughness was positive because the tensile stress was slowly decreased after the peak stress by improvement of the pull-out resistance of hooked steel fiber at strain rate 101/s

This paper provides the flexural test results of steel fiber reinforced concrete (SFRC) prisms with different aspect ratios of steel fibers (60 and 67). All mixtures have specific compressive strength of 40 MPa and steel fiber volume fraction of 0.75%. According to ASTM C 1609 and EN-14651, SFRC prisms with 150×150×550 mm were made and tested under bending loading. Test results indicated that the aspect ratio of hooked-end steel fibers has insignificant effect on the first-cracking strength and flexural behavior of SFRC prisms.

This paper provides the flexural test results of steel fiber reinforced concrete (SFRC) prisms with different aspect ratios of steel fibers (60 and 67). All mixtures have specific compressive strength of 40 MPa and steel fiber volume fraction of 0.75%. According to ASTM C 1609 and EN-14651, SFRC prisms with 150×150×550 mm were made and tested under bending loading. Test results indicated that the aspect ratio of hooked-end steel fibers has insignificant effect on the first-cracking strength and flexural behavior of SFRC prisms.

형상비(M/VD, shear span-depth ratio)가 4.5인 축소모형의 원형기둥 실험체 3개를 제작하였다. 철근콘크리트 기둥 실험체의 단면 은 원형이고 중공단면으로 제작되었다. 철근콘크리트 기둥 실험체의 단면 지름은 400 mm, 중공 지름은 200 mm이다. 일정한 축력 하에서 반복 하중을 가력하는 준정적 실험을 수행하였다. 실험체의 주요변수는 횡방향철근비이다. 모든 실험체의 횡방향 나선철근 체적비는 소성힌지 구 간에서 0.302~0.604%의 값을 갖는다. 이 값은 도로교설계기준에서 요구하는 최소 심부구속철근 요구량의 45.9~91.8%에 해당하며, 이는 내진 설계가 되지 않은 기존 교각이나 내진설계개념으로 설계되는 교각을 나타낸다. 본 연구의 최종목적은 실험적 기초자료의 제공과 함께 성능단 계별 균열거동, 하중-변위 이력곡선, 에너지 소산 능력, 등가점성감쇠비, 잔류변형, 유효강성 등 내진성능의 정량적 수치와 경향을 제공하기 위 한 것이다. 본 논문에서는 실험결과를 통해 분석된 실험변수에 따른 실험결과들을 공칭강도, 비선형 모멘트-곡률 해석 결과, AASHTO LRFD 및 도로교설계기준(한계상태설계법)과 같은 기준들과 비교하였다.

This paper describes the effects of tensile strength and aspect ratio of steel fiber on flexural behavior of high-strength SFRC notched beam. Test results indicated that flexural properties of SFRC improved with increasing in aspect ratio and tensile strength of steel fiber.

In this paper a method for measuring crack of RC members by using image analysis. Targets are attached on the surface of specimen equally in longitudinal and horizontal directions. Crack widths are measured by location of the detected targets on the images. The result compares crack patterns depending on steel ratio of the RC members. In members with high steel ratio, many additional cracks occurred after the initial crack and it reached the stabilized cracking stage. In members with low steel ratio, only one additional crack occurred after the initial crack and it was confirmed that the ductility capacity was lower in the members with low steel ratio than high steel ratio.

In this study, the uniaxial tensile tests were conducted to verify the difference of ductile behavior according to steel ratio of RC member. The tests were conducted on concrete compressive strength of 30MPa and SD400-D19 rebars. The steel ratio was classified with 0.59% and 2.87%. From the evaluation results based on limit state strain, both 0.59% steel ratio and 2.87% steel ratio were confirmed to exhibit more than 5% strain presented in korean highway bridge design code. But in case of 0.59% steel ratio, the decrease of limit state strain and failure strain was remarkably confirmed.

This paper presents an experimental study on the improvement of ductile and flexural strength for high performance fiber reinforced cementitous composites (HPFRCC). The test was evaluated by compressive and flexural behavior of HPFRCC(compressive strength : 180 MPa) according to aspect ratio and volume contents of steel fiber. The flexural strength was increased by aspect ratio near 100 or increasing volume contents of steel fiber while there is no clearly result on the compressive strength.

Steel slag has been used as the alternative binder to replace Portland cement that furthermore used as in construction and/or for stabilization/solidification of heavy metals in mine soil. One of the treatments to modify the leaching behavior of the mine soil is by carbonation. The purpose of this study was to assess the potential of carbonation in various steel slags. Based on chemical and mineralogical characterization of four kinds of slag that were used in this study, it showed that all slags had high potential for reacting with CO2 that was in accordance with the high CaO and MgO content. CO2 sequestration by aqueous carbonation of several kinds of stainless steel slags with different liquid to solid ratio was investigated in this study. The effect of chemical properties and reaction time on the performance of the carbonation process was also investigated. Converter slag, blast furnace slag (BFS) and ladle furnace slag (LFS) were used. Carbonation experiment was conducted in a closed reactor under the conditions; 1bar, 400rpm and 25℃, with solid to liquid ratios of 0.4, 0.6 and 1.0. Carbonation kinetic test was relatively fast and completed within 5 hours. The CO2 consumption increased when the liquid to solid ratio increased because of the dilution effect. Our results showed that the higher CaO and MgO contents in the slag, the higher CO2 consumption was observed. Pohang converter slag and Dangjin LFS showed slightly different tendency. At L/S ratio 0.4, Pohang slag with higher CaO and MgO content had higher CO2 consumption than Dangjin LFS. As the water content increased, Dangjin LFS had higher CO2 consumption than Pohang converter slag that was caused by the texture of Dangjin LFS with smaller particle size than Pohang converter slag. However, both Pohang BFS and Dangjin BFS have poor capacity in CO2 sequestration.

Recently, demand for construction aggregates is increasing due to the growth of construction site scale. As natural aggregate sources are becoming depleted due to high demand in construction field, the utilization of recycled aggregate (RA) as coarse aggregate in concrete is becoming more important. In this study, the authors analyze the mechanical properties of normal- and high-strength concrete beams using RA and investigate the usefulness of the minimum steal ratio for RA reinforced concrete beams. The experimental results show that application of the minimum steel ratio to RA reinforced concrete beams is possible.

In this study, it was developed hybrid fiber reinforced concrete using ground granulated blast furnace slag, the industrial wastes, and recycled aggregate. As a result of experiments on improvement of performances of eco-friendly buildings utilizing recycled resources (recycled coarse aggregates and ground granulated blast furnace slag), the following conclusions are drawn. As hybrid fiber(PVA Fiber+ Steel Fiber) was mixed with the concrete in which the replacement was conducted with recycled coarse aggregates and ground granulated blast furnace slag, the structural performance were increased.

The purpose of this study is to evaluate the corrosion protection properties of Zn/Sn metal spray method according to the contents ratio of Zn and Sn by CASS test. Also, the corrosion protection life of Zn/Sn metal spray method is evaluated by the comparing between the corrosion properties of Zn metalizing method and Zn/Sn metal spray method using CASS test. As a result, it was confirmed that the optimum content ratio of Zn/Sn in metal spray method is 60:40(65:35) (Zn : Sn volume ratio) in aspect of corrosion protection properties and construction properties. Also, it was confirmed that the Zn/Sn metal spray method had more than 3 times of corrosion protection properties cmparing the Zn matalizing method.

This research is a part of a research program to verify the seismic performance of circular reinforced concrete bridge columns with respect to longitudinal steel ratio and transverse steel ratio under cyclic lateral load. In this paper, describes mainly displacement ductility of circular reinforced concrete bridge columns with respect to test variables.

To define the shear reinforcing effect of steel fiber in high strength concrete, 4 column specimens designed with a volume fraction of steel fiber such as 0.0%, 1.0%, 1.5%, 2.0%. The column specimens were tested lateral cyclic load under constant axial load. From test results, steel fiber can reduced brittle shear failure, and can increased strength and ductility capacity in RC columns.

The damping ratios of the modes as well as the natural frequencis and the mode shapes are required to characterize the modal behavior of structure. The mode shapes and the natural frequencies are determined from analytical methods or measurements accurately. But there is little analytical basis for estimating the damping ratios although they are the most important to determine the amplitude of the vibration. Especially for the cable-stayed bridges the aerodynamic damping ratios determine the amplitude of the response to wind loads. This paper is an attempt to estimate the aerodynamic damping ratios based on measured data and quasi-static theory.

Vortex shedding occurred at relatively low mean wind velocities between 13m/s and 16m/s in the 2nd Jindo grand bridge. To control the vortex shedding Multiple Tuned Mass Damper(MTMD) was installed in the mid span. The control effects of MTMD was verified by assessing the damping ratio before and after installing MTMD. This paper present the evaluation of damping ratio of a cable- stayed bridge based on measuring data through unified remote monitoring system.

댐퍼는 지진과 같은 자연재해로 인한 구조물의 피해를 최소화하기 위해 구조물에 도입되는 에너지 저감장치로써, 이에 대한 연구와 적용은 반세기에 걸쳐 진행되어 왔다. 특히 수동형 댐퍼의 대표격인 강재댐퍼는 1970년대 초반부터 현재까지 다양한 형태의 연구가 수행되어 크고 작은 건축물에 적용되어 왔다. 본 연구에서는 국내에서 널리 사용되고 있는 슬릿형 강재댐퍼의 성능평가실험결과를 수집하여, 슬릿을 형성하는 스트럿 높이에 대한 폭비(형상비)에 항복강도 특성을 평가하였다. 주 평가 대상은 설계를 위한 항복강도이며, 실험결과대 설계식에 의한 결과를 비교하였다. 본 연구에서는 국내에서 최근 널리 사용되고 있는 강재댐퍼의 항복강도에 대한 정확한 분석을 위하여 국내외 실험결과를 대상으로 한 평가를 진행하였다. 그 결과 기존 국내 제안식이 스트럿 형상비 0.2이하, 1의 휨거동 및 전단거동이 명확한 경우의 항복강도를 예측가능한 것으로 평가되었다. 그렇지만 향후 보다 많은 실험결과를 통하여 스트럿 형상비 및 슬릿 형상에 대한 보완연구가 필요한 것으로 판단되며, 일본에서와 같이 강재 댐퍼용 저항복강재의 개발이 필요한 것으로 판단된다.

본 논문은 제강슬래그를 잔골재 대체재로 콘크리트에 활용할 경우 유리석회의 다량 함유로 인한 팽창성 때문에 콘크리트용 골재로서의 사용이 제한되고 있어 제강슬래그를 급냉시켜 유리석회의 함유량를 크게 낮춘 급냉제강슬래그를 잔골재로 활용한 콘크리트의 특성에 관한 연구이다. 따라서 급냉제강슬래그의 대체율 및 잔골재율을 달리하여 제작한 콘크리트 시험체의 슬럼프로스시험, XRD 및 SEM분석에 따른 수화특성, 재령에 따른 압축강도 시험, 길이변화시험 및 급속염소이온침투시험결과를 비교 고찰하여 급냉제강슬래그의 적정 대체율 및 잔골재율을 도출하였다.