• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.11-21
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• 2000

구조물에 내진설계를 적용하는 목적은 지진에 노출되는 구조물에 안전성과 경제성을 고려한 파괴메카니즘을 부여하는 것이다. 내진설계에 보편적으로 적용하고 있는 응답스펙트럼해석법은 선형해석법으로 구조물의 비선형 동적거동에 의한 영향은 특정 계수로 반영한다. 그러나 기존의 내진설계시방서들이 강진지역에 있는 나라들에 의해 제정 및 개정되어 왔기 때문에 응답스펙트럼 해석법 뿐만 아니라 기타의 적용규정이 강진지역에 위치한 구조물의 상황만을 고려하여 제시되었다. 따라서 중약진지역에 위치한 구조물의 내진설계에 대한 별도의 연구가 요구되고 있다. 이 연구에서는 중약진지역에 위치한 콘크리트 교량을 선정하여 비선형 동적거동을 반영하는 계수를 결정하고 응답스펙트럼 해석법을 적용하였다. 연구 결과 바탕으로 중약진지역의 교량에 대해 내진설계의 목적을 만족하는 개선된 내진설계 절차를 제시하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.1-11
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• 2001

The purpose of this study is to develop the main program and pre/post processor for the geometric and plastic non-linear analysis of steel jacket structures subjected to wave and earthquake loadings. In this paper, steel jackets are modelled using geometric non-linear space frames and wave loadings re evaluated based on Morrison equation using the linear Airy theory and the fifth Stokes theory. Random wave is generated using JONSWAP spectrum. For earthquake analysis, dynamic analysis is performed using artificial earthquake time history. Also the plastic hinge method is presented for limit analysis of steel jacket. In the companion paper, the pre/post processor is developed and the numerical examples are presented for linear and non-linear dynamic analysis of steel jackets.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.4
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• pp.3-15
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• 2001

Generally, it has been noted that underground structures have a consistent record of suffering much less damage than surface facilities during earthquakes; but it is still necessary to illustrate the dynamic response of tunnel structures subject to earthquake loadings and to provide the appropriate method for the seismic analysis of underground tunnel structures since many types of underground structures have been and will be constructed in countries situated within seismic zones. In this study, first, seismic analyses for underground tunnel structures are performed by using quasistatic analysis method and dynamic analysis method. Second, seismic analyses in tunnel portals are performed by using above methods. The results of seismic analyses for the tunnel structure show that the tunnel structure conforms to ground deformation and that seismic design by using the quasi-static analysis method is more conservative than that by using the dynamic analysis. The results of the dynamic FEM analysis for the tunnel structure show that the simplified 2-D FEM analysis using a sine wave rather than the 3-D FEM analysis can be adopted for seismic analysis. Finally, the results of the dynamic FEM analysis in tunnel portals show that the force acting on the lining is largest near to the tunnel portal when an earthquake wave propagates parallel to tunnel axis.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.2
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• pp.90-103
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• 1997

A numerical procedure is described for predicting the motion and structural responses of the very large floating offshore structures supported by multiple 3-D floating bodies of arbitrary shape in multi-directional irregular waves. The developed numerical approach taking into account of the hydrodynamic interactions among the multiple floating bodies is based on a combination of the 3-D source distribution method, the wave interaction theory, the finite element method and the spectral analysis method to get the significant values of the dynamic responses in the multi-directional irregular waves. The effects of wave interactions and directionality on the dynamic responses of a very large offshore structure, which is semisubmersible ring type, are numerically examined.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.600-606
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• 2006

실제 지반은 경계가 없는 무한상태로 존재하기 때문에 지반구조물의 동적거동을 유한요소법을 이용하여 해석할 시 모델의 영역을 성립하는 것은 특별한 고려가 필요하다. 유한요소법에서의 동적해석은 파동의 전달을 포함하기 때문에 모델의 경계에서 인공적인 경계조건이 필요하다. 인공적인 경계 조건은 유한요소내의 지반상태를 무한상태로 변형시킬 수 있어야 하며, 경계에 도달하는 응력 파동을 모델내로 반사시키지 않고 흡수 할 수 있어야 한다. 본 논문에서는 간단한 점 탄성 반무한 불연속 요소를 이용하여 지반구조물의 동적해석을 수행하는 방법을 보여준다. 반무한 요소의 실행은 OpenSees라는 유한요소 해석프로그램을 이용하여 수행되었으며, 예를 통하여 불연속 요소가 경계에 도달하는 응력 파동을 충분히 흡수하여 유한요소 모델을 반무한 상태로 전환 시킬 수 있다는 것을 보여준다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.413-422
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• 2001

In this study, the effect of hydrodynamic masses is investigated in the dynamic characteristics and earthquake response analyses of the submerged HANARO flow tubes. First, the consistent hydrodynamic masses of the surrounding water are obtained by finite element method. Then, modal analyses and response spectrum analyses are performed and verified by comparing the results with those measured from an experiment. Arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered by using the general benefits of a finite element method comparing with the conventional analytical methods. Practical criteria based on parametric studies are proposed to evaluate the dynamic characteristics of HANARO flow tubes including the hydrodynamic masses.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.169-178
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• 1998

In general, the response spectrum analysis method is widely used for seismic analysis of building structures, and the time history analysis is applied for computation of structural vibration caused by equipments, machines and moving loads, etc. However, compared with the response spectrum analysis method, the time history method is very complex, difficult and time consuming. In this study, the maximum responses for the vertical vibration are calculated conveniently by the response spectrum method. At first, Response spectrum and time history analysis for some earthquake excitations are carried out, and the accuracy of maximum displacements obtained from response spectrum analysis is investigated. Secondly, the process for the response spectrum analysis in excitation is calculated, and the maximum modal responses are combined by CQC method. Finally, results of the proposed method are compared with those of the time history analysis.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.59-66
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• 2001

구조물 내진설계의 개념은 기존요구조건이라는 조항으로 시방서에 규정되어 있으며 구조물이 지진발생시에 안전성과 경제성을 최대한 확보할 수 있으며 비선형시간 이력해석을 수행하여 자진시의 동적거동을 기술함으로써 확인할 수 있다. 내진설계에 보편적으로 적용하는 응답스펙트럼해석법은 선형해석법으로 구조물의 비선형동적거동의 영향을 거동계수로 반영하므로 파괴메카니즘 및 기본 요구조건의 만족여부를 거동계수를 구하는 과정으로 결정할 수 있다. 이 연구에서는 내진설계방식에 의해 설계된 약진지역에 의한 화학공장건물의 모델인 3차원 철골뼈대구조물을 선정하고 거동계수를 결정하는 과정을 수행하여 지진시의 동적거동을 확인하였다. 이 연구의 결과, 현 시방서의 응답스펙트럼해석법에 적용되는 거동계수는 강진지역의 구조물의 경우 기능성 및 안정성 한계를 제시하지만 약진지역 구조물의 경우는 실제 동적거동과 무관하다는것과 약진 지역에 위치한 구조물의 내진설계에는 시방서가 제시한 내진설계방식을 적용하는 것이 주요한 사항임을 확인하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.23-28
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• 2010

Reliable dynamic analysis is essential in order to properly maintain structures so that structural hazards may be minimized. The finite element method (FEM) is proven to be an affective approximate method of structural analysis if proper element types and meshes are chosen. When the method is applied to dynamics analyzed in time domain, the meshes may need to be modified at each time step. As many meshes need to be generated, adaptive mesh generation schemes have become an important part in complex time domain dynamic finite element analyses of structures. In this paper, an adaptive mesh generation scheme for dynamic finite element analyses of structures is described. The concept of representative strain value is used for error estimates and the refinements of meshes use combinations of the h-method (node movement) and the r-method (element division). The validity of the scheme is shown through a cantilever beam example under a concentrated load with varying values. The example shows reasonable accuracy and efficient computing time. Furthermore, the study shows the potential for the scheme's effective use in complex structural dynamic problems such as those under seismic or erratic wind loads.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.2
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• pp.139-148
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• 2012

The MLS(Moving Least Squares) Difference Method is a numerical scheme that combines the MLS method of Meshfree method and Taylor expansion involving not numerical quadrature or mesh structure but only nodes. This paper presents an dynamic algorithm of MLS difference method for solving transient solid mechanics problems. The developed algorithm performs time integration by using Newmark method and directly discretizes strong forms. It is very convenient to increase the order of Taylor polynomial because derivative approximations are obtained by the Taylor series expanded by MLS method without real differentiation. The accuracy and efficiency of the dynamic algorithm are verified through numerical experiments. Numerical results converge very well to the closed-form solutions and show less oscillation and periodic error than FEM(Finite Element Method).