• Title/Summary/Keyword: Time history

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The Effects of Stress and Time History on Pore Pressure Parameter of Overconsoldated clay (과압밀점토의 간극수압계수에 응력이력과 시간이력이 미치는 영향)

  • 김수삼;김병일;한상재;신현영
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.4
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    • pp.286-294
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    • 2002
  • This study investigated the effects of stress and time history of overconsolidated clayey soils on pore pressure parameter, A. Laboratory tests were carried out under the conditions of both varying stress and time history. The stress history is classified into (i) rotation angle of stress path, (ii) overconsolidation ratio, and (iii) magnitude of length of recent stress path. The time history is divided into (i) loading rate of recent stress path and (ii) rest time. Pore pressure parameters are different both in the magnitude and trend with the rotation angle, depending on the magnitude of overconsolidation ratio but not in a trend. In addition, the pore pressure parameters have no effects on the magnitude of length of recent stress path except the level of initially small strain, while loading rates of recent stress path have effects on it. Finally, the pore pressure parameters of overconsolidated clays increase with the existence of the rest time, until either the deviator stress exceeds 70 kPa or the strain up to 0.1%.

Generation of Artificial Time History Covering Design Response Spectrum by Two Modification Functions (이중 수정함수 적용을 통한 설계응답스펙트럼 포괄 인공지진파의 생성)

  • Park, Gun;Hong, Ki Nam;Han, Sang Hoon;Kim, Jae Suk
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.1
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    • pp.1-11
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    • 2016
  • The domestic and foreign seismic design codes have specified that time history covers design response spectrum when the response spectrum, which calculated from the time history, is smaller than the design response spectrum at five points or less. In order to verify the design codes, time history analysis for a pier was performed by using five artificial time histories conforming design code with various characteristics and its member forces were evaluated according to them. It was confirmed from analysis results that, regardless of the conformity to design code requirement, seismic design using the artificial time histories could not guarantee earthquake resistant design if the response spectrum from them is lower than design response spectrum at the similar period to the natural frequency of structure. Thus, the time history generating method to make its acceleration response spectrum to be greater than design response spectrum at all period was proposed by two modification function in this study. It was also verified whether time histories from the proposed method satisfy the seismic design codes or not.

Criticism of the 『History of Korean Medicine』 written by Kim Doo Jong (김두종(金斗鍾)의 상세의학사(上世醫學史) 비판(批判))

  • Park, Seong Kue;Kim, Nam Il
    • The Journal of Korean Medical History
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    • v.20 no.1
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    • pp.68-82
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    • 2007
  • Kim, Doo-jong wrote "History of Korean Medicine", which was based on the historical view of Japanese Imperialism, insisting that Korea had stagnated and should be stimulated by others because it had no ability to improve by itself. To meet his opinion, he distorted and fabricated Korean Medical History to justify his past and work as Lee, Byung-Do did on Korean History. This paper intended to reveal his distortion and fabrication on the ancient Korean Medical History. Firstly, he insisted that Korean medicine had stagnated till other neighbor medicine, that is, Chinese medicine, Indian medicine, Japanese medicine and European medicine stimulated its progress. Secondly, he insisted that the Korea peninsula has been the Korean territory all through its history, which was originally forged by the Japanese Imperialists. He adopted this theory to justify his past and work. Thirdly, he insisted that Korea was effected by the European medicine a long time ago. Even though the European medicine was not skillful at that time compared with Korean medicine, he adopted this theory to justify his past and work. Lastly, he had a wrong recognition on culture and religion, which he just used to justify his past and work. Profound study and research are required to eliminate his distortion and write the history of Korean medicine correctly.

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The Estimation of the Floor Vibration in Structure for Application of Response Spectrum Analysis Method (응답스펙트럼 해석법을 이용한 건축 구조물의 바닥진동해석)

  • 이동근;김태호
    • 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.

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Time History Analysis of Sturctures Subjected to Random Base Excitation by a Substructuring Method (부구조법을 이용한 불규칙 기초가진을 받는 구조물의 시간 이력 해석)

  • Lee, Tae Won
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.3
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    • pp.86-91
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    • 2022
  • The mechanical structures mounted on vehicles or aircrafts are subject to random accelerations, such as earthquakes, at the base, and their responses have been calculated through spectrum analysis. However, this method poses a challenge during the synthesis of the responses owing to the loss of the vibration phase. It is necessary to evaluate the time history results to obtain the exact responses; therefore, an efficient technique is proposed to solve this issue. The present technique involves constructing a superelement using the sub-structuring method and finding solutions for this superelement. The finite element model (FEM) was substituted by a superelement, which was simplified into one element with selected nodes. Comparing the numerical results of the superelement with the time history responses for the original finite element model, the two solutions agree well despite the fact that the computation time of the proposed technique has been greatly shortened.

A History of Taylor's Theorem and Its Teaching Strategy (Taylor 정리의 역사적 고찰과 교수방안)

  • Kim, Sung-Ock
    • Journal for History of Mathematics
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    • v.31 no.1
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    • pp.19-35
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    • 2018
  • Taylor's Theorem is an important theorem which is applied to several disciplines. It is usually taught in a college-level calculus course for the first time. Many students have a hard time to understand or to make applications. In this paper, we look into the history of the development of Taylor's theorem and consider a teaching strategy of the theorem.

Seismic Analysis of 3D-Truss by Response Spectrum (응답스펙트럼에 의한 트러스 구조물의 내진해석)

  • 안주옥;이승재
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.04a
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    • pp.159-168
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    • 1999
  • In seismic analysis, there are two main ways - uniform load method and dynamic analysis, dynamic analysis can be divided into response spectrum analysis and time history analysis. In case of which get the complexion of the vibration with 3-axis of coordinate direction in each mode of free vibration mode happened owing to complication of the shape, 3-dimensional dynamic analysis is recommended to perform as multi-mode spectral analysis in standard specification for highway bridge. The purpose of this study is to understand the dynamic behavior by performing multi-mode seismic analysis according to responses analysis and time history anal)'sis in using record of earthquake. In accordance with the criterion of seismic design as defined in standard specification for highway bridge by using modified records of the El Centre and Coyote Lake earthquake, response spectrum was constructed by using the tripartite logarithmic plot. The 3-span continuous space truss bridge was selected as model of numerical analysis. As the result performed time history analysis and analysis of response spectrum for the model of numerical analysis, the result of time history analysis was slightly larger than that of response spectrum analysis. This coincide with the tendency of the result came from the analysis when using a jagged response spectrum analysis, This coincide with the tendency of the result came from the analysis when using a jagged response spectrum for a single excitation. In the Process of performing these two analysis. response spectrum analysis is more effective than time history analysis in saving times in analyzing data.

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Time-history analysis based optimal design of space trusses: the CMA evolution strategy approach using GRNN and WA

  • Kaveh, A.;Fahimi-Farzam, M.;Kalateh-Ahani, M.
    • Structural Engineering and Mechanics
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    • v.44 no.3
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    • pp.379-403
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    • 2012
  • In recent years, the need for optimal design of structures under time-history loading aroused great attention in researchers. The main problem in this field is the extremely high computational demand of time-history analyses, which may convert the solution algorithm to an illogical one. In this paper, a new framework is developed to solve the size optimization problem of steel truss structures subjected to ground motions. In order to solve this problem, the covariance matrix adaptation evolution strategy algorithm is employed for the optimization procedure, while a generalized regression neural network is utilized as a meta-model for fitness approximation. Moreover, the computational cost of time-history analysis is decreased through a wavelet analysis. Capability and efficiency of the proposed framework is investigated via two design examples, comprising of a tower truss and a footbridge truss.

Evaluation of the Relationship Between Possible Earthquake Time History Shape Occurring in a Target Fault Using Pseudo-Basis Function (유사기저함수를 사용한 대상 단층에서 발생 가능 지진파 형태 사이의 관계 표현 방법 개발 및 포항 단층과 경주 단층 발생 지진에의 적용)

  • Park, Hyung Choon;Oh, Hyun Ju
    • Journal of the Earthquake Engineering Society of Korea
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    • v.27 no.3
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    • pp.139-145
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    • 2023
  • It is essential to determine a proper earthquake time history as a seismic load in a seismic design for a critical structure. In the code, a seismic load should satisfy a design response spectrum and include the characteristic of a target fault. The characteristic of a fault can be represented by a definition of a type of possible earthquake time history shape that occurred in a target fault. In this paper, the pseudo-basis function is proposed to be used to construct a specific type of earthquake, including the characteristic of a target fault. The pseudo-basis function is derived from analyzing the earthquake time history of specific fault harmonic wavelet transform. To show the feasibility of this method, the proposed method was applied to the faults causing the Gyeong-Ju ML5.8 and Pohang ML5.3 earthquakes.

Generation of Simulated Earthquakes and Time-history Dynamic Analysis of Containment Building (지진 데이터 생성 및 격납건물 시간이력 해석)

  • 배용귀;이성로
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.608-612
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    • 2003
  • In the seismic response analysis, the artificial earthquake time history is generated to do the exact seismic analysis for the complex structural system like as containment building. In the present study the several simulated earthquakes are generated by use of SIMQKE program and the time history dynamic analysis of containment building is performed. Also, the seismic responses are statistically analyzed. The seismic response uncertainty arisen from the simulation of earthquakes is one of major uncertainties and the statistical description is needed to account for the random nature of earthquake.

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