• Title/Summary/Keyword: ground stress behavior

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Flexural Behavior Evaluation of Two Types Fiber Reinforced Shotcrete using Round Panel Test (원형패널 시험을 활용한 두 종류 섬유 보강 숏크리트의 휨거동 평가)

  • Jeon, Chanki;Jeon, Joongkyu
    • Journal of the Society of Disaster Information
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    • v.11 no.4
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    • pp.607-614
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    • 2015
  • This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

Seismic Behavior of High-rise Steel Moment-resisting Frames with Vertical Mass Irregularity (수직질량 비정형이 존재하는 고층 강 모멘트-저항골조의 지진 거동)

  • Park, Byong-Jeong;Song, In-Hawn
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.1
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    • pp.1-15
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    • 2004
  • Dynamic analyses were carried out to study the seismic response of high-rise steel moment-resisting frames in sixteen story buildings. The frames are intentionally designed by three different design procedures; strength controlled design. strong column-weak beam controlled design. and drift controlled design. The seismic performances of the so-designed frames with vertical mass irregularities were discussed in view of drift ratio. plastic hinge rotation, hysteretic energy input and stress demand. A demand curve of hysteretic energy inputs was also presented with two earthquake levels in peak ground accelerations for a future design application.

Study on lateral resistance of steel-concrete composite drilled shafts by using 3D FEM (3차원 유한요소법을 이용한 강관합성 말뚝재료의 수평저항력 고찰)

  • Lee, Ju-Hyung;Shin, Hyu-Soung;Choi, Sang-Ho;Park, Jae-Hyun;Chung, Moon-Kyung;Kwak, Ki-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.683-690
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    • 2008
  • Steel-concrete composite columns are popular for superstructures of bridges, and the outside steel attached to the shaft increases the shaft resistance due to confining concrete. In this study, lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on numerical analysis when steel casings are used as structural elements like composite columns. Ultimate lateral resistance of composite drilled shafts with various diameters was numerically calculated through 3D finite element analysis. For that, elasto-plastic model with perfectly plasticity is involved to capture the ultimate load. A commercial FEM program, MIDAS-GTS, is used in this study. Real field conditions of the West Coast, Korea were considered to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for better understanding the mechanisms of the composite shaft behavior.

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Effects of Surface Deformation on Intergranular Oxidation of Alloy 600 (Alloy 600의 결정립계 산화에 대한 표면 변형의 영향)

  • Ha, Dong Woog;Lim, Yun Soo;Kim, Dong Jin
    • Corrosion Science and Technology
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    • v.19 no.3
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    • pp.138-145
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    • 2020
  • Immersion tests of Alloy 600 were conducted in simulated primary water environments of a pressurized water reactor at 325 ℃ for 10, 100, and 1000 h to obtain insight into effects of surface deformation on internal and intergranular (IG) oxidation behavior through precise characterization using various microscopic equipment. Oxidized samples after immersion tests were covered with polyhedral and filamentous oxides. It was found that oxides were abundant in mechanically ground (MG) samples the most. The number density of surface oxides increased with time irrespective of the method of surface finish. IG oxidation occurred in mechanically polished (MP) and chemically polished (CP) samples with thin internal oxidation layers. However, IG oxidation was suppressed with relatively thick internal oxidation layers in MG samples compared to MP and CP samples, suggesting that MG treatment could increase resistance to primary water stress corrosion cracking (PWSCC) from the standpoint of IG oxidation. As a result, appropriate surface treatment for Alloy 600 could prevent oxygen diffusion into grain boundaries, inhibit IG oxidation, and finally induce its high PWSCC resistance.

Mechanical Properties of Oil Pollution Sand Due to Changes in the Viscosity of Oil (점도 변화에 따른 유류오염 모래의 역학적 특성)

  • Hong, Seung Seo;Bae, Gu-Jin;Kim, YoungSeok
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.577-585
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    • 2015
  • Contamination of soil due to an oil spill influences its subsequent behavior. An investigation was conducted to study the effect of oil viscosity on compaction characteristics, coefficient of permeability, and shear strength. Water permeability was also determined by using Kerosene, Engine oil, and Crude-oil as contaminants. The test results indicate that the compaction characteristics are influenced by oil contamination. Direct shear test was conducted to investigate the effect of oil in the pore space in sandy ground. angle of internal friction of sand (based on total stress condition) decreases due to presence of oil within the pore spaces in sand.

Effect of progressive shear punch of a foundation on a reinforced concrete building behavior

  • Naghipour, Morteza;Niak, Kia Moghaddas;Shariati, Mahdi;Toghroli, Ali
    • Steel and Composite Structures
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    • v.35 no.2
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    • pp.279-294
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    • 2020
  • Foundation of a building is damaged under service loads during construction. First visit shows that the foundation has been punched at the 6 column's foot region led to building rotation. Foundation shear punching occurring has made some stresses and deflections in construction. In this study, progressing of damage caused by foundation shear punching and inverse loading in order to resolve the building rotation has been evaluated in the foundation and frame of building by finite element modeling in ABAQUS software. The stress values of bars in punched regions of foundation has been deeply exceeded from steel yielding strength and experienced large displacement based on software's results. On the other hand, the values of created stresses in the frame are not too big to make serious damage. In the beams and columns of ground floor, some partial cracks has been occurred and in other floors, the values of stresses are in the elastic zone of materials. Finally, by inverse loading to the frame, the horizontal displacement of floors has been resolved and the values of stresses in frame has been significantly reduced.

Comparison of MCC and SSC Models Based on Numerical Analysis of Consolidation Test (압밀시험의 수치해석에 의한 MCC 모델과 SSC 모델 비교)

  • Kwon, Byenghae;Eam, Sunghoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.66 no.2
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    • pp.1-12
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    • 2024
  • In order to integrate two consolidation theories of Terzaghi's consolidation theory and Mesri's secondary compression theory and to identify a model suitable for analyzing stress-strain behavior over time, numerical analysis on consolidation tests were conducted using a modified cam-clay model and a soft soil creep model and the following conclusions were obtained. The results of numerical analysis applying the theory that a linear proportional relationship is established between the void ratio at logarithmic scale and the permeability coefficient at logarithmic scale is better agreement with the result of oedometer test than the results of applying constant hydraulic conductivity. The modified cam-clay model is a model that does not include secondary compression, but the slope of the normal consolidation line corresponding to the compression index of the standard consolidation test includes secondary compression, so the actual settlement curve over time is lower than the predicted value through numerical analysis. It always gets smaller. Other previous studies that applied Terzaghi's consolidation theory to consolidation test analysis showed the same results and were cross-confirmed. The soft soil creep model, which includes secondary compression in the theory, showed good agreement in all sections including secondary compression in the consolidation test results. It was judged appropriate to use a soft soil creep model when performing numerical analysis of soft clay ground.

Numerical study on tunnel design for securing stability at connection between submerged floating tunnel and bored tunnel (수중터널 지반 접속부 안정성 확보를 위한 터널 설계에 대한 수치해석적 연구)

  • Kang, Seok-Jun;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.22 no.1
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    • pp.77-89
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    • 2020
  • Submerged floating tunnel (SFT) is a type of tunnel that allows tunnel segments to float underwater by buoyancy, and is being actively studied in recent years. When the submerged floating tunnel is connected to the ground, the tunnel and the bored tunnel inside the ground must be connected. There is risk that the stress will be concentrated at the connection between the two tunnels due to the different constraints and behavior of the two tunnels. Therefore, special design and construction methods should be applied to ensure the stability around the connection. However, previous studies on the stability at the connection site have not been sufficiently carried out, so study on the basic stage of the stability at connection site are necessary. In this study, numerical analysis simulating the connection between submerged floating tunnel and the bored tunnel confirmed that the shear strain concentration occurred in the ground around the connection, and it was analyzed that the structural factors can be handled during construction to have effects on the stability of the ground around the connection. Numerical results show that the risks from disproportionate displacements in the two tunnels can be mitigated through the construction of grouting material and joint design. Although the results from this study are qualitative results, it is expected that it will contribute to the determination of structural factors and risk areas that should be considered in the design of connections between the submerged floating tunnel and bored tunnel in the future studies.

A Study on the Mechanical and Rheological Properties of the Recycled Polyethylene Composites with Ground Waste Tire Powder (재생 폴리에틸렌/폐타이어 분말 복합체의 기계적 특성 및 유변학적 특성에 관한 연구)

  • Kye, H.;Shin, K.;Bang, D.
    • Elastomers and Composites
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    • v.41 no.2
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    • pp.97-107
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    • 2006
  • The recycled polyethylene composites with various ratio of ground waste tire powder were manufactured by using a fully intermeshing co-rotating twin screw extruder for the reuse of waste tire scrap. In this investigation, the ground waste tire powders (GWTP) were blended with virgin HDPE and recycled polyethylene in the weight ratio of 0 to 50 wt.%. Mechanical properties such as tensile strength, elongation at break and impact strength were measured by using ASTM standard. The experimental results for the various composite showed that the tensile strength of composites decreased with increasing GWTP ratio, while elongation at break increased with the amounts of GWTP. On the other hand, the impact strength for the three kinds of composites showed maximum at the 30 wt.% of GWTP and then decreased. Morphology of the fracture surface tends to be rough with increasing waste tire powder content. Rheological properties were investigated by measuring the shear viscosity against shear rates and softening temperatures. They showed that melt viscosity of rubber composites in this study subsequently increased with increasing GWTP content as a result of increase of flow resistance against external stress and followed a Power-law behavior.

Investigations of Application of Anchor Type Nail Using Experiments and Numerical Analysis (모형실험 및 수치해석을 이용한 앵커형 네일의 적용성 검토)

  • Kim, Donggun;Jeong, Gilsu;Jo, Kwangjun;Yoo, Namjae;Um, Jaekyung
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.11
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    • pp.19-26
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    • 2012
  • In the present study, anchor type nail with PC-strand which can add up the pre-stress at the nailing to increase the resistance and shear stress in the whole ground has been investigated. Load-displacement and wall displacement have been analyzed by experimental model and numerical analysis of anchor type nail, nailing, and non-nailing to examine the behavior of anchor type nail. From the experimental results, it was found that horizontal displacement is considerably decreased according to increasing the load in case of anchor type nail added pre-tension. Especially, it was observed that resistance of displacement at the upper wall is increased. The results of numerical analysis show the same results of experimental results.