• Title/Summary/Keyword: optimization technique

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A multi-parameter optimization technique for prestressed concrete cable-stayed bridges considering prestress in girder

  • Gao, Qiong;Yang, Meng-Gang;Qiao, Jian-Dong
    • Structural Engineering and Mechanics
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    • v.64 no.5
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    • pp.567-577
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    • 2017
  • The traditional design procedure of a prestressed concrete (PC) cable-stayed bridge is complex and time-consuming. The designers have to repeatedly modify the configuration of the large number of design parameters to obtain a feasible design scheme which maybe not an economical design. In order to efficiently achieve an optimum design for PC cable-stayed bridges, a multi-parameter optimization technique is proposed. In this optimization technique, the number of prestressing tendons in girder is firstly set as one of design variables, as well as cable forces, cable areas and cross-section sizes of the girders and the towers. The stress and displacement constraints are simultaneously utilized to ensure the safety and serviceability of the structure. The target is to obtain the minimum cost design for a PC cable-stayed bridge. Finally, this optimization technique is carried out by a developed PC cable-stayed bridge optimization program involving the interaction of the parameterized automatically modeling program, the finite element structural analysis program and the optimization algorithm. A low-pylon PC cable-stayed bridge is selected as the example to test the proposed optimization technique. The optimum result verifies the capability and efficiency of the optimization technique, and the significance to optimize the number of prestressing tendons in the girder. The optimum design scheme obtained by the application can achieve a 24.03% reduction in cost, compared with the initial design.

Study of Hybrid Optimization Technique for Grain Optimum Design

  • Oh, Seok-Hwan;Kim, Yong-Chan;Cha, Seung-Won;Roh, Tae-Seong
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.4
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    • pp.780-787
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    • 2017
  • The propellant grain configuration is a design variable that determines the shape and performance of a solid rocket motor. Grain configuration variables have complicated effects on the motor performance; so the global optimization problem has to be solved in order to design the configuration variables. The grain performance has been analyzed by means of the grain burn-back and internal ballistic analysis, and the optimization technique searches for the configuration variables that satisfy the requirements. The deterministic and stochastic optimization techniques have been applied for the grain optimization, but the results are imperfect. In this study, the optimization design of the configuration variables has been performed using the hybrid optimization technique, which combines those two techniques. As a result, the hybrid optimization technique has proved to be efficient for the grain optimization design.

A study on the extremely light trailer frame using topology optimization technique (위상최적설계기법을 이용한 초경량 트레일러 연구)

  • Yoon, Min-Su;Jang, Gang-Won;Park, Jae-Ha
    • Proceedings of the KSME Conference
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    • pp.410-411
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    • 2008
  • A topology optimization technique to develop extremely light trailer frame structure is performed due to the strong needs of the customers and makers owing to high level of oil price. First, the overall layout of the frame is derived using topology optimization and then, final specification is also derived utilizing DOE optimization technique for mass product.

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Numerical Verification of Hybrid Optimization Technique for Finite Element Model Updating (유한요소모델개선을 위한 하이브리드 최적화기법의 수치해석 검증)

  • Jung, Dae-Sung;Kim, Chul-Young
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.6
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    • pp.19-28
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    • 2006
  • Most conventional model updating methods must use mathematical objective function with experimental modal matrices and analytical system matrices or must use information about the gradient or higher derivatives of modal properties with respect to each updating parameter. Therefore, most conventional methods are not appropriate for complex structural system such as bridge structures due to stability problem in inverse analysis with ill-conditions. Sometimes, moreover, the updated model may have no physical meaning. In this paper, a new FE model updating method based on a hybrid optimization technique using genetic algorithm (GA) and Holder-Mead simplex method (NMS) is proposed. The performance of hybrid optimization technique on the nonlinear problem is demonstrated by the Goldstein-Price function with three local minima and one global minimum. The influence of the objective function is evaluated by the case study of a simulated 10-dof spring-mass model. Through simulated case studies, finally, the objective function is proposed to update mass as well as stiffness at the same time. And so, the proposed hybrid optimization technique is proved to be an efficient method for FE model updating.

Stiffness Determination of a Bolted Member Using Optimization Technique (최적화 기법을 이용한 모울트 체결체의 강성 평가)

  • 김태완;손용수;박성호
    • Computational Structural Engineering
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    • v.6 no.4
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    • pp.99-105
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    • 1993
  • In this paper a useful method on evaluating the joint stiffness of a bolted member was introduced using optimization technique on the basis of Finite Element Method. A finite element model having one directional gap element at boundary area was introduced to compensate the prying force in jointed members which might be caused by geometrical configuration of members. Results showed a good agreement with classical method in certain range and will be available to define the appropriate design margin of pre-load design.

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Topology Optimization of Plane Structures using Modal Strain Energy for Fundamental Frequency Maximization

  • Lee, Sang-Jin;Bae, Jung-Eun
    • Architectural research
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    • v.12 no.1
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    • pp.39-47
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    • 2010
  • This paper describes a topology optimization technique which can maximize the fundamental frequency of the structures. The fundamental frequency maximization is achieved by means of the minimization of modal strain energy as an inverse problem so that the strain energy based resizing algorithm is directly used in this study. The strain energy to be minimized is therefore employed as the objective function and the initial volume of structures is used as the constraint function. Multi-frequency problem is considered by the introduction of the weight which is used to combine several target modal strain energy terms into one scalar objective function. Several numerical examples are presented to investigate the performance of the proposed topology optimization technique. From numerical tests, it is found to be that the proposed optimization technique is extremely effective to maximize the fundamental frequency of structure and can successfully consider the multi-frequency problems in the topology optimization process.

Design of the Spacers Arrangement for Field Emission Displays using Topology Optimization Technique (위상 최적화 기법을 잉요한 FED용 스페이서의 배치 설계)

  • Chung, Tae-Eun
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.11
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    • pp.49-54
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    • 2000
  • A field emission display has spacers separating the emitting base and display face. The arrangement of the spacer is important for maintenance of required clearance, endurance of bending stresses, and efficient vacuum sealing. Topology optimization technique with material density was introduced to select the best position of the spacers from the available positions. The displacement and Von Mises stress distribution of the panels with optimal spacers were calculated by finite element method. Also the design guide for adding eliminating spacers was proposed.

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A Sequential Approximate Optimization Technique Using the Previous Response Values (응답량 재사용을 통한 순차 근사최적설계)

  • Hwang Tae-Kyung;Choi Eun-Ho;Lim O-Kaung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.1
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    • pp.45-52
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    • 2005
  • A general approximate optimization technique by sequential design domain(SDD) did not save response values for getting an approximate function in each step. It has a disadvantage at aspect of an expense. In this paper, previous response values are recycled for constructing an approximate function. For this reason, approximation function is more accurate. Accordingly, even if we did not determine move limit, a system is converged to the optimal design. Size and shape optimization using approximate optimization technique is carried out with SDD. Algorithm executing Pro/Engineer and ANSYS are automatically adopted in the approximate optimization program by SDD. Convergence criterion is defined such that optimal point must be located within SDD during the three steps. The PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm is used to solve approximate optimization problems. This algorithm uses the second-order information in the direction finding problem and uses the active set strategy.

An Optimization Method for Self-Boring Pressuremeter Holding Test to Determine a Horizontal Coefficient of Consolidation under Partial Drained Soil Conditio (부분배수가 발생하는 지반의 수평압밀계수 결정을 위한 자가굴착식 프레셔메터 유지시험의 최적화 해석법)

  • Kim, Young-Sang
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.370-375
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    • 2005
  • This paper describes a systematic way of identifying the horizontal coefficient of consolidation for clayey soil under undrained condition and silty soil under partial drained condition by applying an optimization technique to the early part of dissipation data measured from the self-boring pressuremeter strain holding test. An analytical solution developed by Randolph & Wroth (1979) was implemented in normalized form to express the build-up and dissipation of excess pore pressures around a pressuremeter as a function of the rigidity index. Horizontal coefficient of consolidation was determined by minimizing the differences between theoretical and measured excess pore pressure curves using optimization technique. It was found that the proposed optimization technique can evaluate in-situ horizontal coefficient of consolidation rationally, which is similar with that obtained from the piezocone dissipation test. Furthermore, proposed method can evaluate appropriate coefficient of consolidation for soil under partially drained condition.

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