• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.3-10
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• 1997

Meshless particle method is a numerical technique which does not use the concept of element. This method can easily handle special engineering problems which cause difficulty in the use of finite element method, however it has a drawback that essential boundary condition is not satisfied. In this paper, several studies for satisfying essential boundary conditions and enhancing the accuracy of solutions are discussed. Particular emphasis is placed on a new numerical technique in which finite elements are used on the boundaries to satisfy the essential boundary conditions and meshless particle method is used in the interior domain. For coupling of the two methods interface elements are introduced into the zone between the subdomains using meshless particle method and finite element method. The shape functions and the approximated displacement functions of the interface element are derived with the ramp function based on the shape function of finite elements. The whole numerical procedures are formulated by Galerkin method. Several numerical examples for enhancing the accuracy of solution in the meshless particle method and a new coupling method are presented.

• Land and Housing Review
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• v.3 no.2
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• pp.195-202
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• 2012

This paper summarizes the seismic performance of two shear walls with different reinforcement details in boundary elements. One is a special shear wall designed by KBC2009 and the other is a shear wall with improved reinforcement details in boundary elements, which is a newly proposed type of special shear wall. Experimental tests under cyclic reversed loading were carried out with two 2/3 scale shear walls which were modelled from the lower part of seismic-resisting shear wall in 22-stories wall-slab apartment building. The experimental results show that seismic performance of shear wall with improved reinforcement details was almost similar to that of special shear wall with respect to the moment-drift ratio. However, energy dissipation capacity and ductility were slightly different. Also, shear wall with improved reinforcement details in boundary elements satisfied the inter-story drift limit of 1.5% from KBC2009.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.137-144
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• 1994

In this study, a new procedure for solving 2-D dynamic problems of semi-infinite medium in time domain by boundary element method (BEM) is presented. Efficient modelling of the far field region, infinite boundary elements are introduced. The shape function of the infinite boundary element is a combination of decay functions and Laguerre functions. Though the present shape functions have been developed for the time domain analysis, they may be also applicable to the frequency domain analysis. Through the response analysis in a 2-D half space under a uniformly distributed dynamic load, it has been found that an excellent accuracy can be achieved compared with the analytical solution

• Computers and Concrete
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• v.2 no.2
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• pp.111-123
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• 2005

The ductility of reinforced concrete bearing walls subjected to high axial loading and moment can be enhanced by improving the deformability of the compression zone or by reducing the neutral axis depth. The current state-of-the-art procedure evaluating the confinement effect prompts a consideration of the spaces between the transverse and longitudinal reinforcing bars, and a provision of tie bars. At the same time, consideration must also be given to the thickness of the walls. However, such considerations indicate that the confinement effect cannot be expected with the current practice of detailing wall ends in Korea. As an alternative, a comprehensive method for dimensioning boundary elements is proposed so that the entire section of a boundary element can stay within the compression zone when the full flexural strength of the wall is developed. In this comprehensive method, the once predominant code approach for determining the compression zone has been advanced by considering the rectangular stress block parameters varying with the extreme compression fiber strain. Moreover, the size of boundary elements can also be determined in relation to the architectural requirement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.309-313
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• 2000

A structural-acoustic coupling problem involving fluid in a cavity divided with flexible walls and porous materials is investigated in this paper. In many practical problems, the use of finite elements to discretize the fluid region leads to large stiffness and mass matrices. But, since the acoustic boundary element discretization requires to put elements only on the surface of structure, the size of matrices is reduced considerably. Here, we developed a numerical analysis program for the structural-acoustic coupling problems of the multi-region cavity, using boundary elements for the fluid regions and finite elements for the structure. By considering sound transmission through layered systems placed in a cavity, the accuracy of the coupled acoustical-structural finite element model has been verified by comparing its transmission loss predictions with analytical sloutions. Example problems are included to investigate the characteristics of the multi-region structural-acoustic coupling system with porous material.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.11a
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• pp.216-219
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• 2007

New paradigm of modern society today - environmentally sound and sustainable development - led to the attempt on the introduction of natural elements in various spaces by people's interest in the quality of life. As one of the distinguished space marketing in designing the outer space of resort, this plan attempts to limit artificial boundary within open scenery, thus creating nature within nature - interior theme garden. In addition, this plan is aimed to obtain location property of inner garden through limited boundary, to promote the identity of resort by endowing it with new values in space and to form emotion care garden and culture garden for users. The plan has proceeded under the following concepts. 1) Differentiation from outer space has been made by creating a theme garden with unique theme garden - landscape elements and an attempt have been made to increase the values of interior garden through the introduction of new species of plants and the state-of-the-art facilities. 2) Emotion care garden - The garden has been created to get emotion purified systematically within nature and let people take a rest and enjoy their spare time. 3) Culture garden - The garden has been planned where culture could be created through various experience activities as a space with education and entertainment by providing a variety of interesting elements.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.45-53
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• 1991

The underground structure, which has infinite or semi-infinite boundary conditions, is subjected by body forces and in-situ stresses. It also has stress concentration, which causes material nonlinear behavior, in the vicinity of the excavated surface. In this paper, some methods which can be used to transform domain integrals into boundary integrals are reviewed in order to analyze the effect of the body forces and the in-situ stresses. First, the domain integral of the body force is transformed into boundary integral by using the Galerkin tensor and divergence theorem. Second, it is transformed by writing the domain integral in cylindrical coordinates and using direct integration. The domain integral of the in-situ stress is transformed into boundary integral applying the direct integral method in cylindrical coordinates. The methodology is verified by comparing the results from the boundary element analysis with those of the finite element analysis. Coupling the above boundary elements with finite elements, the nonlinear behavior that occurs locally in the vicinity of the excavation is analyzed and the results are verified. Thus, it is concluded that the domain integrals of body forces and in-situ stresses could be performed effectively by transforming them into the boundary integrals, and the nonlinear behavior can be reasonably analyzed by coupled nonlinear finite element and boundary element method. The result of this research is expected to he used for the analysis of the underground structures in the effective manner.

• Computers and Concrete
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• v.1 no.3
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• pp.285-302
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• 2004

A FE-(FE-HE)-BE procedure is presented for dynamic analysis of concrete arch dams. In this technique, dam body is discretized by solid finite elements, while the reservoir domain is considered by a combination of fluid finite elements and a three-dimensional fluid hyper-element. Furthermore, foundation rock domain is handled by three-dimensional boundary element formulation. Based on this method, a previously developed program is modified, and the response of Morrow Point arch dam is studied for various conditions. Moreover, the effects of canyon shape on response of dam, is also discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.290-297
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• 2000

A new form of construction utilizing structural steel as the boundary elements in ductile flexural concrete walls is proposed to solve the bar congestion problems associated with such a heavily reinforced region. Two wall specimens containing rectangular hollow structural sections(HSS) and channels at their ends respectively were constructed rectangular hollow structural sections(HSS) and channels ar their ends respectively were constructed and tested under reversed cyclic loading to evaluate the construction process as well as the structural performance. One companion standard reinforced concrete wall specimen was also tested for the comparison purpose At an Initial stage all three specimens were carefully detailed to have the approximately same flexural capacity. Analysis and comparison of test results indicated that the reversed cyclic responses of the three walls showed similar hysteretic properties but in those with steel boundaries local bucking of the corresponding steel elements following significant yielding of structural steel was prominent. Design procedures considering local instability of the structural steel elements and the interaction between steel chord and concrete web members in such composite walls are presented.

• Computational Structural Engineering
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• v.6 no.4
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• pp.89-98
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• 1993

As the construction of nuclear power plants are increased, nuclear wastes disposal has been faced as a serious problem. If nuclear wastes are to be buried in the underground stratum, thermo-mechanical behavior of stratum must be analyzed, because high temperature distribution has a significant effect on tunnel and surrounding stratum. In this study, in order to analyze the structural behavior of the underground which is subject to concentrated heat sources, a coupling method of nonlinear finite elements and linear boundary elements is proposed. The nonlinear finite elements (NFE) are applied in the vicinity of nuclear depository where thermo-mechanical stress is concentrated. The boundary elements are also used in infinite domain where linear behavior is expected. Using the similar method as for the problem in mechanical field, the coupled nonlinear finite element-boundary element (NFEBE) is developed. It is found that NFEBE method is more efficient than NFE which considers nonlinearity in the whole domain for the nuclear wastes depository that is expected to exhibit local nonlinearity behavior. The effect of coefficients of the rock mass such as Poisson's ratio, elastic modulus, thermal diffusivity and thermal expansion coefficient is investigated through the developed method. As a result, it is revealed that the displacements around tunnel are largely dependent on the thermal expansion coefficients.