• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.145-152
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• 2003

An optimal design method in cooperated with nonlinear inelastic analysis method is presented. The proposed nonlinear inelastic method overcomes the difficulties due to incompatibility between the elastic global analysis and the limit state member design in the conventional LRFD method. The genetic algorithm uses a procedure based on Darwinian notions of survival of the fittest, where selection, crossover, and mutation operators are used among sections in the database to look for high performance ones. They satisfy the constraint functions and give the lightest weight to the structure. The objective function is set to the total weight of the steel structure and the constraint functions are load-carrying capacities, serviceability, and ductility requirement. Case studies of a three-dimensional frame and a three-dimensional steel arch bridge are presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.277-284
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• 2003

One of important problem, in large space structure, is to overcome the self-weight of roof structure. This problem can be solved with using tension members effectively. Thus the rapid progress of hybrid structure, that makes effective use of the means of settling, has a good effect on realizing the large space. These systems of hybrid structure have the advantages of light weight and its own internal redundancy, but are occurred unstable phenomenon such as bifurcation or snap-through buckling, when the load level is come to the critical point. Among the hybrid structure, cable dome is shown the strong nonlinearity of unstable phenomenon in accordance with the external force. Therefore, the purpose of this study is to analyze and verify comparatively the unstable phenomenon of the Geiger and Flower type cable dome structures under axismmetric load.

• Structural Engineering and Mechanics
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• v.14 no.2
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• pp.223-236
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• 2002

The main objective of the present paper is to address a formal procedure for orthotropic steel plates design. The theme of the proposed approach is to recast the design procedure into a mathematical programming model. The objective function to be optimized is the total weight of the structure. The total weight is function of its layout parameters and structural element design variables. Mean while the proposed approach takes into consideration the strength and rigidity criteria in addition to other dimensional constraints. A nonlinear programming model is developed which consists of a nonlinear objective function and a set of implicit/explicit nonlinear constraints. A transformation method is adopted for minimization strategy, where the primal model constrained problem is transformed into a sequence of unconstrained minimization models. The search strategy is based on the well-known Fletcher/Powell algorithm. The finite element technique is adopted for discretization and analysis strategies. Mindlin theory is selected to simulate the finite element model and a selective reduced integration scheme is exploited to avoid a shear lock problem.

• Structural Engineering and Mechanics
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• v.35 no.5
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• pp.539-554
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• 2010

Light weight superstructure is beneficial for bridges in remote areas and in emergency erection. In such weight sensitive applications, combination of fibre reinforced plastics (FRP) as material and box-girders as a structural system have great scope. This combination offers various options to tailor structure and its elements but this flexibility poses greater challenge in optimum design. In this paper a procedure is derived for a generalised optimum design of FRP box-girder bridges, using genetic algorithms (GA). The formulation of the optimum design problem in the form of objective function and constraints is presented. Size, configuration and topology optimization are done simultaneously. A few optimum design studies are carried out to check the performance of the developed procedure and to get trends in the optimum design which will be helpful to the new designers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.149-156
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• 1999

Numerical studies were carried out to investigate the mechanical properties of competent hysteric isolators for seismic design of bridge. For dynamic analysis, bridges with isolator were simplified to a model with single degree of freedom. The initial stiffness and the yielding forces of hysteric isolators were varied. Seismic responses obtained by time history analysis show that about 4% of the weight acting as the inertia force is appropriate for the yielding force of isolator. And also better results could be achieved with the values about two times the weight per unit displacement for the initial stiffness of isolator.

• Structural Engineering and Mechanics
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• v.27 no.3
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• pp.347-363
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• 2007

Assessment of structural behaviour of corrosion affected structures is an important issue, which would help in making certain decisions pertaining to the inspection, repair, strengthening, replacement and demolition of such structures. The paper presents formulations to predict the loss of weight and the loss of cross-sectional area of the reinforcing bar undergoing corrosion based on the earlier study carried out by the present authors (Bhargava et al. 2006). These formulations have further been used to analytically evaluate the ultimate bending moment and ultimate shear force capacity of the corroded concrete beams. Results of the present study indicate that, a considerably good agreement has been observed between the experimental and the analytically predicted values for the weight loss and reduction in radius of the corroded reinforcing bars. A considerably good agreement has also been observed between the experimental and the analytically predicted values of ultimate bending moment and ultimate shear force capacity for the corroded concrete beams.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.790-795
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• 2018

In this study, we analyzed the structural safety and vibration characteristics of rotational drive in 3D CT scan equipment using finite element analysis. The analysis results showed a safety factor of 9.2 and a left and right vertical deflectional deviation of 0.24mm from the maximum equivalent stress. After applying weight compensation of 27.7kgf, the structural analysis reduced the safety factor to 7.6, but the deflectional deviation of the left and right structure was reduced to 0mm. Also, we presented the optimum design of rotational drive through the vibration analysis.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.100-108
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• 2000

As U.S. congress and I.M.O. have recently adopted strengthened MARPOL73/78 regulations on marine pollution, it is necessary to develope a new type of tankers such as Double hull tanker(D/H Tanker) and Mid-deck tanker(M/D Tanker) and so on. Because most of researches are concentrated on the volume of oil spill due to collision of ships, in this paper, a structural design program for D/H Tankers and M/D Tankers is developed to suggest the effective type of tankers by comparing structural characteristics between their types. By this program, minimum hull weight designs of D/H tankers and M/D tankers considering tank arrangement are performed and the design results are compared each other. The efficient types of hull structure for the minimum weight design between D/H tankers and M/D tankers is proposed.

• Smart Structures and Systems
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• v.19 no.6
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• pp.643-652
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• 2017

Pitched roof frames are widely used in construction of the industrial buildings, gyms, schools and colleges, fire stations, storages, hangars and many other low rise structures. The weight and shape of the gable frames with tapered members, as a familiar group of the pitched roof frames, are highly dependent on the properties of the member cross-sectional. In this work Enhanced Colliding Bodies Optimization (ECBO) is utilized for optimal design of three gable frames with tapered members. In order to optimize the frames, the design is performed using the AISC specifications for stress, displacement and stability constraints. The design constraints and weight of the gable frames are computed from the cross-section of members. These optimum weights are obtained using aforementioned optimization algorithms considering the cross-sections of the members and design constraints as optimization variables and constraints, respectively. A comparative study of the PSO and CBO with ECBO is also performed to illustrate the importance of the enhancement of the utilized optimization algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.923-930
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• 2013

These days, the interests on the high speed handling robots are increasing because it is important to get down the unit cost of production to get the price competitiveness. The parallel kinematic mechanism is more suitable to implement the high speed robot system as well known. The moving parts of the high speed parallel robot have to be designed for light weight. But the vibration motion is induced by the light weight links because they drive in high acceleration and deceleration. In this reason, the structural analysis of the high speed parallel kinematic robot is very important in the design process. In this paper, the study on the structural analysis of a high speed parallel robot has been done and the research results will be introduced.