• Title/Summary/Keyword: Reliability-Based Optimum Design

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A Study on Reliability Based Design Optimization For Thin Walled Beam Structures (박판보 구조물의 신뢰성 최적 설계에 관한 연구)

  • Lee, Sun-Byung;Yim, Hong-Jae;Baik, Serl
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.414-419
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    • 2001
  • In this research, reliability based optimum design is presented for the thin walled beam structures. Deterministic and stochastic optimum design are compared for the thin walled beam structures. Monte Carlo simulation is used for stochastic optimum design with consideration of probabilistic distribution of representative section properties of the thin walled beams with the Response Surface Method.

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Optimum Reliablity Based Design Criteria for Bridge Cassion Foundation (교량케이슨기초의 최적신뢰성 설계 규준)

  • 손용우;신형우;이증빈;정철원
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1992.10a
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    • pp.79-89
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    • 1992
  • This study is directed to propose a stability analysis and Design Criteria for Bridge Caisson foundations, with Could possibly replace the traditionals W.S.D. provisions of the Current Code, based on the FBOR(Load Factors based on optimum Reliability). The optimum reliability indices(Vertical bearing Capacity : $\beta$opt : 3.19, Lateral bearing Capacity : $\beta$opt= 3.15(ordinary), $\beta$opt : 2.93 (earthquake), Shearing resistance Capacity ; $\beta$opt : 2.87) are Selected as optimal Values Considering our practice base on the Calibration with the current Bridge Caisson foundation design Safety provisions, Load and resistance factors are measure by Using the proposed uncertainties and the Selected optimum reliability indices. furthermore, a set of nominal safety factors are proposed for the U.S.D. design provisions.

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Reliability Based Design Optimization for Section Shape of Simple Structures (빔 단면형상에 대한 구조물 신뢰성 최적설계)

  • 임준수;임홍재;이상범;허승진
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.672-676
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    • 2002
  • In this paper, a reliability-based design optimization method, which enables the determination of optimum design that incorporate confidence range for structures, is studied. Response surface method and Monte Carlo simulation are utilized to determine limit state function. The proposed method is applied to the I-type steel structure for reliability based optimal design.

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An efficient method for reliable optimum design of trusses

  • Dizangian, Babak;Ghasemi, Mohammad Reza
    • Steel and Composite Structures
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    • v.21 no.5
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    • pp.1069-1084
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    • 2016
  • This paper introduces a new and effective design amplification factor-based approach for reliable optimum design of trusses. This paper may be categorized as in the family of decoupled methods that aiming for a reliable optimum design based on a Design Amplification Factor (DAF). To reduce the computational expenses of reliability analysis, an improved version of Response Surface Method (RSM) was used. Having applied this approach to two planar and one spatial truss problems, it exhibited a satisfactory performance.

Reliability-Based Optimum Design for Tubular Frame Structures (골조 파이프 구조물의 최적신뢰성 설계)

  • 백점기
    • Journal of Ocean Engineering and Technology
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    • v.2 no.1
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    • pp.95-105
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    • 1988
  • This paper describes the development of a reliability-based optimum design technique for such three dimensional tubular frames as off shore structures. The objective function is formulated for the structural weight. Constraints that probability of failure for the critical sections does not exceed the allowable probability of failure are set up. In the evaluation of the probability of failure, fatigue as well as buckling and plasticity failure are taken into account and the mean-value first-order second-moment method(MVFOSM) is applied for its calculation. In order to reduce the computing time required for the repeated structural analysis in the optimization process, reanalysis method is also applied. Application to two and three dimensional simple frame structures is performed. The influence of material properties, external forces, allowable failure probabilities and interaction between external forces on the optimum design is investigated.

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Reliability-Based Optimum Design of High-Speed Railway Steel Bridges Considering Bridge/Rail Longitudinal Analysis and Bridge/Vehicle Dynamic Effect (교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려한 고속철도 강교량의 신뢰성 최적설계)

  • Lee, Jong-Soon;Ihm, Yeong-Rok
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.974-982
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    • 2009
  • To improve the effectiveness and economics the bridge design methodology considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect suggested in this study. The reliability-based Life-Cycle Costs(LCC) effective optimum design is applied to a 2-main steel girder bridge, 5$\times$(1@50m) for comparison with conventional design, initial cost optimization and equivalent LCC optimization. As a result of the optimum design based on reliability, it may be stated that the design of High-Speed railway bridges considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect are more efficient than typical existing bridges and LCC optimization without respect to bridge/rail longitudinal analysis and bridge/vehicle dynamic effect. The result of optimization design considering the interaction, design methodology suggested in this study, is higher than result of initial cost optimization design in initial cost, but that has the advantage than result of initial cost optimization design in expected LCC.

A Study on the Reliability-Based Optimum Design of Reinforced Concrete Frames (철근(鐵筋)콘크리트 뼈대구조(構造) 신뢰성(信賴性) 최적설계(最適設計)에 관한 연구(硏究))

  • Kim, Kee Dae;Yang, Chang Hyun;Cho, Hyo Nam
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.9 no.3
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    • pp.57-64
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    • 1989
  • This study presents a reliability-based optimum design of reinforced concrete frames, in which the AFOSM and SOSM methods are applied for the evaluation of the failure probabilities, and the sequential linear programming method is used as a practical approach to the system optimization. One-story two-bay reinforced concrete frame is chosen for the numerical illustration of the proposed reliability-based optimum design. As a result, it is found that the proposed procedure for the reliability-based optimization of RC frames could provide the accurate estimation of the optimal level of safety, and appears applicable to real structures with reasonable complexity. It is shown in the paper that the probability distributions of the basic random variables and the uncertainties of the applied loadings and material strengths may have great effect on the optimum design, but the AFOSM and SOSM methods do not show significant discrepancy in the optimum design results, but the former appears more realistic and time saving than the latter for this specific study.

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Design Optimization and Reliability Analysis of Jacket Support Structure for 5-MW Offshore Wind Turbine (해상풍력발전기 자켓 지지구조물의 최적설계 및 신뢰성해석)

  • Lee, Ji-Hyun;Kim, Soo-Young;Kim, Myung-Hyun;Shin, Sung-Chul;Lee, Yeon-Seung
    • Journal of Ocean Engineering and Technology
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    • v.28 no.3
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    • pp.218-226
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    • 2014
  • Since the support structure of an offshore wind turbine has to withstand severe environmental loads such as wind, wave, and seismic loads during its entire service life, the need for a robust and reliable design increases, along with the need for a cost effective design. In addition, a robust and reliable support structure contributes to the high availability of a wind turbine and low maintenance costs. From this point of view, this paper presents a design process that includes design optimization and reliability analysis. First, the jacket structure of the NREL 5-MW offshore wind turbine is optimized to minimize the weight and stresses, while satisfying the design requirements. Second, the reliability of the optimum design is evaluated and compared with that of the initial design. Although the present study results in a new optimum shape for a jacket support structure with reduced weight and increased reliability, the authors suggest that the optimum design has to be accompanied by a reliability analysis during the design process, as well as reliability based design optimization if needed.

Optimum Design Criteria of Steel Structure members based on ETCM (ETCM에 의한 강구조부재의 최적설계규준)

  • 이증빈;박주원
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1996.10a
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    • pp.277-287
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    • 1996
  • Based on the developments of the reliability-based steel structural analysis and design as well as the extending knowledgy on the probabilitic characteristics of loading and resistance the probability based design criteria have been successful Iy developed for many students. The existing design codes, which are genarally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of loads and resistance and the basic reliability concepts. It is recognized to develope the design criteria by ETCM(Expected Total cost Minimization). In this study, therefore, the proper probability based design criteria (Optimum load and resistance factor design formats ) has been developed based on the safety levels observed from calibration Iii th existing standards, which applies to the ultimate limit states of steel structural members.

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Reliability-Based Design Optimization using Semi-Numerical Strategies for Structural Engineering Applications

  • Kharmanda, G.;Sharabatey, S.;Ibrahim, H.;Makhloufi, A.;Elhami, A.
    • International Journal of CAD/CAM
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    • v.9 no.1
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    • pp.1-16
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    • 2010
  • When Deterministic Design Optimization (DDO) methods are used, deterministic optimum designs are frequently pushed to the design constraint boundary, leaving little or no room for tolerances (or uncertainties) in design, manufacture, and operating processes. In the Reliability-Based Design Optimization (RBDO) model for robust system design, the mean values of uncertain system variables are usually used as design variables, and the cost is optimized subject to prescribed probabilistic constraints as defined by a nonlinear mathematical programming problem. Therefore, a RBDO solution that reduces the structural weight in uncritical regions does not only provide an improved design but also a higher level of confidence in the design. In this work, we seek to improve the quality of RBDO processes using efficient optimization techniques with object of improving the resulting objective function and satisfying the required constraints. Our recent RBDO developments show its efficiency and applicability in this context. So we present some recent structural engineering applications demonstrate the efficiency of these developed RBDO methods.