• Title/Summary/Keyword: displacement constraints

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Optimum Design of Plane Frames Subject to Displacement and Stress Constraints (처짐과 응력제약(應力制約)을 받는 평면(平面) 뼈대의 최적설계(最適設計))

  • Chung, Young Shik;Lee, Jae Whane
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.1
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    • pp.23-31
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    • 1987
  • This work presents an optimality criteria method which gives accurate solution to the structural optimization problem of plane frames subject to displacement and stress constraints. The method is made efficient, as well as rigorous, by including only the lateral displacement of the top floor in the set of behavioral constraints. The bending stresses of members are treated as side constraints based on the concept of fully-stressed-design, but the optimality of the final design is tested by treating them as behavioral constraints and examining if the design satisfies this new optimality criteria. Worked examples show the superiority of the rigorous opimality criteria in spite of its being simple and efficient.

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Optimal Shape Design of Excavator Boom Using the Semi-Analytical Method (민감도 근사해석법을 이용한 굴삭기 붐의 최적형상설계)

  • Lim, O-Kaung;Cho, Heon
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.1
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    • pp.301-309
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    • 1995
  • Shape optimal design of an excavator boom to minimize weight can be formulated as a nonlinear programming problem with an automesh refinement carried out by using the finite element method. The design variables are the radii and the coordinates of the circle to describe the excavator boundary shape. In addition to the displacement and stress constraints, geometric constraints are imposed such that the nodes cannot cross the certain range. The optimum design is obtained by using the PLBA nonlinear programming code. The sensitivity derivatives are calculated using the semi-analytical scheme. Numerical results of an excavator boom show potential for weight reduction of 4.4%(65.6 kgf) when considering the displacement, stress and geometric constraints.

Dynamic Sensitivity Analysis For Lateral Drift Control Of Frame-Shear Wall Structures (골조-전단벽 구조물의 횡변위제어를 위한 동적 민감도 해석)

  • Lee, Han-Joo;Kim, Ji-Youn;Han, Seung-Baek;Nam, Kyung-Yun;Kim, Ho-Soo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.571-576
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    • 2007
  • This study presents stiffness-based optimal design to control quantitatively lateral drift of frame-shear wall structures subject to seismic loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also, the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. The 12 story frame-shear wall structural models is considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

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Displacement Measurement of Multi-Point Using a Pattern Recognition from Video Signal (영상 신호에서 패턴인식을 이용한 다중 포인트 변위측정)

  • Jeon, Hyeong-Seop;Choi, Young-Chul;Park, Jong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.675-680
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    • 2008
  • This paper proposes a way to measure the displacement of a multi-point by using a pattern recognition from video signal. Generally in measuring displacement, gab sensor, which is a displacement sensor, is used. However, it is difficult to measure displacement by using a common sensor in places where it is unsuitable to attach a sensor, such as high-temperature areas or radioactive places. In this kind of places, non-contact methods should be used to measure displacement and in this study, images of CCD camera were used. When displacement is measure by using camera images, it is possible to measure displacement with a non-contact method. It is simple to install and multi-point displacement measuring device so that it is advantageous to solve problems of spatial constraints.

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Displacement Measurement of Multi-point Using a Pattern Recognition from Video Signal (영상 신호에서 패턴인식을 이용한 다중 포인트 변위측정)

  • Jeon, Hyeong-Seop;Choi, Young-Chul;Park, Jong-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.12
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    • pp.1256-1261
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    • 2008
  • This paper proposes a way to measure the displacement of a multi-point by using a pattern recognition from video signal. Generally in measuring displacement, gab sensor, which is a displacement sensor, is used. However, it is difficult to measure displacement by using a common sensor in places where it is unsuitable to attach a sensor, such as high-temperature areas or radioactive places. In this kind of places, non-contact methods should be used to measure displacement and in this study, images of CCD camera were used. When multi-point is measure by using a pattern recognition, it is possible to measure displacement with a non-contact method. It is simple to install and multi-point displacement measuring device so that it is advantageous to solve problems of spatial constraints.

Study on the fire resistance of castellated composite beams with ortho-hexagonal holes and different beam-end constraints

  • Junli Lyu;Encong Zhu;Rukai Li;Bai Sun;Zili Wang
    • Steel and Composite Structures
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    • v.46 no.4
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    • pp.539-551
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    • 2023
  • In order to study the fire resistance of castellated composite beams with ortho-hexagonal holes and different beam-end restraints, temperature rise tests with constant load were conducted on full-scale castellated composite beams with ortho-hexagonal holes and hinge or rigid joint constraints to investigate the temperature distribution, displacement changes and failure patterns of castellated composite beams with two different beam-end constraints during the whole course of fire. The results show that (1) During the fire, the axial pressure and horizontal expansion deformation generated in the rigid joint constrained composite beam were larger than those in the hinge joint constrained castellated composite beam, and their maximum horizontal expansion displacements were 30.2 mm and 17.8 mm, respectively. (2) After the fire, the cracks on the slab surface of the castellated composite beam with rigid joint constraint were more complicated than hinge restraint, and the failure more serious; the lower flange and web at the ends of the castellated steal beams with hinge and rigid joint constraint produced serious local buckling, and the angles of the ortho-hexagonal holes at the support cracked; the welds at both ends of the castellated composite beam with rigid joint constraint cracked. (3) Based on the simplified calculation method of solid-web composite beam, considering the effect of holes on the web, this paper calculated the axial force and displacement of the beam-end constrained castellated composite beams under fire. The calculation results agreed well with the test results.

Quantitative Lateral Drift Control of RC Tall Frameworks using Dynamic Displacement Sensitivity Analysis (동적 변위민감도 해석을 이용한 고층 RC 골조구조물의 정량적인 횡변위 제어 방안)

  • Lee, Han-Joo;Kim, Ho-Soo
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.3 s.21
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    • pp.103-110
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    • 2006
  • This study presents a technique to control quantitatively lateral drift of RC tall frameworks subject to lateral loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. Three types of 10 and 50 story RC framework models are considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

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A Study on the Optimization of Steel Structures Considering Displacement Constraints (변위제약조건을 고려한 강구조물의 최적화에 관한 연구)

  • Kim, Ho Soo;Lee, Han Joo
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4 s.37
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    • pp.657-666
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    • 1998
  • This study presents an effective dual algorithm for the optimal design of steel structures with displacement constraints. The dual method can replace a primary optimization problem with a sequence of approximate explicit subproblems with a simple algebraic structure. Since being convex and separable, each subproblem can be solved efficiently by the dual method. Specifically, this study uses the principle of virtual work to obtain the displacement constraint equations with an explicit form and adds the linear regression equation expressing the relationships between the cross-section properties to the dual algorithm to reduce the number of design variables. Furthermore, this study deals with the discrete optimization problem to select members with the standard steel sections. Through numerical analyses, the proposed method will be compared with the conventional optimality criteria method.

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A Study on Stability for Traverse Cam of Twising Machine using Shape Design Method of Relative Velocity and Modified Displacement Curves (상대속도에 의한 형상설계법과 개선된 변위선도에 의한 연사기용 Traverse Cam의 안정성에 관한 연구)

  • Kim, Jong-Su;Yun, Ho-Eop
    • 연구논문집
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    • s.31
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    • pp.101-112
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    • 2001
  • A Twisting machine is to twist yarns for improving yarn stiffness. After twisting yarns, the twisting machine is winding yarn at a bobbin. Traverse cam is main part of winding yarn part. In other to improve twisting machine performance and stability, improve traverse cam part. Original displacement curves of traverse cam has two problems. One is that displacement curve has a vertex point the other is that velocity curve is discontinue point. So that, in this paper proposes a modified displacement curves of traverse cam and new shape design method of the traverse cam using the relative velocity method[1]. The relative velocity method calculates the relative velocity of the follower versus the cam at a center of roller, and then determines a contact point by using the geometric relationship and the kinematical constraints. Finally, we present to compare two designed cam. One is designed using original displacement curves the other is using modified displacement curve.

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An Optimality Criteria applied to The Plane Frames (평면 뼈대 구조물에 적용된 최적규준)

  • 정영식;김창규
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.10a
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    • pp.17-24
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    • 1995
  • This work proposes an optimality criteria applicable to the optimum design of plane frames. Stress constraints as well as displacement constraints are treated as behavioural constraints and thus the first order approximation of stress constraints is adopted. The design space of practical reinforced concrete frames with discrete design variables has been found to have many local minima, and thus it is desirable to find in advance the mathematical minimum, hopefully global, prior to starting to search a practical optimum design. By using the mathematical minimum as a trial design of any search algorithm, we may not full into a local minimum but apparently costly design. Therefore this work aims at establishing a mathematically rigorous method ⑴ by adopting first-order approximation of constraints, ⑵ by reducing the design space whenever minimum size restrictions become "active" and ⑶ by the of Newton-Raphson Method.

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