• Title/Summary/Keyword: plastic rotation

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Earth Pressure Distribution with Rigid Retaining Wall Movements (강성토유벽의 움직임에 따른 토압분포)

  • 강병희;채승호
    • Geotechnical Engineering
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    • v.5 no.1
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    • pp.47-60
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    • 1989
  • Lateral earth Pressure distributions due to the ,randy soil backfill behind the rigid vertical walls for three different wall movement modes are obtained by the elasto-plastic finite element analys of soil deformation, and these earth pressures are compared with both Rankine's and Dubrova's active earth pressures. Thereby, the effects of the magnitude and the mode of wall displacement on the earth pressure distribution are investigated. Three different modes of wall movement considered in this study are the rotation about bottom, the rotation about top and the translation. For the case of the wall rotation about top, the earth pressure distribution is shown as a reverse S-curve-shaped distribution due to the arching effect. Consequently, the point of application of the lateral thrust is much higher than one-third of the wall height from the base. And, comparing the other modes of wall movement, the magnitude and the point of appliestion of the lateral thrust for the wall rotation about top are larger and higher, respectively. The wedge-shaped plastic zone in the backfill at active failure is developed only for the mode of wall rotation about bottom. The lateral earth pressure distributions on the walls with inclined backfill of several different slopes are shown for the mode of wall rotation about bottom.

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Seismic Performance Evaluation of Beam-Column Connection for Panel Zone Strength (패널존의 강도비에 따른 기둥-보 접합부의 내진성능 평가)

  • Kim, Sung-Young;Shin, Chang-Hoon
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.1 s.24
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    • pp.11-20
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    • 2007
  • The study proposes the method to cancel the scallop to avoid fracture of the circumstance of the scallop at H shape column-to-beam connection and reinforce at beam flange two faces with the cover plates and rib. A total of four specimens were tested to enhance seismic performance of building structure by reducing the frequency of stress concentration and preventing the brittle fracture of scallop. For this purpose, four full-scale test specimens were made and loaded with quasi-static reversed cyclic loading. The main analytical parameters are panel-zone-strength ratio, yield strengths, initial stiffness, total plastic rotation, contribution of each element to total plastic rotation and energy dissipation capability. For the specimens tested under repeated loading, the experimental result was satisfied with seismic performance requirement as the Special Moment Frames (SMF). The analysis results show that all of the test specimens were found to have good performance to 4% story drift and satisfied the criteria for the plastic roation capacity of SMFs that is 0.03 rad. according to the 1997 AISC seismic provision.

Redistribution of Negative Moments in Beams Subjected to Lateral Load (횡하중에 대한 휨재의 부모멘트 재분배)

  • Eom, Tae-Sung
    • Journal of the Korea Concrete Institute
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    • v.23 no.6
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    • pp.731-740
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    • 2011
  • Provisions for the redistribution of negative moments in KCI 2007 and ACI 318-08 use a method for continuous flexural members subjected to uniformly-distributed gravity load. Moment redistributions and plastic rotations in beams of reinforced concrete moment frames subjected to lateral load differ from those in continuous flexural members due to gravity load. In the present study, a quantitative relationship between the moment redistribution and plastic rotation is established for beams subjected to both lateral and gravity loads. Based on the relationship, a design method for the redistribution of negative moments is proposed based on a plastic rotation capacity. The percentage change in negative moments in the beam was defined as a function of the tensile strain of re-bars at the section of maximum negative moment, which is determined by a section analysis at an ultimate state using KCI 2007 and ACI 318-08. Span, reinforcement ratio, cracked section stiffness, and strain-hardening behavior substantially affected the moment redistribution. Design guidelines and examples for the redistribution of the factored negative moments determined by elastic theory for beams under lateral load are presented.

A Study on the Rotation-Induced Birefringence in Plastic Disk Substrate (회전에 의해 플라스틱 기판에 추가로 발생하는 복굴절의 측정에 관한 연구)

  • 김종선;윤경환
    • Transactions of Materials Processing
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    • v.12 no.8
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    • pp.730-737
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    • 2003
  • Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical disk substrate Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. However, high speed rotation also induces extra stresses and birefringence in real operation of disk drives. In the present paper rotation-induced in-plane birefringence has been measured and presented for CD and DVD substrates at different radial position. About 10 - 15 nm of extra retardation in one pass has been measured up to 4,800 rpm. The distribution of extra rotation-induced birefringence will be valuable data for designing an optimal optical disk substrate. Finally, experimental results were compared with the extra stresses calculated from simple formulation.

Anisotropic Constitutive Model at Large Viscoplastic Deformations (탄소성 대변형에 관한 비등방 구성방정식)

  • Cho, Han-Wook
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.10a
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    • pp.178-184
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    • 1995
  • A new combined isotropic/kinematic and orthotropic hardening viscoplastic model is proposed which can account for not only differential orientations but also preferred orientations of grains in n metal at finite plastic deformations with an introduction of multiple spin (rate of rotation) concept within the general framework of the model, the effects of anisotropy and constitutive spins will be discussed in conjunction with a closed-form solution for simple shear in n rigid-plastic material, which will be used to simulate experimental data of Montheillet, et al. (1984) for fixed-end tortion tests at finite plastic deformations.

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An Introduction to the Septal Extension Graft

  • Kim, Myung-Hoon;Choi, Jeong-Hwan;Kim, Min-Su;Kim, Seok-Kwun;Lee, Keun-Cheol
    • Archives of Plastic Surgery
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    • v.41 no.1
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    • pp.29-34
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    • 2014
  • The septal extension graft is a very useful method of controlling nasal lengthening and tip projection, rotation, and shape by fixing a graft to the septum, which leads to a strong supporting structure. Enhancing graft stability is important for better long-term outcomes and minimizing complications or relapse, and even more efficient application of these methods is needed for East Asians who lack enough cartilage to be harvested in addition to possessing a weak cartilage framework. In this paper, the methods for overcoming the drawbacks of the septal extension graft, such as instability, a fixed tip, and insufficiency of cartilage, are presented, and the applications of each method for greater satisfaction with surgical outcomes are also discussed.

Finite Element Analysis of Elasto-Plastic Large Deformation considering the Isotropic Damage(the 2nd Report) (등방성손상을 고려한 탄소성 대변형 무제의 유한요소해석(제2보))

  • 이종원
    • Journal of Ocean Engineering and Technology
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    • v.14 no.2
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    • pp.76-83
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    • 2000
  • this paper was concentrated on the finite element formulation to solve boundary value problems by using the isotropic elasto-plastic damage constitutive model proposed previously(Noh, 2000) The plastic damage of ductile materials is generally accompanied by large plasticdeformation and strain. So nonlinearity problems induced by large deformation large rotation and large strain behaviors were dealt with using the nonlinear kinematics of elasto-plastic deformations based on the continuum mechanics. The elasto-plastic damage constitutive model was applied to the nonlinear finite element formulation process of Shin et al(1997) and an improved analysis model considering the all nonlinearities of structural behaviors is proposed. Finally to investigate the applicability and validity of the numerical model some numerial examples were considered.

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Evaluation of Rotation Capacity of Steel Moment Connections ConsideringInelastic Local Buckling - Parametric Studies (비탄성 국부좌굴을 고려한 철골 모멘트 접합부의 회전능력에 대한 변수 연구)

  • Lee, Kyung Koo
    • Journal of Korean Society of Steel Construction
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    • v.20 no.5
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    • pp.625-632
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    • 2008
  • In the companion paper (Model Development), an analytical model estimating the available rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames was proposed. In this paper, two limit states were considered as the connection rotation capacity criteria: (i) strength degradation failure when the strength falls below the nominal plastic strength due to the local buckling of the beam's cross-section and (ii) low-cycle fatigue fracture caused by plastic strain accumulation at the buckled flange after only a few cycles of high-amplitude deformation. A series of analyses are conducted using the proposed model with two limit states under monotonic and cyclic loadings. Beam section geometric parameters, such as flange and web slenderness ratios, varied over the practical ranges of H-shapedbeams to observe their effect on the rotation capacity and low-cycle fatigue life of pre-qualified WUF-W connections.

Post-operative Stability of Counter Clockwise Rotation of the Mandibular Plane in Skeletal CIII with Anterior Openbite Patients (전치부 개교합을 가진 골격성 3급 부정교합 환자에서 하악의 반시계 방향 회전 시 술 후 안정성)

  • Ryu, Jeong-Min;Ryu, Kyung-Sun;Lee, Baek-Soo;Kwon, Yong-Dae;Choi, Byung-Joon;Kim, Yeo-Gab;Ohe, Joo-Young;Park, Seong-Won
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.34 no.4
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    • pp.252-259
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    • 2012
  • Purpose: This study evaluated the postoperative stability of counter clockwise rotation of the mandibular plane in anterior openbite patients, who have had one jaw surgery performed. Methods: This study includes patients with skeletal class III malocclusion accompanied by anterior openbite among the patients who have had BSSRO performed, resulting in counter clockwise rotation of the mandibule. We excluded the patients with genioplasty and segmental surgery, and included 23 patients who underwent BSSRO. Results: We found no statistical significance between the amount of counter clockwise rotation in the mandible in the Pearson correlation test. Also, there was no significant difference between Group 1 (< $3^{\circ}$) and Group 2 (> $3^{\circ}$). Conclusion: This study evaluated the amount of horizontal relapse, and the degree of relapse. Stable results were obtained. Although there was no statistical significance between the degree of openbite and the amount of horizontal relapse, the group with a greater amount of openbite had a greater amount of relapse.