• Title, Summary, Keyword: 항복비

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An Experimental Study of Flexible-Stiff Mixed System of High Yield Ratio-High Strength Steel for the Practical Use (고항복비-고강도강의 유강혼합구조 시스템 적용에 관한 실험적 연구)

  • Oh, Sang Hoon;Kim, Jin Won;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.17 no.4
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    • pp.395-405
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    • 2005
  • This paper summarizes the test results of the flexible-stiff mixed system for the effective use of high-strength steel. Steel with a high degree of strength and performance is being increasingly required as buildings get larger and taller. High-strength steels cannot be used for many applications, though, because they have a number of defects. For instance, they have a high yield ratio, a small strain in maximum stress, and equal Young's modulus compared to mild steels. A new structural system is needed to effectively use high-strength steels with some defects. This paper proposes the flexible-stiff mixed system for the effective use of high-strength steels with high yield ratios. The possibility of using the system is discussed through the test of flexible-stiff mixed columns with high-strength steels. The main variable of the specimens is the yield displacement ratio, including both the force ratio and the stiffness ratio. The proper yield displacement ratio is proposed by adopting the flexible-stiff mixed system. The test results showed that the proposed flexible-stiff mixed system has a high capacity for energy absorption and the highest capacity for energy absorption when the yield displacement ratio of the flexible element to the stiff element ranges from 2.7 to 3.3.

An Availability Analysis on the Gap K-Joints using High Strength Circular Hollow Section Members (고강도 원형강관 갭K형 접합의 사용성 해석)

  • Ahn, Kwan-Su;Choi, Byong-Jeong;Oh, Young-Suk;Kim, Jae-Woon
    • Journal of Korean Society of Steel Construction
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    • v.22 no.2
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    • pp.109-119
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    • 2010
  • There are many restrictions in the application of high-strength HSSs, including yield strength and yield ratio for the 600-MPa steel. The AISC and Canadian codes recommend that the yield strength and yield ratio of HSS members be 360 MPa and 80%, respectively. It is important to understand the true buckling behaviors of HSSs using high-strength steel at the limit states. There are many experimental data regarding the rectangular HSSs, and the circular ones are not enough for high-strength steel. Therefore, this study was conducted to create a better understanding of the buckling behaviors of the 600- and 400-MPa steels based on the results of the finite-element analysis that was done before the experiment. To understand the structural behaviors of the aforementioned steels, the width-to-thickness ratios, the angle of the web members, the yield strength, and the gap of the web members were selected as the main parameters in this study, and ABAQUS, a general finite-element program, was used.As a result, the compression web member reached elastic buckling in the 600-MPa steel and inelastic buckling in the 400-MPa steel. A brittle fracture occurred in the case where the yield ratio was greater than 80%. At the same time, it was found that the limit strength determined via FEM analysis had a higher value compared to the code evaluation with the variation of the width-to-thickness ratio in the main code member. The change in the connection load in high-strength steels was not identified by the other factors.

Analytical Study on Characteristics of von Mises Yield Criterion under Plane Strain Condition (평면변형률상태에서의 von Mises 항복기준의 특성에 관한 이론적 연구)

  • Lee, Seung-Hyun;Kim, Byoung-Il
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.9
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    • pp.6391-6396
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    • 2015
  • In order to investigate characteristics of the von Mises yield criterion under 2 dimensional stress condition, two cases of plane strain were studied. One of which was for zero elastic strain and the other was for zero plastic strain increment. Yield functions for the plane strain condition for zero elastic strain and for the plane stress condition were represented as ellipse and the two yield functions were compared by ratios of major axis, minor axis and eccentricity and it was seen that the ratio of minor axis was the same between the two cases and the ratios of major axis and eccentricity were functions of Poisson's ratio. Region of elastic behavior obtained from considering plane strain condition of zero elastic strain increases as the Poisson's ratio increases. Yield function for plane strain obtained from considering zero plastic increment and associate flow rule was displayed as straight line and the region of elastic behavior was greater than that for the case of plane stress.

Inelastic Behavior of Reinforced Concrete Frame Structure with Shear Strength of Masonry Wall (조적벽의 전단강도를 고려한 철근콘크리트골조의 비탄성 거동)

  • Yoon, Tae-Ho;Kang, Kyung-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.9
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    • pp.4216-4222
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    • 2011
  • In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

Failure Modes of RC Beams with High Strength Reinforcement (고강도 비틀림보강철근을 사용한 철근콘크리트 보의 파괴모드)

  • Yoon, Seok-Kwang;Lee, Su-Chan;Lee, Do-Hyeong;Lee, Jung-Yoon
    • Journal of the Korea Concrete Institute
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    • v.26 no.2
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    • pp.143-150
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    • 2014
  • To avoid abrupt torsional failure due to concrete crushing before yielding of torsional reinforcement and control the diagonal crack width, design codes specify the limitations on the yield strength of torsional reinforcement of RC members. In 2012, Korean Concrete Institute design code increased the allowable maximum yield strength of torsional reinforcement from 400 MPa to 500 MPa based on the analytical and experimental research results. Although there are many studies regarding the shear behavior of RC members with high strength stirrups, limited studies of the RC members regarding the yield strength of torsional reinforcement are available. In this study, twelve RC beams having different yield strength of torsional reinforcement and compressive strength of concrete were tested. The experimental test results indicated that the torsional failure modes of RC beams were influenced by the yield strength of torsional reinforcement and the compressive strength of concrete. The test beams with normal strength torsional reinforcement showed torsional tension failure, while the test beams with high strength torsional reinforcement greater than 480 MPa showed torsional compression failure. Therefore, additional analytical and experimental works on the RC members subjected to torsion, especially the beams with high strength torsional reinforcement, are needed to find an allowable maximum yield strength of torsional reinforcement.

An Experimental Study on the Strengh and Ductility of High-Strength Flexural Members (고강도 휨재의 강도와 연성에 관한 실험적 연구)

  • Lee, Seung-Joon
    • Journal of Korean Society of Steel Construction
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    • v.13 no.1
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    • pp.19-28
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    • 2001
  • The strength and ductility of steel flexural members are investigated experimentally in this study. As for the performance evaluation of flexural members. experimental studies on the 9 test specimens were carried out. Four specimens were fabricated from SM490 and five specimens were fabricated from SM570. The experimental results of the specimens were analyzed with focus on the flexural strength and ductility. The experimental results exhibited that all the specimens provided sufficient flexural strengthes which exceeded the nominal flexural strengthes specified in the current Limit State Design Specification by average ratio of 1.22. However. the experimental results showed that the compact-section specimens fabricated from SM570 did not provide the required rotational ductility. The yield-to-tensile strength ratio(YR) of SM570 of about 0.9 might be the causes of such insufficient capacities.

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Vibration Control Effect of the Framed Building Structures according to the Stiffness Ratio of Exo-type Damping System and Damper Device Yield Ratio (Exo-type 감쇠시스템의 강성비와 감쇠장치의 항복비에 따른 라멘조 건물의 제진효과)

  • Hur, Moo-Won;Lee, Sang-Hyun;Chun, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.5
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    • pp.38-44
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    • 2015
  • In this paper, the vibration control effect of the Exo-type damping system was investigated by applying the Kagome dampers to 15-story and 20-story frame structure apartment. A new Exo-type damping system composed of the dampers and supporting column was proposed in the previous work and numerical analysis were performed to investigate the effects of optimum stiffness ratio between controlled structure and supporting column, the size of damper and yield ratio of the damper. The numerical analysis results of a structure with Exo-type damping system up to the third story showed that the stiffness ratio should be higher than 7.0 and the damper device yield ratio be at least 8.0% ($V_{damper}/V_{base\;shear$) to effectively reduce the base shear and the maximum drift of the uppermost story. When the Exo-type damping system was installed up to the fifth story, the stiffness ratio should be higher than 2.5 and damper device yield ratio needs to be at least 3.5% ($V_{damper}/V_{base\;shear$) for obtaining the target performance.

Evaluation of fatigue poperties of base and weld metal for API 5L X65 pipeline (API 5L X65 배관 모재 및 용접부 피로특성 평가)

  • Kim, Cheol-Man;Baek, Jong-Hyun;Kim, Woo-Sik
    • Proceedings of the KSME Conference
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    • pp.44-48
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    • 2001
  • The pipelines for natural gas transmission were buried in the ground of 1.5m depth. The pipelines were continuously subjected to vehicle load and internal pressure change by the quantity consumed of natural gas. In this paper, high cycle fatigue properties of natural gas transmission pipelines were studied. Fatigue specimens were obtained from the base and weld metal of circular pipe. Fatigue strength increased with increasing yield strength. Especially, the fatigue strength of base metal was higher than the yield strength of base metal and the fatigue strength of weld metal by manufactured process of TMCP.

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Estimating Unsaturated Shear Strength and Yield Load of Compacted Aggregate Sub-base Materials (다져진 보조기층 재료의 불포화 전단강도 및 항복하중 평가)

  • Jeon, Hye-Ji;Park, Seong-Wan
    • Journal of The Korean Society of Civil Engineers
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    • v.31 no.4D
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    • pp.571-576
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    • 2011
  • In general, conventional road pavements are designed under the assumption that the shear strength of geomaterials are under saturated state. In reality, however, most of the pavement geomaterials exists under the unsaturated state. To deal with this gap between saturated and unsaturated conditions, in this paper, unsaturated shear strength was estimated using the results from the triaxial compression test and soil-water characteristics curves. Then, yield loads were assessed using 2-Dimensional finite element method with the selected nonlinear elastic model and the Mohr-Coulomb yield criteria. In addition, various unsaturated condition and surface layer effects on the yield load of granular materials were identified. Therefore, the results demonstrated would provide a possibility to estimate bearing capacity of paved or unpaved roads using unsaturated soil mechanics.

多孔性 금속의 소성역학

  • 오흥국
    • Journal of the KSME
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    • v.22 no.3
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    • pp.191-195
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    • 1982
  • 소결 금속(sintered metal)은 기공(pore)의 존재로 성형에 있어서 체적변화를 유발하므로 이제까지 사용되어오던 체적변화를 유발하므로 이제까지 사용되어오던 일반 소성이론(conventional plasticity theory)은 적용할 수 없기 때문에 소결금속에 대한 소성이론을 정립해 오고 있다. 그 발달 과정을 보면 미국과 일본에서 각각 독자적인 방법으로 진행되었는데 미국에서는 Kuhn씨가 포아숀 비(.nu.)를 정의하여 실험적으로 구하고 이것을 기초로 하여 항복조건을 정립하고 응력과 변형도율과의 관계를 유도해 냄과 동시에 알루미늄 분말 소결원판 단조에 적용하여 그 실용성을 예시하였다. 한편 일본에서는 교오토오 대학의 Shima, Oyane등이 연구 정립한 것으로서 다공정 금속과 그 본금속의 항복 응력비와 정수압의 항복 응력에 대한 영향도를 정의하여 실험을 통하여 결정한 다음 항복조건을 만들고 이로부터 응력과 변형율과의 관계, 등가 변형율을 유도하였고 이를 폐금형 압축시험에 적용하였다.

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