• Computers and Concrete
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• 제18권5호
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• pp.983-998
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• 2016

Structural optimization is one of the most important topics in structural engineering and has a wide range of applicability. Therefore, the main objective of the present study is to apply the Lagrange Multiplier Method (LMM) for minimum cost design of singly and doubly reinforced rectangular concrete beams. Concrete and steel material costs are used as objective cost function to be minimized in this study, and ultimate flexural strength of the beam is considered to be as the main constraint. The ultimate limit state method with partial material strength factors and equivalent concrete stress block is used to derive general relations for flexural strength of RC beam and empirical coefficients are taken from topic 9 of the Iranian National Building Regulation (INBR9). Optimum designs are obtained by using the LMM and are presented in closed form solutions. Graphical representation of solutions are presented and it is shown that proposed design curves can be used for minimum cost design of the beams without prior knowledge of optimization and without the need for iterative trials. The applicability of the proposed relations and curves are demonstrated through two real life examples of SRB and DRB design situations and it is shown that the minimum cost design is actually reached using proposed method.

• 한국재난관리표준학회지
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• 제4권1호
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• pp.49-55
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• 2011

본 연구는 철근 콘크리트 구조물의 새로운 자동화 최적설계 알고리즘을 제시하였다. 기존의 주철근과 콘크리트 단면사이즈 등의 국한된 최적설계 범위를 벗어나 철근의 부착길이, 매입길이, 콘크리트 커버두께 등 세부설계사항까지 모두 고려한 실무에 적합한 효용성 높은 설계알고리즘을 제시함으로써 앞으로 실무분야에 많은 기여를 할 수 있다고 보여 진다.

• 한국구조물진단유지관리공학회 논문집
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• 제10권3호
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• pp.175-185
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• 2006

본 연구는 FSM 공법의 PSC 박스 거더교를 최소경비로 자동 설계하는 최적설계 프로그램을 이용하여 다양한 변단면 거더유형을 가진 등경간 및 부등경간 거더교에 대하여 최적설계를 수행하였다. 또한 각 변단면 거더유형에서 산출된 최적의 긴장재 배치에 관하여 연구함으로서 향후 복잡한 구조물에 대하여 더욱 적절한 긴장재의 배치형태에 대한 방향을 제시하고자 하는데 목적이 있다. 사용된 최적설계 프로그램은 축차 무제약 최소화 기법을 이용하였고, 설계과정에서 설계점들이 설계가능 영역밖에 있는 것을 허용할 수 있도록 Kavlie가 제안한 확장 벌칙함수를 도입하였다. 또한 설계점들의 탐사 방법은 Powell's direct search method를 사용하며, 설계시간을 단축시키기 위해 설계점 변화에 따른 단면력 변화를 Gradient를 이용하여 근사화 시키는 방법을 사용하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.309-316
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• 1999

Laminated composite plates are very useful in various fields of engineering where high strength-to-weight and stiffness-to-weight ratios are required. Design optimization of composite structures has gained importance in recent years as the engineering applications of fiber reinforced materials have increased and weight savings has become an essential design objective. However, due to the anisotropic material properties of laminated composite structure it is very difficult to analyze and design. In this study, numerical optimization technique together with the finite element method is used to find the optimum design of FRP. Various combination of fiber orientation for the laminate layers are investigated and several local optimum solutions are found.

• Structural Engineering and Mechanics
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• 제64권5호
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• pp.579-589
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• 2017

This paper deals with the optimum cost design of partially prestressed concrete I crosssectioned beams by using Genetic Algorithms. For this purpose, the optimum cost design of two selected example problems that have different characteristics in behavior are performed via Genetic Algorithms by determining their objective functions, design variables and constraints. The results obtained from the technical literature are compared with the ones obtained from this study. The interpretation of the results show that the design of partially prestressed concrete I crossectioned beams from cost point of view by using Genetic Algorithms is 35~50 % more economical than the traditional ones (technical literature) without conceding safety.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.271-278
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• 2002

Structural optimization using improved higer-order convex approximation is proposed in this paper. The proposed method is a generalization of the convex approximation method. The order of the approximation function for each constraint is automatically adjusted in the optimization process. And also the order of each design variable is differently adjusted. This self-adjusted capability makes the approximate constraint values conservative enough to maintain the optimum design point of the approximate problem in feasible region. The efficiency of proposed algorithm, compared with conventional algorithm is successfully demonstrated in the Three-bar Truss example.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.401-407
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• 2004

This study proposes a interim development result for the l-㎾ class small wind turbine system, which is applicable to relatively low wind speed regions like Korea and has the variable pitch control mechanism. In the aerodynamic design of the wind turbine blade, parametric studies were carried out to determine an optimum aerodynamic configuration which is not only more efficient at low wind speed but whose diameter is not much larger than similar class other blades. A light composite structure, which can endure effectively various loads, was newly designed. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Moreover both structural safety and stability were verified through the full-scale structural test.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.290-303
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• 2017

This paper aims to build a drone platform based on an optimum design of its single arm. We assumed its single arm as a cantilevered beam with a tip mass. Based on the numerical optimization theory, we conducted validation and optimization of a new design by comparing the results with the similar ones obtained by ANSYS. Finally, this design is reflected in the control simulation, and the requirement of an optimum structural design considering the resonance situation is demonstrated.

• 대한조선학회 특별논문집
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• 대한조선학회 2011년도 특별논문집
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• pp.117-126
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• 2011

The buckling assessment of plate panels described in common structural rules (CSR) is to be determined according to the buckling utilization factor with hull girder stresses calculated on net hull girder sectional properties. As the thickness requirement for the buckling assessment of plate panels is not explicitly given in CSR, a lot of time is spent to find the proper thickness of plate panels until reaching to an allowable buckling utilization factor. In this study, in order to reduce time and cost, the thickness requirement of plate panels satisfying buckling assessment was derived. The structural design system included with the thickness requirement for buckling assessment was developed. The system is called as Oil-tanker Automated Structural Investigation System (OASIS). The design result of longitudinal strength members using OASIS was verified by Nauticus Hull which is the rule scantling software of DNV. Finally, optimum design of a double hull tanker for the minimum weight using OASIS was presented.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.205-210
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• 2000

An optimum design algorithm of PSC box girder bridges using design sensitivity analysis is proposed in this paper. For the efficiency of the proposed algorithm, approximated reanalysis techniques using design sensitivity analysis are introduced. And also to save the numerical efforts, an efficient reanalysis technique through approximated structural responses is proposed. A design sensitivity analysis of structural response is executed by automatic differentiation(AD). The efficiency and robustness of the proposed algorithm, compared with conventional algorithm, is successfully demonstrated in the numerical example.