• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.537-550
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• 2017

Structural sizing is a rewarding task due to its non-convex constrained nature in the design space. In order to provide both global exploration and proper search refinement, a hybrid method is developed here based on outstanding features of Evolutionary Computing and Teaching-Learning-Based Optimization. The new method introduces an observer phase for memory exploitation in addition to vector-sum movements in the original teacher and learner phases. Proper integer coding is suited and applied for structural size optimization together with a fly-to-boundary technique and an elitism strategy. Performance of the proposed method is further evaluated treating a number of truss examples compared with teaching-learning-based optimization. The results show enhanced capability of the method in efficient and stable convergence toward the optimum and effective capturing of high quality solutions in discrete structural sizing problems.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.173-183
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• 2014

Nakanoshima Festival Tower is a 200 m high-rise complex building which contains a renewed 2700-seat capacity concert hall known as "Festival Hall" and offices including headquarter of a news company. In order to build up an office tower on the hall which requires large open space, a giant truss system is employed. The giant trusses being composed of mega-trusses and belt-trusses support all the building weight above them and transfer the load to the outside of the hall. The building also requires high seismic resistance performance for a news company. Application of mid-story seismic isolation enables the building to satisfy high-level seismic resistance criteria.

• Journal of Mechanical Science and Technology
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• v.15 no.8
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• pp.1132-1142
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• 2001

The paper describes the construction of global function approximation models for use in design optimization via global search techniques such as genetic algorithms. Two different approximation methods referred to as evolutionary fuzzy modeling (EFM) and neuro-fuzzy modeling (NFM) are implemented in the context of global approximate optimization. EFM and NFM are based on soft computing paradigms utilizing fuzzy systems, neural networks and evolutionary computing techniques. Such approximation methods may have their promising characteristics in a case where the training data is not sufficiently provided or uncertain information may be included in design process. Fuzzy inference system is the central system for of identifying the input/output relationship in both methods. The paper introduces the general procedures including fuzzy rule generation, membership function selection and inference process for EFM and NFM, and presents their generalization capabilities in terms of a number of fuzzy rules and training data with application to a three-bar truss optimization.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.104-111
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• 1995

The needs of ultraprecision machine tools, which manufacture and machine the high precision parts used in computers, semiconductors and othe rprecise machines, have been increased recentrly. So it is important to design the driving parts of the ultraprecision machine tools which affect significantly on the performance of them. In this paper, the dynamic analyses on the belt-drive system were studied. The correlational equations between the acoustic natural frequency and the tension of belt were derived by experiments. The dynamic delections while the dynamic loads on the motor system changed were analyzed by the finite element analysis. The nonlinear characteristics of the bearings on the dynamic performance was studied and the belt connecting the motor to the spindle of a machine tool was modeled by the truss element and the beam element.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.720-728
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• 2006

A robust damage assessment technique is presented such that the location and severity of damage in structures can be identified using measured modal data. In order to identify the damage efficiently, the concept of design of experiment using orthogonal array is used for screening the main effects of each parameter which corresponds to possible damage location in FE model. Then, Taguchi method, which has been widely used for robust design in industry, is applied to parameter updating in analytical FE model. The numerical simulations of a truss structure show that damages in structure can be located from updated parameters.

• Smart Structures and Systems
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• v.18 no.4
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• pp.733-754
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• 2016

Structural optimization involves a large number of structural analyses. When optimizing large structures, these analyses require a considerable amount of computational time and effort. However, there are specific types of structure for which the results of the analysis can be achieved in a much simpler and quicker way thanks to their special repetitive patterns. In this paper, frequency constraint optimization of cyclically repeated space trusses is considered. An efficient technique is used to decompose the large initial eigenproblem into several smaller ones and thus to decrease the required computational time significantly. Some examples are presented in order to illustrate the efficiency of the presented method.

• Computers and Concrete
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• v.19 no.5
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• pp.589-597
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• 2017

Strut-and-tie modeling method, which evolved on truss-model approach, has generally been preferred for the design of complex reinforced concrete structures and structural elements that have critical shear behavior. Some structural members having disturbed regions require exceptional detailing for all support and loading conditions, such as the beam-column connections, deep beams, short columns or corbels. Considering the general expectation of exhibiting brittle behavior, corbels are somewhat dissimilar to other shear critical structures. In this study, reinforcement layout of a corbel model was determined by the participation of structural optimization and strut-and-tie modeling methods, and an experimental comparison was performed against a conventionally designed model.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.441-458
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• 2012

The shear strength is an important factor in the design of prestressed concrete beams. Therefore, researchers have utilized various methods to determine the shear strength of these elements for the design purposes. To evaluate some of the proposed theoretical methods, numerous models of post-tensioned beams with or without vertical prestressing are selected and analyzed using the finite element method and assuming nonlinear behavior for the materials. In this regard the validity of modeling is evaluated based on some tests results. In the second part of the study two beam specimens are built and tested and their load-deformation curve and cracking pattern are studied. The analytical results consist of compressive strut slope and mid span load deflection are compared with some experimental results, and the results of some codes' formulas. Finally comparing the results of nonlinear analysis with the experimental values, a new formula is proposed for determining strut slopes in prestressed concrete beams.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.434-441
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• 1999

The newly proposed Precast Segmental Mettled (PSM), which makes use of precast elements for election, is relatively new, efficient and fast mettled for the construction of prestressed box girder bridges. A precast segment of 25m long pretensioned in the fabrication yard is transported by a special trailer and a launching truss to its final position. The segments are then connected in the site by post-tensioning to make a continuous prestressed concrete box girder bridges. The purpose of this parer is to analyze and evaluate the design of precast prestressed concrete box girder bridges. The detailed analyses including time-dependent behavior of PSM bridges are conducted. The major results and findings, which have been obtained from finite element analysis of PSM bridge, are discussed in this paper and these results will be a good base for the design and analysis of a new precast bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.295-302
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• 2002

This paper introduces a method to determine strut-tie models in reinforced concrete (RC) structures using the evolutionary structural optimization (ESO). Even though strut-tie models are broadly adapted in design of reinforced concrete members subjected to shear and torsion, conventional methods can hardly give correct models in RC members subjected to complex loadings and geometry conditions. In this paper, the basic idea of the ESO method is used to determine more rational strut-tie models. Since an optimum topology of structures, finally obtained by the ESO method, usually represents a truss-like structure, the ESO method can effectively be used in finding the best strut-tie model in RC structures. Several example structures are provided to demonstrate the capability of the proposed method in finding the best strut-tie model of each RC structure and to verify its efficiency in application to real design problems.