• 한국철도학회논문집
• /
• 제5권4호
• /
• pp.244-252
• /
• 2002

We must notice ground movement by excavation for reasonable tunnel designs. The convergence confinement method is an attempt to evaluate tunnel stability conditions by means of a mathematical model and a ground response curve. In this study, the convergence confinement method by numerical model was examined. This method don't need the basic assumptions for a mathematical model of circular tunnel shape, and hydrostatic in situ stress. Also modified ground response curve that is calculated after installing the support, is suggested, which informs us the ground movement mechanism. The ground response curve and the support reaction curve are mutually dependent. Especially the support reaction curve depends upon the ground response curve. The mechanism of tunnel must be analyzed by the interaction between support and ground. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

• 한국재난정보학회 논문집
• /
• 제3권1호
• /
• pp.69-86
• /
• 2007

The fire department has one of the most important role as public resources of response to disasters in the aspect of supply and the adequate distribution of resources of response is essential, but the distribution of the response capability to disaster of fire department does not reflect the regional hazard vulnerability and hazard risks. Researchers performed database process with simple mapping based on the regional fire disaster response capability and the regional hazard vulnerability and hazard risks. The cities and towns are divided to four types each, total eight types and relative threat ratios are extracted from every type. The fire disaster response capability was extracted from number of firemen and fire vehicles in defined region. The distribution of the fire disaster response capability was inadequate and not matching to relative threat especially in small cities and some types of towns. The regional relative threat and resources should be analyzed by more delicate mapping and software development in the future.

• Structural Engineering and Mechanics
• /
• 제22권4호
• /
• pp.469-481
• /
• 2006

A new method called fuzzy factor method for the stationary stochastic response analysis of fuzzy truss with global fuzzy structural parameters is presented in this paper. Considering the fuzziness of the structural physical parameters and geometric dimensions simultaneously, the fuzzy correlation function matrix of structural displacement response in time domain is derived by using the fuzzy factor method and the optimization method, the fuzzy mean square values of the structural displacement and stress response in the frequency domain are then developed with the fuzzy factor method. The influences of the fuzziness of structural parameters on the fuzziness of mean square values of the displacement and stress response are inspected via an example and some important conclusions are obtained. Finally, the example is simulated by Monte-Carlo method and the results of the two methods are close, which verified the feasibility of the method given in this paper.

• 설비공학논문집
• /
• 제15권6호
• /
• pp.480-488
• /
• 2003

The purpose of this research Is to derive the principal design parameters governing the dynamic characteristics of the high response flow control servo valve. For this purpose, a numerical modeling of the servo valve system and a parameter sensitivity analysis to a frequency response characteristics was peformed. As a result of these analysis, a basis for improvement of a dynamic characteristics of servo valve was arranged.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
• /
• pp.345-352
• /
• 1998

Free-field ground motion during earthquake is significantly affected by the local site conditions and the behavior of structure is influenced by ground motion, it is essential to perform the reliable site characterization and to determine the site specific earthquake response. In this study, case study of site specific ground response evaluation was performed at Inchon area. Step by step procedures for site characterization and one-dimensional site response analysis were introduced and the importance of site specific analysis was verified.

• 한국지진공학회논문집
• /
• 제12권6호
• /
• pp.65-71
• /
• 2008

본 논문에서는 반복하중에 의한 반복 경화 및 연화 현상을 나타낼 수 있는 수정 IWAN 모델을 이용하여, 1차원 비선형 부지응답 해석프로그램(이하 KODSAP; Kaist One Dimensional Site-response Analysis Program)을 개발하였다. 개발된 프로그램은 지진하중 재하에 따른 지반의 반복경화 및 연화현상에 의한 부지응답 특성 변화를 재현할 수 있다. KODSAP을 이용하여 기반암 상부 40m인 모형지반의 반복경화 및 연화 정도, 지진가속도의 크기에 따른 부지응답특성 변화를 살펴 보았으며, 현재 실무에서 널리 적용되고 있는 등가선형, 비선형해석과 KODSAP 해석결과(지반의 반복경화 및 연화현상을 고려한)과의 차이점을 살펴 보았다.

• 한국전산구조공학회논문집
• /
• 제15권1호
• /
• pp.21-32
• /
• 2002

일반적으로 응답스펙트럼 해석법은 건물의 지진해석에 널리 사용되고 있지만 기계하중이나 이동하중 등에 의하여 발생하는 진동에 대한 해석에는 시간이력해석이 주로 사용되고 있다. 그런데, 시간이력해석법은 정확한 반면 매우 복잡하고 어려우며 많은 시간을 필요로 한다. 따라서, 본 논문에서는 동적하중을 받는 구조물의 최대응답을 응답스펙트럼해석법을 이용하여 간편하게 계산하는 방법을 제시하고자 한다. 우선, 이 해석법의 해석과정에 대하여 알아보았으며, 복수절점에 동적 하중을 받는 경우에 대해서 해석시간 및 메모리를 줄이는 방법을 제시하였다. 다음으로는 이동하중을 받는 경우에 대하여 구조물의 최대응답을 구하는 방법에 대하여 알아보았다. 마지막으로 예제를 통하여 시간이력해석을 수행하여 얻은 최대응답과 응답스펙트럼해석에 의한 최대응답을 비교하여 제시한 해석법의 정확성을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제59권3호
• /
• pp.455-473
• /
• 2016

Methods for the seismic demands evaluation of structures require iterative procedures. Many studies dealt with the development of different inelastic spectra with the aim to simplify the evaluation of inelastic deformations and performance of structures. Recently, the concept of inelastic spectra has been adopted in the global scheme of the Performance-Based Seismic Design (PBSD) through Capacity-Spectrum Method (CSM). For instance, the Modal Pushover Analysis (MPA) has been proved to provide accurate results for inelastic buildings to a similar degree of accuracy than the Response Spectrum Analysis (RSA) in estimating peak response for elastic buildings. In this paper, a simplified nonlinear procedure for evaluation of the seismic demand of structures is proposed with its applicability to multi-degree-of-freedom (MDOF) systems. The basic concept is to write the equation of motion of (MDOF) system into series of normal modes based on an inelastic modal decomposition in terms of ductility factor. The accuracy of the proposed procedure is verified against the Nonlinear Time History Analysis (NL-THA) results and Uncoupled Modal Response History Analysis (UMRHA) of a 9-story steel building subjected to El-Centro 1940 (N/S) as a first application. The comparison shows that the new theoretical approach is capable to provide accurate peak response with those obtained when using the NL-THA analysis. After that, a simplified nonlinear spectral analysis is proposed and illustrated by examples in order to describe inelastic response spectra and to relate it to the capacity curve (Pushover curve) by a new parameter of control, called normalized yield strength coefficient (${\eta}$). In the second application, the proposed procedure is verified against the NL-THA analysis results of two buildings for 80 selected real ground motions.

• Structural Engineering and Mechanics
• /
• 제75권3호
• /
• pp.311-325
• /
• 2020

In applying the spectral stochastic finite element methods to the frequency response analysis, the conventional methods are known to give unstable and inaccurate results near the natural frequencies. To address this issue, a new sensitivity based stabilized formulation for stochastic frequency response analysis is proposed in this paper. The main difference over the conventional spectral methods is that the polynomials of random variables are applied to both numerator and denominator in approximating the harmonic response solution. In order to reflect the resonance behavior of the structure, the denominator polynomials is constructed by utilizing the natural frequency sensitivity and the random mode superposition. The numerator is approximated by applying a polynomial chaos expansion, and its coefficients are obtained through the Galerkin or the spectral projection method. Through various numerical studies, it is seen that the proposed method improves accuracy, especially in the vicinities of structural natural frequencies compared to conventional spectral methods.

• 한국해양공학회지
• /
• 제9권1호
• /
• pp.161-172
• /
• 1995

A numerical procedure is described fro predicting the motion and structural responses of tension leg platforms(TLPs) in waves. The developed numerical approach is based on a 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 tow-step analysis method. Both the hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural whole structure are formulated using element-fixed coordinate systems which have the origin at the node of the each hull element and move parallel to a space-fixed coordinate system. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, concerning the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.