• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.391-399
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• 2001

Three-dimensional dynamic analysis of underground openings subjected to explosive loadings considering the effects of water saturation is carried out in this study. The surrounding rock mass is assumed to be the limestone with 13.5% of porosity. Two calculations are compared using as identical explosive charge; the first in dry rock of 13.5% porosity, the second in the identical rock, but in a fully saturated condition. It is shown that velocity, displacement, and stress time histories are higher in saturated rock than those in dry rock through numerical studies. It is also shown that underground openings in saturated rock masses could be significantly more vulnerable to the potential damages associated with shear failure than those in dry medium.

• Journal of Ocean Engineering and Technology
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• v.7 no.1
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• pp.133-146
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• 1993

A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach is based on combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in usual two-step analysis method, proposed by Yoshida et. al. .The hydrodynamic interactions among TLP members, such as columms and pontoons, are included in the motion and structural analyses. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, of the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.35-38
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• 2010

본 논문에서는 flexible guideway 교량과 능동적으로 제어되는 자기부상 열차간의 동적 상호작용에 대한 수치해석 모델을 개발하였다. 중 저속 자기부상열차의 동적 응답에 대한 열차와 guideway 사이의 특성에 대한 연구를 실시하였다. 동적 지배방정식은 10자유도계의 자기부상열차 모델, guideway구조물의 모드 특성과 UTM02 부상제어모델을 결합함으로써 유도하였다. 수치해석으로부터 열차의 부상공극은 차량의 속도, 트랙조도의 영향을 크게 받는 것을 발견하였다.

• Computational Structural Engineering
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• v.8 no.1
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• pp.30-38
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• 1995

이방향 천공 발파공법의 실용성을 입증하여 실시공에 착수하기 위해서는 수치해석을 통하여 사전에 종방향 및 방사방향 천공발파에 따른 지표면에서의 지반진동의 영향을 알아보는 것이 필요하였다. 정확한 현장조건과 발파하중이 주어진 상태에서의 정밀해를 구하기 위해서는 시공상의 발파패턴대로 전체 발파공을 모형화하는 것이 필요하나 앞서 언급한 바와 같이 해석목적상 기존공법과 신공법의 지반응답의 차이를 비교하는 것이 주목적이였기 때문에 해석조건을 동일하게 가정하고 발파공도 대표적인 방향성을 가지는 1개공만을 선택하여 해석을 수행하였다. 기존 종방향 천공 발파공법과 신공법인 이방향 천공 발파공법의 상대적 비교를 위한 3차원 동적 해석결과, 관심의 대상이 되는 터널 직상부의 경우 기존의 종방향 천공 발파에 비해 이방향 천공발파는 진동이 두드러지게 감소함을 알 수 있었으며 이는 발파공의 방향성에 따라 지반응답이 크게 영향을 받는다는 것을 의미한다. 따라서 터널굴착시 문제시 되는 지상구조물의 위치에 따라 발파공의 위치를 적절히 조절함으로써 문제발생 예상지역의 진동치를 감소시킬 수 있을 것이라 판단된다. 그러나 이러한 잇점은 확대발파전 파이롯트 터널이라는 자유공간이 존재할 때만 가능하므로 이방향 천공 발파공법은 TBM의 효용성을 극대화시킨 것이라 할 수 있다.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.661-670
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• 2000

To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads, two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. Futhermore case of asymmetric traffic loading clustered in one direction are also considered to study the torsional response of the bridge. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• Journal of the Korean Geotechnical Society
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• v.37 no.12
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• pp.57-71
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• 2021

The pile-supported wharf is the port structure in which the upper deck is supported by piles or columns. By installing batter piles in this structure, horizontal load such as earthquake loads can be partially delivered as axial forces. The codes suggests using the response spectrum analysis as a preliminary design method for seismic design of pile-supported wharf, and suggests modeling the piles using virtual fixed points or soil spring methods for this analysis. Recently, several studies have been conducted on pile-supported wharves composed of vertical piles to derive a modeling method that appropriately simulates the dynamic response of structures during response spectrum analysis. However, studies related to the response spectrum analysis of pile-supported wharves with batter piles are insufficient so far. Therefore, this study performed the dynamic centrifuge model test and response spectrum analysis to evaluate the seismic performance according to the modeling method of pile-supported wharves with batter piles. As a result of test and analysis, it is confirmed that modeling using the Terzaghi (1955) constant of horizontal subgrade reaction (n_h) most appropriately simulates the actual response in the case of the pile-supported wharf with batter piles.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.51-58
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• 2008

Analytical probabilistic vulnerability analysis requires extensive computing effort as a result of the randomness in both input motion and response characteristics. In this study, a new methodology whereby a set of vulnerability curves are derived based on the fundamental response quantities of stiffness, strength and ductility is presented. A response database of coefficients describing lognormal vulnerability relationships is constructed by employing aclosed-form solution for a generalized single-degree-of-freedom system. Once the three fundamental quantities of a wide range of structural systems are defined, the vulnerability curves for various limit states can be derived without recourse to further simulation. Examples of application are given and demonstrate the extreme efficiency of the proposed approach in deriving vulnerability relationships.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.493-499
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• 2010

In the sea-floating logistics port called mobile harbor a crane system with the different structure from the conventional above-ground container crane is installed. And, the dynamic stability of whole mobile harbor by the wave excitation is definitely affected by the crane positioned at the top. This paper is concerned with the dynamic rolling analysis of the mobile harbor subject to sea state 3 wave excitation, for which two-step analysis procedure composed of theoretical and numerical approaches is employed. First, the rigid rolling of mobile harbor is obtained according to the linear wave theory. And then, the dynamic rolling response of the flexible crane system caused by the rolling excitation of mobile harbor is analyzed by finite element analysis. The coupled interaction effect between the sea wave and the mobile harbor is taken into consideration by the added mass technique.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.295-302
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• 2006

In this study, computational structural dynamic analyses of a gyrocopter have been conducted considering unsteady dynamic hub-loads due to rotating blades. 3D CATIA models with detailed mechanical parts we constructed and virtually assembled into the complete aircraft configuration. The dynamic loading generated by rotating blades in the forward flight condition are calculated by a commercial computational fluid dynamics (CFD) code such as FLUENT. Modal based transient and frequency response analyses are used to efficiently investigate vibration characteristics of the gyrocopter. Free vibration analysis results for different fuel and pilot conditions, frequency responses and transient responses for critical flight conditions are also presented in detail.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.2
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• pp.101-111
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• 2021

In general, several computational resources are required to perform multiple-loading transient response analyses. In this paper, we present the procedure for multiple-loading transient response analysis using the Krylov subspace model order reduction and Newmark's time integration scheme. We utilized ANSYS MAPDL, Python, and ANSYS ACT to automate the transient response analysis procedure in the ANSYS Workbench environment and studied several engineering numerical examples to demonstrate the feasibility and efficiency of the proposed approach.