• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.91-94
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• 1990

The object of this study is to develop computer programs with which ordinary engineers can analyse or design steel-concrete composite teams using optimization technique. Various design ana construction techniques which could maximize load carrying capacities and control concrete tension cracks effectively are studied and included in the programs. Analysis results show that proposed construction techniques can reduce steel weight by about 10%∼20% compared with ordinary composite beam. Concrete tensile stresses can also be controlled affectively by the suggested techniques.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.439-448
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• 2000

A multi-level design synthesis (MLDA) algorithm for efficiently optimizing orthotropic steel deck bridges is proposed in the paper, because it is usually very difficult to optimize orthotropic steel deck bridges using a conventional single-level (CSL) algorithn since the bridges have a large number of members and show complex structural behaviors. In the proposed MLDS algorithms a coordination method is introduced to divide the bridges into main girders and orthotropic steel decks and decomposition method is also used to reduce the number of design variables of the decks for system level optimization. For efficient optimization of the bridges the MLDS algorithm incorporates the crucial approximation techliques such as constraints deletion and stress reanalysis. The constraint deletion technique for deflection is found to be very useful for the optimization problem of the bridges, since a deflection constraint is usually inactive in the design. Considering the complex system of the bridges, the proposed the efficient stress reanalysis technique may prove to be a very effective method, since it does not require expensive design sensitivity analyses. The applicability and robustness of the MLDS algorithm is demonstrated using various numerical examples and compared with other algorithm presently available so far.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.505-513
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• 2001

In this study, an optimum design algorithm using efficient reanalysis is proposed for seismic design of Reinforced Concrete (RC) piers. The proposed algorithm for optimization of RC piers is based on efficient reanalysis technique. Considering structural behavior of RC piers, the other approximation technique such as artificial constraint deletion is introduced to increase the efficiency of optimization. The efficiency and robustness of the proposed algorithm including the proposed reanalysis technique is demonstrated by comparing it with a conventional optimization algorithm. A few of design examples are optimized to show the applicability of the proposed algorithm.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.31-36
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• 2011

In this paper, an analytical model of a cantilever beam having a midpoint load is considered for structural optimization and design. This involves creation of the geometry through a parametric study of all design variables. For this purpose, the optimization of the cantilever beam was elaborated in order to find the optimum geometry which minimizes its volume eventually for minimum weight by FEM (finite element method) analysis. Such geometry can be obtained by different combinations of width and height, so that the beam may have the same cross-sectional area, yet different dynamic behavior. So for optimum safe design, besides minimum volume it should have minimum vibration as well. In order to predict vibration, different dynamic analyses were performed simultaneously to identify the resonant frequencies and mode shapes belonging to the lowest three modes of vibration. Next, by introducing damping effects, the tip displacement and bending stress at the fixed end was evaluated under dynamic loads of varying frequency. Investigation of the results clearly shows that only structural analysis is not enough to predict the optimum values of dimension for safe design it must be aided by dynamic analysis as well.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.138-143
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• 2007

The leading-cab (high energy absorption area) of rolling stock directly is impacted on the frontal crash unlike other cabs. Thus, leading-cab has a structurally complex shape to solve getting concentrated loads. However, in order to enhance structural performance and to achieve the weight reduction of cab, changing the sizes and adjusting the distance of members do not take an effective result. Therefore, in design phase, to find the material arrangement which helps structural capacity be better should be done. This research applies the topology optimization to concept design of protective shell frame on strategy of crush energy absorption with considering pressure and vertical loads acting on the principal part of leading-cab. In this research, topology optimization method focuses on structural design, and which yields optimal material arrangement under given loads and boundary conditions using density method which has the density of material as design variables. Finally, this research presents optimal material arrangement and structure of protective shell frame on given loads with applying topology optimization.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.161-168
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• 2021

As the demand for high speed and high precision increases in the field of machine tool, interest in stiffness and vibration of machine tool is increasing. However, it takes a lot of time to develop a detailed design of machine tool based on experience, and it is difficult to design appropriately. Recently, structural optimization using FEM are increasingly used in machine tool design. But, it is difficult to optimize in consideration of the vibration state of the structure since optimization through stress distribution of a structure is mainly used, In this paper, Static structural analysis, mode analysis, and harmonic analysis using FEM were conducted to optimize the head structure that has the most influence on machining in a 5-axis machine tool. It is proposed a topology optimization analysis method that considers both static stiffness and dynamic stiffness using objective function design.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.667-694
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• 2015

The suspended dome system is a new structural form that has become popular in the construction of long-span roof structures. Suspended dome is a kind of new pre-stressed space grid structure that has complex mechanical characteristics. In this paper, an optimum topology design algorithm is performed using the enhanced colliding bodies optimization (ECBO) method. The length of the strut, the cable initial strain, the cross-sectional area of the cables and the cross-sectional size of steel elements are adopted as design variables and the minimum volume of each dome is taken as the objective function. The topology optimization on lamella dome is performed by considering the type of the joint connections to determine the optimum number of rings, the optimum number of joints in each ring, the optimum height of crown and tubular sections of these domes. A simple procedure is provided to determine the configuration of the dome. This procedure includes calculating the joint coordinates and steel elements and cables constructions. The design constraints are implemented according to the provision of LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Constitution). This paper explores the efficiency of lamella dome with pin-joint and rigid-joint connections and compares them to investigate the performance of these domes under wind (according to the ASCE 7-05), dead and snow loading conditions. Then, a suspended dome with pin-joint single-layer reticulated shell and a suspended dome with rigid-joint single-layer reticulated shell are discussed. Optimization is performed via ECBO algorithm to demonstrate the effectiveness and robustness of the ECBO in creating optimal design for suspended domes.

• Structural Engineering and Mechanics
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• v.51 no.5
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• pp.707-725
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• 2014

In order to improve the crane-hook's performance and service life, we formulate a multi-criteria shape design problem considering practical conditions. The structural weight, the displacement at specified points and the induced matrix norm of stiffness matrix are adopted as the evaluation items to be minimized. The heights and widths of cross-section are chosen as the design variables. The design variables are expressed in terms of shape functions based on the Gaussian function. For this multi-objective optimization problem with three items, we utilize a multi-objective evolutionary algorithm, that is, the multi-objective Particle Swarm Optimization (MOPSO). As a common feature of obtained solutions, the side views are tapered shapes similar to those of actual crane-hook designs. The evaluation item values of the obtained designs demonstrate importance of the present optimization as well as the feasibility of the proposed optimal design approach.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.102-109
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• 2009

This study proposes the structural optimization of a manifold valve. FE analysis is performed to evaluate the strength of a manifold valve. In addition, the structural optimization technique is applied to reduce its weight. In this study, the optimization method using the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint. The maximum stress and the weight are replaced by the metamodels. In this process, tile sample points are generated by latin-hypercube design. Optimum designs are obtained by ANSYS Workbench and the in-house program.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1005-1010
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• 2004

The structural optimization has been carried out in the continuous design space or in the discrete design space. Generally, available designs are discrete in design practice. But methods for discrete variables are extremely expensive in computational cost. In order to overcome this weakness, an iterative optimization algorithm was proposed for design in the discrete space, which is called as a sequential algorithm using orthogonal arrays (SOA). We focus to verify the fact that the local solution can be obtained throughout the optimization with this algorithm. The local solution is defined in discrete design space. Then the search space, which is the set of candidate values of each design variables formed by the neighborhood of current design point, is defined. It is verified that a local solution can be founded by moving sequentially the search space. The SOA algorithm has been applied to problems such as truss type structures. Then it is confirmed that a local solution can be obtained using the SOA algorithm