• Structural Engineering and Mechanics
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• 제81권3호
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• pp.367-378
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• 2022

In this study, combined size and shape optimization of spatial truss tower structures are presented by using new optimization algorithms named Rao-1, and Rao-2. The nodal displacements, allowable stress and buckling for compressive members are taken into account as structural constraints for truss towers. The discrete and continuous design variables are used as design variables for size and shape optimization. To show the efficiency of the proposed optimization algorithm, 25-bar, and 39-bar 3D truss towers are solved for combined size and shape optimization. The 72-bar, and 160-bar 3D truss towers are solved only by size optimization. The optimal results obtained from this study are compared to those given in the literature to illustrate the efficiency and robustness of the proposed algorithm. The structural analysis and the optimization process are coded in MATLAB programming.

• 한국강구조학회 논문집
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• 제23권4호
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• pp.465-474
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• 2011

본 연구는 마이크로 유전 알고리즘을 이용하여 트러스 구조물의 단면적 및 형상을 최적화 하였다. 구조물의 최소 물량을 얻기 위하여 허용 응력 및 좌굴 응력과 같은 여러 제약조건이 고려되었으며, 이를 통해 트러스 구조물의 최적 설계 시 최적화된 부재의 단면적과 구조물의 좌표를 얻었다. 트러스 구조물의 최적 설계에 적용가능 한 제안된 기법을 이용하여 다양한 예제들을 선정하여 최적화를 수행하였으며, 기존 연구 결과와 비교를 통해 본 마이크로 유전 알고리즘의 효과를 입증하였다.

• Structural Engineering and Mechanics
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• 제44권3호
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• pp.379-403
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• 2012

In recent years, the need for optimal design of structures under time-history loading aroused great attention in researchers. The main problem in this field is the extremely high computational demand of time-history analyses, which may convert the solution algorithm to an illogical one. In this paper, a new framework is developed to solve the size optimization problem of steel truss structures subjected to ground motions. In order to solve this problem, the covariance matrix adaptation evolution strategy algorithm is employed for the optimization procedure, while a generalized regression neural network is utilized as a meta-model for fitness approximation. Moreover, the computational cost of time-history analysis is decreased through a wavelet analysis. Capability and efficiency of the proposed framework is investigated via two design examples, comprising of a tower truss and a footbridge truss.

• 한국전산구조공학회논문집
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• 제25권1호
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• pp.73-80
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• 2012

대공간 구조물은 형태에 따라 구조물의 설계와 시공에 미치는 영향이 크기 때문에 초기 단계에서의 최적형태 설계가 중요하다. 그러나 기존의 대공간 구조물의 최적형태 설계는 구조엔지니어의 직관이나 경험을 바탕으로 수행되어 왔다. 따라서 본 연구에서는 대공간 트러스 구조물의 체계적인 최적형태 설계를 위해 위상최적화 기법과 Cellular Automata 모델을 이용한 통합프로세서를 제안하고자 한다. 먼저 위상최적화 기법을 이용하여 구조물의 초기 최적형상을 찾고, 다음 단계로 Cellular Automata 규칙에 의해 생성된 구조패턴을 적용하여 대공간 트러스 구조형태를 생성한다. 최종적으로 구조해석을 실시하고 크기최적화를 적용함으로써 설계조건을 만족하는 최적형태를 제안하고자 한다.

• Structural Engineering and Mechanics
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• 제60권6호
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• pp.1093-1117
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• 2016

Global sensitivity analysis (GSA) has been widely used to investigate the sensitivity of the model output with respect to its input parameters. In this paper a new single-solution search optimization algorithm is developed based on the GSA, and applied to the size optimization of truss structures. In this method the search space of the optimization is determined using the sensitivity indicator of variables. Unlike the common meta-heuristic algorithms, where all the variables are simultaneously changed in the optimization process, in this approach the sensitive variables of solution are iteratively changed more rapidly than the less sensitive ones in the search space. Comparisons of the present results with those of some previous population-based meta-heuristic algorithms demonstrate its capability, especially for decreasing the number of fitness functions evaluations, in solving the presented benchmark problems.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.39-66
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• 2014

This study deals with the design of bridge girder structures and consists of two parts. In the first part an optimal bridge girder topology is determined using a software based on structure compliance minimization with constraints imposed on the body mass, developed by the authors. In the second part, an original way in which the topology is mapped into a bridge girder structure is shown. Additionally, a method of converting the thickness of the bars obtained using the topology optimization procedure into cross sections is introduced. Moreover, stresses and material consumption for a girder design obtained through topology optimization and a typical truss girder are compared. Concluding, this paper shows that topology optimization is a good tool for obtaining optimal bridge girder designs.

• 대한토목학회논문집
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• 제12권3호
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• pp.39-55
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• 1992

본(本) 연구(硏究)에서는 트러스구조물(構造物)의 효율적(效率的)인 형상최적화(形狀最適化)를 위해서 3단계분할최적화(段階分割最適化) 기법(技法)을 유도(誘導)하였다. 3단계분할최적화(段階分割最適化) 기법(技法)을 적용(適用)하기 위하여 제(第)1단계(段階)에서 설계변수(設計變數)로 목적함수(目的函數)는 구조물(構造物)이 에너지를 최대(最大)로 흡수(吸收)할 수 있도록 변형(變形)에너지를 택하였으며 제약조건식(制約條件式)으로는 허용응력(許容應力), 좌굴응력(挫屈應力), 변위제약(變位制約) 및 다(多) 재하조건(載荷條件)을 고려(考慮)하여 최적화문제(最適化問題)를 형성(形成)하였다. 제(第) 2단계(段階)에서 설계변수(設計變數)는 부재단면적(部材斷面積)으로하여 목적함수(目的函數)는 구조물(構造物)의 중량(重量)이 최소(最小)가 되도록 중량함수(重量函數)를 택하였으며 제약조건식(制約條件式)으로는 제(第)1단계(段階)에서 얻은 최대변위(最大變位)를 대입(代入)한 평형조건식(平衡條件式) 및 다재하조건(多載荷條件)을 고려(考慮)하여 최적화문제(最適化問題)를 형성(形成)하였다. 제(第) 3단계(段階)에서는 조정변수(調整變數)를 절점좌표(節點座標)로 하고 목적함수(目的函數)로는 중량함수(重量函數)로 하여 최적화(最適化) 문제(問題)를 형성(形成)하였다. 이와같이 형성(形成)된 제(第)1, 제(第)2단계(段階)의 최적화(最適化) 문제(問題)는 선형계획문제(線形計劃問題)로 된다. 따라서 3단계(段階) 분할최적화(分割最適化) 기법(技法)은 최적화(最適化) 과정(過程)이 간편(簡便)하고 구조해석(構造解析) 및 감도분석(感度分析)을 위한 기법(技法)을 적용(適用)할 필요(必要)가 없으므로 최적화(最適化) 과정중(過程中) 구조해석(構造解析) 및 감도분석(感度分析)에 요구(要求)되는 시간(時間)을 줄일 수 있는 효율적(效率的)인 기법(技法)이었다. 제(第) 3단계(段階)에서는 절점좌표(節點座標)를 설계변수(設計變數)로 하므로서 무제약최적화문제(無制約最適化問題)로 형성(形成)되므로 최적화과정(最適化過程)이 용이(容易)하다. 또한 본(本) 연구(硏究)는 각(各) 단계(段階)에 각각(各各) 다른 최적화기준(最適化基準)을 사용함으로써 수염속도(收斂速度)를 향상(向上)시키고 있다. 본(本) 연구(硏究)의 기법(技法)을 4종(種)으 트러스 구조물(構造物)에 적용(適用)한 결과 트러스 구조물(構造物)의 형태(形態), 제약조건식(制約條件式)에 구애받지 않고 효율적(效率的)으로 최적해(最適解)에 수염(收斂)함과 동시(同時)에 타(他)의 연구(硏究)와 거의 동일(同一)한 연구결과(硏究結果)를 얻었다.

• Structural Engineering and Mechanics
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• 제52권3호
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• pp.445-468
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• 2014

In this paper a new particle swarm ray optimization algorithm is proposed for truss shape and size optimization with natural frequency constraints. These problems are believed to represent nonlinear and non-convex search spaces with several local optima and therefore are suitable for examining the capabilities of new algorithms. The proposed algorithm can be viewed as a hybridization of Particle Swarm Optimization (PSO) and the recently proposed Ray Optimization (RO) algorithms. In fact the exploration capabilities of the PSO are tried to be promoted using some concepts of the RO. Five numerical examples are examined in order to inspect the viability of the proposed algorithm. The results are compared with those of the PSO and some other existing algorithms. It is shown that the proposed algorithm obtains lighter structures in comparison to other methods most of the time. As will be discussed, the algorithm's performance can be attributed to its appropriate exploration/exploitation balance.

• 한국공간구조학회논문집
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• 제24권3호
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• pp.35-42
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• 2024

Recent advances in computer technology have made it possible to solve numerous challenges but require faster hardware development. However, the size of the classical computer has reached its physical limit, and researchers' interest in quantum computers is growing, and it is being used in various engineering fields. However, research using quantum computing in structural engineering is very insufficient. Therefore, in this paper, the characteristics of qubits, the minimum unit of quantum information processing, were grafted with the crow search algorithm to propose QCSA (quantum crow search algorithm) and compare the convergence performance according to parameter changes. In addition, by performing the optimal design of the example truss structure, it was confirmed that quantum computing can be used in the architectural field.

• 한국정밀공학회지
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• 제14권3호
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• pp.89-97
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• 1997

A genetic algorithm (GA) is a stochastic direct search strategy that mimics the process of genetic evolution. The GA applied herein works on a population of structural designs at any one time, and uses a structured information exchange based on the principles of natural selection and wurvival of the fittest to recombine the most desirable features of the designs over a sequence of generations until the process converges to a "maximum fitness" design. Principles of genetics are adapted into a search procedure for structural optimization. The methods consist of three genetics operations mainly named selection, cross- over and mutation. In this study, a method of finding the optimum topology of truss/beam structure is pro- posed by using the GA. In order to use GA in the optimum topology problem, chromosomes to FEM elements are assigned, and a penalty function is used to include constraints into fitness function. The results show that the GA has the potential to be an effective tool for the optimal design of structures accounting for sizing, geometrical and topological variables.variables.