• Title/Summary/Keyword: 전단응력-변형

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A Study on the Post-buckling Behavior of Slit Type FLD(Force Limiting Device) (슬릿형 응력제한장치(FLD)의 좌굴 후 거동에 관한 연구)

  • Oh, Young Suk;Kim, Cheol Hwan;Kim, Chae Yeong;Chae, Won Tak
    • Journal of Korean Society of Steel Construction
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    • v.25 no.5
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    • pp.475-486
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    • 2013
  • This research is about design of slit type FLD which secure the buckling stability of compressive brace. 4 slit type and 8 slit type specimens were experimented by pure compressive loading. Comparing the experiment results with FEA results, the good correspondence is appeared each other. Also for deriving strength-displacement formular, an unit section of slit type FLD is transferred to idealized sandwich section. This formular explains satisfactorily experiment results, in given condition. The result of this research will be used as basic data in FLD design.

Engineering Characteristics of Diatom Modified Soil Mixture (Diatom 혼합토의 공학적 특성)

  • Kim, Kyu-Sun
    • Journal of the Korean Geotechnical Society
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    • v.28 no.5
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    • pp.77-84
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    • 2012
  • The engineering characteristics of natural sediments containing diatom microfossils have been investigated for their abnormal deformation and strength behavior for a few decades. The presence of disk or hollow shape diatoms causes low compressibility, high hydraulic conductivity, and high shear strength of sediments. Some of these unusual differences show the characteristic of diatom owing to the interlocking of large interparticle porosity and angular particles. This phenomenon implies the possible use of diatom as modification materials to change the engineering performance of soil mixtures. This paper describes the engineering characteristics of diatom-kaolin mixture to investigate the engineering properties of diatom modified soils using conventional geotechnical tests and elastic and electromagnetic wave propagation tests. Experimental test results show the performance improvement by increasing diatom contents and the performance degradation by the breakage of interlocking between diatom particles under high effective stress.

Enhancing the Performance of High-Strength Concrete Corbels Using Hybrid Reinforcing Technique (하이브리드 보강기법을 활용한 고강도 콘크리트 내민받침의 성능 향상)

  • Yang, Jun-Mo;Lee, Joo-Ha;Min, Kyung-Hwan;Yoon, Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.13-16
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    • 2008
  • Corbels are short cantilevers that project from the faces of a column and are a type of stress disturbed member, resisting both the ultimate shear force applied to them by the beam, and the ultimate horizontal force caused by shrinkage, temperature changes, and creep of the supported elements. Recently, as there have been an increase in the use of high-strength concrete and the concern about corrosion problems, lots of researches about hybrid reinforcing technique, applying strategically high performance reinforcements to the concrete elements, are performed. In this study, fiber reinforced high strength concrete corbels were constructed and tested for applying hybrid reinforcing technique to the corbels using steel fibers and headed bars. The results showed that the performance in terms of load carrying capacities, stiffness, ductility, and crack width was improved, as the steel fibers were added and the percentage of steel fibers was increased. In addition, the corbel specimens used headed bars as main tension ties showed superior load carrying capacities, stiffness, and ductility to the corbel specimens anchored main tension ties by welding to the transverse bars.

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Seismic Performance of Precast Infill Walls with Strain-Hardening Cement Composite (변형경화형 시멘트 복합체를 사용한 프리캐스트 끼움벽판의 내진성능)

  • Kim, Sun-Woo;Jeon, Esther;Kim, Yun-Su;Ji, Sang-Kyu;Jang, Gwang-Soo;Yun, Hyun-Do
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.89-92
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    • 2008
  • The seismic behavior of the lightly reinforced concrete frames (LRCFs) was controlled by the nonductile behavior of the critical regions. These critical regions require retrofit to improve the seismic behavior of the lightly reinforced concrete frames. Critical column end regions must be retrofit to increase the global ductility capacity. The objective of this research is to evaluate structural strengthening performance of lightly reinforced concrete frame with Strain hardening cement composite(SHCC) experimentally. The experimental investigation consisted of a cyclic load tests on 1/3-scale models of precast infill walls. Reinforcement detail of infill wall was variables in the experiment. The experimental results, as expected, show that the multiple crack pattern, strength, ductility and energy dissipation capacity are superior for specimen with SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

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Structural Capacity of Steel Plate Walls According to Various Infill Plate Details (다양한 웨브강판 상세에 따른 골조강판벽의 구조성능)

  • Park, Hong Gun;Choi, In Rak;Jeon, Sang Woo;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.19 no.1
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    • pp.67-78
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    • 2007
  • In this study, we performed an investigation on the variations in the structural capacity of steel plate walls with various infill plate details. Five three-story plate walls with thin web plates were tested. Parameters for the test specimens were the connection details between the moment frame and infill plates, such as weld and bolt connections, the location and length of weld connection, and coupling wall. Regardless of the details of infilled steel plate, the steel plate wall specimens showed excellent initial stiffness, strength, and energy dissipation capacity. However, the wall with bolt-connected infill plates showed slightly low deformation capacity. This result showed that for workability and cost efficiency,various wall details can be used in practice without causing a significant decrease in the structural capacity of steel plate walls. A method for making projections on strength and energy dissipation capacity of steel plate wall specimens with various details was developed.

A Study of MD Constitutive Model Calibration for Coarse-grained Soils (조립재료에 대한 MD 구성모델 캘리브레이션 연구)

  • Choi, Changho;Shin, Dong-Hoon
    • Journal of the Korean Geosynthetics Society
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    • v.12 no.1
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    • pp.63-72
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    • 2013
  • The structural stability of fill dam largely depends on the engineering behavior of rock materials used as main zone for dam construction and it is necessary to understand well the stress-strain characteristics of fill materials as well as shear strength property. In addition, the numerical analysis of fill dam requires a thorough study for calibrating material properties and parameters of a coarse-grained soil constitutive model. In this paper, large triaxial test results for Buhang-dam fill materials are analyzed and constitutive model parameters are calibrated based on the test results. It is shown that MD constitutive model is capable to predict the stress-strain behavior of dense and loose coarse-grained soils used for Buhang-dam construction based on the comparison study between the experimental test result and numerical simulation.

General Theory for Free Vibration and Stability Analysis of Thin-walled Space Frames (박벽 공간뼈대구조의 자유진동 및 안정성해석을 위한 일반이론)

  • 김문영;김성보
    • Computational Structural Engineering
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    • v.11 no.1
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    • pp.191-204
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    • 1998
  • The general formulation for free vibration and stability analysis of unsymmetric thin-wared space frames is presented in case where the shear deformation effects are neglected. The kinetic and total potential energies are derived by applying the extended virtual work principle, introducing displacement parameters defined at the arbitrarily chosen axis and including warping deformation and second order terms of finite semitangential rotations. In formulating the finite element procedure, cubic Hermitian polynomials are utilized as shape functions of the two node space frame element. Mass, elastic stiffness, and geometric stiffness matrices for the unsymmetric thin-walled section are evaluated, and load-correction stiffness matrices for off-axis distributed loadings are considered. In order to illustrate the accuracy and practical usefulness of this formulation, finite element solutions for the free vibration and stability problems of thin-walled beam-columns and space frames are presented and compared with available solutions.

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An Experimental Study of the Long-term Creep characteristic of High Damping Rubber Bearings (고감쇠 고무받침의 장기 크리프 특성에 대한 실험적 연구)

  • Oh, Ju;Park, Jin-Young;Park, Kun-Nok;Kim, See-Dong;Park, Sung-Kyu
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.1
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    • pp.53-60
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    • 2009
  • Isolated structures use devices such as high damping rubber bearings (HDRB) in order to dramatically reduce the seismic forces transmitted from the substructure to the superstructure. The laminated rubber bearing is the most important structural member of a seismic isolation system. The basic characteristics of rubber bearings have been confirmed through compression tests, compressive shearing tests and creep tests. This paper presents the results and analysis of a 1000hr, ongoing creep test conducted at 7.5MPa, 8.37MPa in our laboratory. The long-term behavior of bridge bearings, such as high-damping rubber bearings, will be discovered through a compression creep test subjected to actual environmental conditions. These tests indicated that the maximum creep deformation is about $0.3{\sim}1.92%$ of total rubber thickness.

Evaluation of Engineering Properties of Clays Through Flat Dilatometer Tests (Flat Dilatometer 현장시험을 통한 점토 지반의 공학적 성질 추정)

  • Lee, Seung-Rae;Kim, Yun-Tae;Kim, Jun-Seok
    • Geotechnical Engineering
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    • v.8 no.3
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    • pp.23-36
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    • 1992
  • The flat dilatometer(DMT) has been practically used as an in-situ test equipment. It is a simple, rapid and cost-effective tool to characterize the in-situ stress-strain-strength properties of various types of ground materials. However, the results of flat DMT should be validated with considerable data with respect to the known reference values for a specific site. In this study, the applicability of existing relationships which were established for other local deposits is verified by performing the tests in several clay deposits. To compare with the DMT results, field vane tests and cone penetration tests were also carried out in the same field as reference tests, and unconsolidated undrained tests, oedometer tests, and other fundamental material properties tests were conducted on the thin-walled tube samples in the laboratory. The results of the flat DMT combined with empirical correlations are used to estimate soil types, unit weights, coefficients of lateral earth pressure at rest, overconsolidation ratios, constrained moduli and undrained shear strengths of three clay local deposits. It was found that various geotechnical properties estimated from the flat DMT generally well agree with those from the reference tests.

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Experimental Study on the Triaxial Compressive Behaviour of Unsaturated Compacted Silt under Various Suction Levels (다양한 석션 레벨에서의 불포화실트의 삼축압축거동에 관한 실험적 연구)

  • Kim, Young-Seok;Oka, Fusao
    • Journal of the Korean Geotechnical Society
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    • v.24 no.1
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    • pp.25-35
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    • 2008
  • It has been recognized that the behaviour of unsaturated soil plays an important role in geomechanics. However, up to now, only a few experimental data are available for the technical difficulties related to both volume changes and suction measurements. In this study, the volume changes of unsaturated compacted silty soil were monitored with proximeter during various triaxial compression tests, which gave a realistic estimation in the volume changes of unsaturated soil sample. From the test results, the behaviours of wetting-induced collapses are observed during the drainage/water absorption tests. Under exhausted-drained conditions during shearing, the shear strength increases with an increasing initial suction. On the other hand, the volume changes become small with an increase in the initial suction. And, the volumetric strain during shearing is independent of the confining pressure.