• Title/Summary/Keyword: thickness-shear

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Thin-Plate-Type Embedded Ultrasonic Transducer Based on Magnetostriction for the Thickness Monitoring of the Secondary Piping System of a Nuclear Power Plant

  • Heo, Taehoon;Cho, Seung Hyun
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1404-1411
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    • 2016
  • Pipe wall thinning in the secondary piping system of a nuclear power plant is currently a major problem that typically affects the safety and reliability of the nuclear power plant directly. Regular in-service inspections are carried out to manage the piping system only during the overhaul. Online thickness monitoring is necessary to avoid abrupt breakage due to wall thinning. To this end, a transducer that can withstand a high-temperature environment and should be installed under the insulation layer. We propose a thin plate type of embedded ultrasonic transducer based on magnetostriction. The transducer was designed and fabricated to measure the thickness of a pipe under a high-temperature condition. A number of experimental results confirmed the validity of the present transducer.

An analytical approach for aeroelastic analysis of tail flutter

  • Gharaei, Amin;Rabieyan-Najafabadi, Hamid;Nejatbakhsh, Hossein;Ghasemi, Ahmad Reza
    • Advances in Computational Design
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    • v.7 no.1
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    • pp.69-79
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    • 2022
  • In this research, the aeroelastic instability of a tail section manufactured from aluminum isotropic material with different shell thickness investigated. For this purpose, the two degrees of freedom flutter analytical approach are used, which is accompanied with simulation by finite element analysis. Using finite element analysis, the geometry parameters such as the center of mass, the aerodynamic center and the shear center are determined. Also, by simulation of finite element method, the bending and torsional stiffnesses for various thickness of the airfoil section are determined. Furthermore, using Lagrange's methods the equations of motion are derived and modal frequency and critical torsional/bending modes are discussed. The results show that with increasing the thickness of the isotropic airfoil section, the flutter and divergence speeds increased. Compared of the obtained results with other research, indicates a good agreement and reliability of this method.

Investigation of Shear Design Expressions of Large-Diameter Concrete-Filled Steel Tubes(CFT) (대구경 콘크리트 충전형 합성기둥의 전단 설계식 분석)

  • Jung, Eun Bi;Yeom, Hee Jin;Yoo, Jung Han
    • Journal of Korean Society of Steel Construction
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    • v.27 no.4
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    • pp.399-410
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    • 2015
  • Concrete filled steel tube(CFT) has outstanding deformation capacity and strength in comparison with reinforced concrete or steel tube. CFT drilled shaft, which is developed large shear force due to seismic load and soil liquefaction, is designed as large diameter. However, shear design equations of the current standards do not consider bond stress of CFT and it results in extremely conservative design. Currently, previous studies for improving shear equations scarcely exist and are impossible applied to large CFT drilled shafts since these studies focus on only small scale experimental research. In this study, eventually to propose improving shear equation of large diameter CFT, it is preliminary research to compare and investigate the previous studies and current standards.

An Experimental Study on the Shear Behavior of Reinforced Concrete Beams Strengthened with Slit Type Steel Plates (Slit형(形) 강판으로 보강(補强)한 철근콘크리트 보의 전단거동에 관한 실험연구)

  • Lee, Choon-Ho;Shim, Jong-Seok;Kwon, Ki-Hyuk
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.4
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    • pp.1-8
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    • 2008
  • RC beam of existing structures often encounter shear problems for various reasons. The shear failure of RC beam is sudden and brittle. Strengthening technique jacketing with external bonding of steel plates(or CFRP and CFS) with epoxy is many use to in practice. This study presents test results on strengthening shear deficient RC beams by external bonding of slit type steel plates. Test parameters are width, interval, length, thickness and angle of slit in steel plates. The purpose was to evaluate the reinforcing effects, failure modes and shear capacities for RC beams of strengthened with various slit type steel plates. The test result confirmed that all slit steel plates improved the stiffness and strength of the specimens significantly. Failure modes of SV series and SD series showed shear fractures and flexure fractures at ultimate state respectively. SD series were ductile rather than SV series.

Assessment of Shear Band Characteristics in Granular Soils Using Digital Image Analysis Technique for Plane Strain Tests (평면변형률 시험에서 이미지 해석을 통한 사질토의 전단면 특성 평가)

  • Jang, Eui-Ryong;Jung, Young-Hoon;Kim, Jun-Young;Chung, Choong-Ki
    • Journal of the Korean Geotechnical Society
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    • v.27 no.4
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    • pp.51-65
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    • 2011
  • Shear banding, the localization of deformation into thin zones, has a quite practical relevance, as stability and deformation characteristics of earth structures are controlled by the soil behavior within the shear band. In this study, for understanding occurrence and developed pattern of shear band, plane strain compression tests were performed on three soils with different particle-size distribution under various conditions. Digital images were captured during the experiments; then, deformation of a specimen was evaluated by digital image analysis technique. The characteristics of a shear band were evaluated from the state shortly after post-peak occurrence to critical state. Additionally, the statistical procedure was developed to determine the reasonable thickness of a shear band.

Development of Connection Details for a Double Split Tee Connection Without a Shear Tab (전단탭이 없는 상·하부 스플릿 티 접합부의 접합부상세 개발)

  • Yang, Jae Guen;Kim, Yong Boem
    • Journal of Korean Society of Steel Construction
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    • v.28 no.1
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    • pp.53-64
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    • 2016
  • The double split tee connection, a type of beam-to-column moment connection, exhibits different behavioral characteristics according to changes in the thickness of the T-stub flange, the gauge distance of the high-strength bolt, and the number and diameter of high-strength bolts. In general, the double split tee connection is idealized and designed so that a T-stub fastened to the top and bottom supports a flexural moment, and a shear tab supports a shear force. However, if the double split tee connection is applied to low-and medium-rise steel structures, the size of the beam member becomes small, and thus the shear tab cannot be bolted to the web of a beam. In this regard, this study was conducted to propose connection details to ensure that the double split tee connection with a geometric shape can display sufficient shear resisting capacity. To this end, experiments were conducted using full-scale specimens for the double split tee connection.

Elastic Shear Buckling Characteristics of Circularly Corrugated Plates (원형 파형 판의 탄성전단좌굴 특성)

  • Han, Taek Hee;Lim, Nam Hyoung;Park, Nam Hoi;Kang, Young Jong
    • Journal of Korean Society of Steel Construction
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    • v.14 no.4
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    • pp.529-538
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    • 2002
  • Applications of corrugated plates (or folded plates) have been recently increasing due to certain economic and structural advantages. Likewise, applications of corrugated plates has been increasing because they are stronger compared to flat plates. Therefore, specifications of corrugated plates should be determined. There are many design details in almost every specification for flat plates. However, except the bending strength and the normal strength, there are no detailed design guides such as shear strength. Thus, it is difficult for engineers to design structures consisting of corrugated plates. As such, engineers need a guide in designing corrugated plates. Extensive numerical study was conducted in order to identify the relationship between the shear strength and geometric conditions for corrugated plates. An eight-node thin shell element (QSL8) of the commercial program LUSAS (version 13.2) was used. The study was able to come up with a formula that helps determine the shear strength of corrugated plates under various geometric conditions, the size of corrugation, the curvature of corrugation, and the thickness of the corrugated plate. Likewise, corrugated plates were found to have a higher shear buckling strength than flat plates.

Design of a Steel Structural Building Using Double Split Tee Connections without Shear Tabs (전단탭이 없는 상·하부 스플릿 티 접합부를 적용한 강구조물의 설계)

  • Yang, Jae Guen;Kim, Yong Boem
    • Journal of Korean Society of Steel Construction
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    • v.28 no.2
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    • pp.85-96
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    • 2016
  • Double split tee connection has various strength, stiffness, and energy dissipation capacity according to changes of thickness of T-stub flange and gauge distance, number, and diameter of high-strength bolt. If the double split tee connection is applied to a low- or medium-rise steel structure, a shear tab can't be applied for supporting shear force because of geometrical limitation. So it is required to propose details of improved double split tee connection to support shear force as well as flexural force. This research was performed to see if enough rotational stiffness is found when the double split tee connection without shear tab which was obtained through analytic and experimental researches by Yang et al. is applied to a low- or medium-rise steel structure. Also, it was seen if the low- or medium-rise steel structure having double split tee connection without shear tab has safe structural behavior, as well as material saving effect.

Stiffness-based Optimal Design of Shear Wall-Frame Structure System using Sensitivity Analysis (민감도 해석을 이용한 전단벽-골조 구조시스템의 강성최적설계)

  • Lee Han-Joo;Kim Ho-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.1 s.71
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    • pp.63-71
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    • 2006
  • This study presents the effective stiffness-based optimal technique to control Quantitatively lateral drift for shear wall-frame structure system using sensitivity analysis. To this end, the element stiffness matrices are constituted to solve the compatibility problem of displacement degree of freedom between the frame and shear wall. Also, lateral drift constraint to introduce the approximation concept that can preserve the generality of the mathematical programming and can effectively solve the large scaled problems is established. And, the section property relationships for shear wall and frame members are considered in order to reduce the number of design variables and differentiate easily the stiffness matrices. Specifically, constant-shape assumption which is uniformly varying in size during optimal process is applied in frame structure. The thickness or length of shear wall can be changed depending on user's intent. Two types of 20 story shear wall-frame structure system are presented to illustrate the features of the stiffness-based optimal design technique.

Incipient motion criteria of uniform gravel bed under falling spheres in open channel flow

  • Khe, Sok An;Park, Sang Deog;Jeon, Woo Sung
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.149-149
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    • 2018
  • Prediction on initial motion of sediment is crucial to evaluate sediment transport and channel stability. The condition of incipient movement of sediment is characterized by bed shear stress, which is generated from force of moving water against the bed of the channel, and by critical shear stress, which depends on force resisting motion of sediment due to the submerged weight of the grains. When the bed shear stress exceeds the critical shear stress, sediment particles begin rolling and sliding at isolated and random locations. In Mountain River, debris flow frequently occurs due to heavy rainfall and can lead some natural stones from mountain slope into the bed river. This phenomenon could add additional forces to sediment transport system in the bed of river and also affect or change direction and magnitude of sediment movement. In this paper, evaluations on incipient motion of uniform coarse gravel under falling spheres impacts using small scale flume channel were conducted. The drag force of falling spheres due to water flow and length movement of falling spheres were investigated. The experiments were carried out in flume channel made by glass wall and steel floor with 12 m long, 0.6 m wide, and 0.6 m deep. The bed slopes were selected with the range from 0.7% to 1.5%. The thickness of granular layer was at least 3 times of diameter of granular particle to meet grain placement condition. The sphere diameters were chosen to be 4cm, 6 cm, 8 cm, 10 cm. The spheres were fallen in to the bed channel for critical condition and under critical condition of motion particle. Based on the experimental results, the Shields curve of particles Reynold number and dimensionless critical shear stress were plotted. The relationship between with drag force and the length movement of spheres were plotted. The pathways of the bed material Under the impact of spheres falling were analyzed.

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