• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2002년도 추계 학술발표회 논문집
• /
• pp.106-113
• /
• 2002

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used for a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted for soil. These two fields are coupled using FE-BE coupling technique In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, the dynamic response analyses of interface spring elements are performed. As a result, less spring stiffness makes the natural frequency decrease and the resonant amplitude increase.

• Coupled systems mechanics
• /
• 제9권1호
• /
• pp.29-46
• /
• 2020

In this paper we deal with stability problems of any complex structure that can be modeled by beam and shell finite elements. We use for illustration the steel plate girders, which are used in bridge construction, and in industrial halls or building construction. Long spans, slender cross sections exposed to heavy loads, are all critical design points engineers must take into account. Knowing the critical load that will cause lateral torsional buckling of the girder, or load that can lead to web buckling, as an important scenario to consider in a design process.Many of such problem, including lateral torsional buckling with influence of lateral supports and their spacing on critical load can be solved by the proposed method. An illustrative study of web buckling also includes effects of position and spacing of transverse and longitudinal web stiffeners, where stiffeners can be modelled optionally using shell or frame elements.

• 대한기계학회논문집A
• /
• 제29권7호
• /
• pp.990-997
• /
• 2005

The objective of this paper is to present the element connectivity parameterization (ECP) fur three dimensional problems. In the ECP method, a continuum structure is viewed as discretized finite elements connected by zero-length elastic links whose stiffness values control the degree of inter-element connectivity. The ECP method can effectively avoid the formation of the low-density unstable elements. These elements appear when the standard element density method is used for geometrical nonlinear problems. In this paper, this ECP method developed fur two-dimensional problems is expanded to the design of three-dimensional geometrical nonlinear structures. Among others, the automatic procedure converting standard finite element models to the models suitable for the ECP approach is developed and applied for optimization problems defined on general three-dimensional design domains.

• 대한기계학회논문집A
• /
• 제21권12호
• /
• pp.1973-1983
• /
• 1997

Higher order isoparametric elements are usually used in the finite element analysis because they can represent easily the geometric shape of a complex structure ad can improve the solution quality. When these elements are used, the position of internal nodes affects greatly on the solution accuracy. Decreasing of the accuracy related to the position of internal nodes is due to non-conformal mapping often results in an unstable Jacobian value. This paper, in order to remove this difficulty, suggests a modified shape function which can establish conformal mapping between two coordinate systems. Numerical experiments with the proposed shape function show that a stable solution can be obtained without respect to the position of internal nodes, and offer convenience that one can take arbitrarily the position of internal nodes considering only the geometric shape of element boundaries.

• Coupled systems mechanics
• /
• 제6권4호
• /
• pp.501-522
• /
• 2017

This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.

• Computers and Concrete
• /
• 제15권4호
• /
• pp.547-562
• /
• 2015

A two-dimensional multi-layered finite elements modeling of reinforced concrete structures at non-linear behaviour under monotonic and cyclical loading is presented. The non-linearity material is characterized by several phenomena such as: the physical non-linearity of the concrete and steels materials, the behaviour of cracked concrete and the interaction effect between materials represented by the post-cracking filled. These parameters are taken into consideration in this paper to examine the response of the reinforced concrete structures at the non-linear behaviour. Four examples of application are presented. The numerical results obtained, are in a very good agreement with available experimental data and other numerical models of the literature.

• Structural Engineering and Mechanics
• /
• 제40권6호
• /
• pp.829-845
• /
• 2011

This paper evaluates the effects of topographical and geotechnical irregularities on the dynamic response of the 2-D soil-structure systems under ground motion by coupling finite and infinite elements. A numerical procedure is employed, and a parametric study is carried out for single-faced slope topographies. It is concluded that topographic conditions may have important effects on the ground motion along the slope. The geotechnical properties of the soil will also have significantly amplified effects on the whole system motion, which cannot be neglected for design purposes. So, dynamic response of a soil-structure systems are primarily affected by surface shapes and geotechnical properties of the soil. Location of the structure is another parameter affecting the whole system response.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
• /
• pp.262-264
• /
• 2000

A numerical method for the analysis of 3D eddy current in conductors due to applied time varying field is suggested using the finite element method. In the approximation of the field quantifies, the edge element is used, because it reduce the required computer memory and the computing time compared with the nodal elements. With edge elements, furthermore, the field governing equations become simple because the electric scalar potential ${\phi}$ can be set to zero. The modified magnetic vector potential($A^*$) is used as a state variable. The analysed results are compared with the experimentally measured ones for the TEAM workshop problem3.

• 지질공학
• /
• 제6권3호
• /
• pp.119-130
• /
• 1996

경계요소법을 이용한 2차원 전기비저항 모델링을 위한 이론적 전개와 수치계산 기술이 주어졌다. 균질 지하모델과 층상구조 지하모델에 대한 점전류전원에 대한 전위분포가 경계요소법을 이요하여 계산되으며, 그 결과는 동일 모델에 대해서 수행된 유한차분법, 유한요소법의 수치 결과와 비교 연구되었다. 경계요소법을 사용한 2차원 전기모델링은 저장용량, 계산속도 및 정확도에서 유한요소법이나 유한차분법에 비해 효율적임이 입증되었다.

• Computers and Concrete
• /
• 제23권1호
• /
• pp.25-36
• /
• 2019

In this paper, an algorithm is presented to simulate numerically the reinforced concrete (RC) columns having any geometric form of section, loaded eccentrically along one or two axes. To apply the algorithm, the columns are discretized into two macro-elements (MEs) globally and the critical sections of columns are discretized into fixed rectangular finite elements locally. A proposed triple simultaneous dichotomy convergence method is applied to find the equilibrium state in the critical section of the column considering the three strains at three corners of the critical section as the main characteristic variables. Based on the proposed algorithm a computer program has been developed for simulation of the nonlinear behavior of the eccentrically-loaded columns. A good agreement has been witnessed between the results obtained applying the proposed algorithm and the experimental test results. The simulated results indicate that the ultimate strength and stiffness of the RC columns increase with the increase in axial force value, but large axial loads reduce the ductility of the column, make it brittle, impose great loss of material, and cause early failure.