• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.511-516
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• 2004

The objective of this study is to optimally design FRP-concrete members of a bridge structure. Using the GENESIS7.0 that is a commercial optimization program we performed an optimal design with design parameters that consist of height, width of FRP member, height of concrete. And we practiced an optimal design with the design variables, thickness of upper flange, bottom flange, and web. The results of these studies are summarized as follows : (1) Thickness of composite-concrete is proper at over loon (2) FRP member reaches the optimal section when the width of the FRP member is 20cm its height is 10cm and the height of the composite-concrete is 12cm.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.301-308
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• 1999

This paper describes the application of genetic algorithm(GA) in the discrete optimal design of truss structures. Stochastic processes generate an intial population of design and then apply principles of natural selection/survival of the fittest to improve the design. GA is applied to minimum weight of truss subject to stress and displacement constraints under multiple loading conditions. First, optimum solutions obtained from GA are compared to verify the reliability of GA with m well-known transmission tower structure which is referred to by other authors. Then, discrete optimal design is performed in satisfying service conditions of truss structure with commercially available fabricated sizes. From the results, it is found that GA search technique is very effective for discrete optimal design of truss structure and has high robustness.

• Steel and Composite Structures
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• 제44권5호
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• pp.603-617
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• 2022

Structural design, in general, is developed through trial and error technique which is guided by standards criteria and based on the intuition and experience of the engineer, a context that leads to structural over-dimensioning, with uneconomic solutions. Aiming to find the optimal design, structural optimization methods have been developed to find a balance between cost, structural safety, and material performance. These methods have become a great opportunity in the steel structural engineering domain since they have as their main purpose is weight minimization, a factor directly correlated to the real cost of the structure. Assuming an objective function of minimum weight with stress and displacement constraints provided by Brazilian standards, the present research proposes the sizing optimization and combined approach of sizing and shape optimization, through a software developed to implement the Simulated Annealing metaheuristic algorithm. Therefore, two steel plane frame layouts, each admitting four typical truss geometries, were proposed in order to expose the difference between the optimal solutions. The assessment of the optimal solutions indicates a notable weight reduction, especially in sizing and shape optimization combination, in which the quantity of design variables is increased along with the search space, improving the efficiency of the optimal solutions achieved.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.249-260
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• 2023

The uncertainties involved in structural performances are of importance when the optimum number and property of seismic retrofit devices are determined. This paper proposes a seismic retrofit design framework for asymmetric soft-first-story buildings, considering uncertainties in the soil condition and seismic retrofit device. The effect of the uncertain parameters on the structural performance is used to find a robust and optimal seismic retrofit solution. The framework finds a robust and optimal seismic retrofit solution by finding the optimal locations and mechanical properties of the seismic retrofit device for different realizations of the uncertain parameters. The structural performance for each realization is computed to evaluate the effect of the uncertainty parameters on the seismic performance. The framework utilizes parallel processing to decrease the computationally intensive nonlinear dynamic analysis time. The framework returns a robust design solution that satisfies the given limit state for every realization of the uncertain parameters. The proposed framework is applied to the seismic retrofit design of a five-story asymmetric soft-first-story case study structure retrofitted with a viscoelastic damper. Robust optimal parameters for retrofitting a structure to satisfy the limit state for the different realizations of the uncertain parameter are found using the proposed framework. According to the performance evaluation results of the retrofitted structure, the developed framework is proved effective in the seismic retrofit of the asymmetric structure with inherent uncertainties.

• 한국지진공학회논문집
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• 제7권5호
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• pp.93-102
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• 2003

이 연구에서는 지진하중을 받는 빌딩구조물에 대한 복합구조제어시스템의 최적설계방법을 제시한다. 복합구조제어시스템의 설계는 구조물의 부재뿐만 아니라 수동제어시스템 및 능동제어시스템의 용량 및 위치 최적화 과정으로 정의된다. 최적설계는 이 연구에서 제안된 다단계 목표계획법(Multi-Stage Goal Programming)을 이용하여 최적화문제를 정식화하고 목표갱신 유전자알고리즘(Goal-Updating Genetic Algorithm을 적용하여 합리적인 최적화를 진행해가는 과정으로 구성된다. 다단계 목표계획법에서는 구조물의 층간 상대변위와 제어시스템의 용량에 대한 설계목표를 여러 단계로 선정하고, 각 물리량과 설계목표간의 정규화된 거리 합으로서 목적함수를 정의한다. 목표갱신 유전자알고리즘은 각 단계별 설계목표를 만족하는 최적해를 검색하고, 현 단계의 모든 설계목표를 만족하는 최적해가 존재할 경우 설계목표를 순차적으로 갱신함으로써 보다 상위수준의 설계목표로 접근해 나아간다. 지진하중을 받는 9층의 빌딩구조물에 대한 수치 예를 통하여 복합구조제어시스템의 통합최적설계 과정을 기술하였고, 구조부재, 수동 및 능동제어시스템이 균등분포된 구조물과 최적 설계결과를 비교하여 제시하는 방법의 효율성을 검증하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.163-170
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• 2004

The main objective of this research is to determine the optimal sections of infrastructure (the pier and foundation) for orthotropic steel decks which is a part of prefabricated passenger car overpasses. Since the bridge to be designed allows only passenger cars, design loads are determined according to this condition. The total volume of the infrastructure is formulated as the objective function and the design constraints are based on the 'Korean Bridge Design Code' and 'Design Manual of Steel Framed Pier'. The programs used in this research are MATLAB 6.5 and MIDAS CIVIL.

• 한국공간구조학회논문집
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• 제19권2호
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• pp.43-50
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• 2019

A smart connective control system was invented recently for coupling control of adjacent buildings. Previous studies on this topic focused on development of control algorithm for the smart connective control system and design method of control device. Usually, a smart control devices are applied to building structures after structural design. However, because structural characteristics of building structure with control devices changes, a iterative design is required for optimal design. To defeat this problem, an integrated optimal design method for a smart connective control system and connected buildings was proposed. For this purpose, an artificial seismic load was generated for control performance evaluation of the smart coupling control system. 20-story and 12-story adjacent buildings were used as example structures and an MR (magnetorheological) damper was used as a smart control device to connect adjacent two buildings. NSGA-II was used for multi-objective integrated optimization of structure-smart control device. Numerical simulation results show the integrated optimal design method proposed in this study can provide various optimal designs for smart connective control system and connected buildings presenting good control performance.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.475-482
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• 2002

This paper provides the systematic procedure to determine the weighting matrices of optimal controllers considering structural energy. Optimal controllers consist of LQR and ILQR. The weighting matrices are needed first in the conventional optimal control design strategy. However, they are in general dependent on the experienced knowledge of controll designers. Applying the Lyapunov function to the total structural energy and using the contrition that its derivative is negative, we can determine the weighting matrices without difficulty. It is proven that the control efficiency is achieved well for LQR and ILQR.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.812-818
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• 2001

This paper proposes an optimum design method of structural and control systems, taking a 2-D truss structure as an example. The structure is supposed to be subjected to initial static loads and disturbances. For the structure, a FEM model is formed, and using modal transformation, the equation of motion is transformed into that of modal coordinates in order to reduce the D.O.F. of the FEM model. The structure is controlled by an output feedback $H^$\infty$$ controller to suppress the effect of the disturbances. The design variables of the simultaneous optimal design of control-structure systems are the cross sectional areas of truss members. The structural objective function is the structural weight. The control objective function is the $H^$\infty$$ norm, that is, the performance index of control. The second structural objective function is the energy of the response related to the initial state, which is derived from the time integration of the quadratic form of the state in the closed-loop system. In a numerical example, simulations have been carried out. Through the consideration of structural weight and $H^$\infty$$ norm, an advantage of the simultaneous optimum design of structural and control systems is shown. Moreover, while the optimized performance index of control is almost kept, we can acquire better design of structural strength.

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1279-1288
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• 2023

Recently, domestic leisure boats have been actively researching eco-friendly product development to enter the global market. Since the hulls of existing leisure boats are mainly made of fiber reinforced plastic (FRP) or aluminum, design techniques for securing structural safety by applying related materials have been mainly studied. In this study, an initial structural design safety assessment of a trimaran pontoon leisure boat with a modular hull structure and eco-friendly high-density polyethylene (HDPE) material was conducted, and sensitivity evaluation and optimization analysis for lightweight design were performed. The initial structural design safety assessment was carried out by creating a finite element analysis model and applying the loading conditions specified in the ship classification regulation to check whether the specified allowable stresses are satisfied. For the sensitivity evaluation, the influence of stress and weight of each hull structural member was evaluated using the orthogonal array design of experiments method, and an approximate model based on the response surface method was generated using the results of the design of experiments. The optimization analysis set the thickness of the hull structural members as the design variable and considered the optimal design formulation to minimize the weight while satisfying the allowable stress. The algorithm of the optimization analysis applied the Gradient-population Based Optimizer (GBO) to improve the accuracy of the optimal solution convergence while reducing the numerical cost. Through this study, the optimal design of a newly developed eco-friendly trimaran pontoon leisure boat with a weight reduction of 10% was presented.