• Title, Summary, Keyword: time history analysis

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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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    • 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.

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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Reduced record method for efficient time history dynamic analysis and optimal design

  • Kaveh, A.;Aghakouchak, A.A.;Zakian, P.
    • Earthquakes and Structures
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    • v.8 no.3
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    • pp.639-663
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    • 2015
  • Time history dynamic structural analysis is a time consuming procedure when used for large-scale structures or iterative analysis in structural optimization. This article proposes a new methodology for approximate prediction of extremum point of the response history via wavelets. The method changes original record into a reduced record, decreasing the computational time of the analysis. This reduced record can be utilized in iterative structural dynamic analysis of optimization and hence significantly reduces the overall computational effort. Design examples are included to demonstrate the capability and efficiency of the Reduced Record Method (RRM) when utilized in optimal design of frame structures using meta-heuristic algorithms.

Using integrated displacement method to time-history analysis of steel frames with nonlinear flexible connections

  • Hadianfard, M.A.
    • Structural Engineering and Mechanics
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    • v.41 no.5
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    • pp.675-689
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    • 2012
  • Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

A Method of Selecting Ground Motions for Three-Dimensional Dynamic Analysis of Structures (구조물의 3차원 시간이력해석을 위한 지진파 결정 방법)

  • Ha, Seong Jin
    • Journal of the Architectural Institute of Korea
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    • v.36 no.8
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    • pp.145-151
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    • 2020
  • Dynamic analyses such as response spectrum analysis or time history analysis of structures have been performed to assess the structural demands for earthquake loads. For time history analysis, it is very important to select appropriate input ground motions with construction of numerical models of structures that reflects the non-linearity of the structure. In particular, three-dimensional dynamic analyses are required for skyscrapers or irregular buildings, according to seismic design codes. Current seismic design codes require that two-dimensional time history analysis of a structure should be analyzed using three or more horizontal component ground motions. For three-dimensional analysis, at least three seismic records each consisting of two horizontal components are required. In this study, a method of selecting ground motions for three-dimensional time history analysis of structures was developed in accordance with the criteria of seismic design code. In the method, the square roots of sum of squares for selected response spectra are very similar to the shape and size of the design spectrum. Also, the algorithm is simple, so takes a few seconds for selecting input ground motions. The proposed method is applicable to all target spectra which has only mean spectrum, such as design spectrum, uniform hazard spectrum or conditional spectrum.

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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    • 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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Retrieving the Time History of Displacement from Measured Acceleration Signal

  • Han, Sangbo
    • Journal of Mechanical Science and Technology
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    • v.17 no.2
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    • pp.197-206
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    • 2003
  • It is intended to retrieve the time history of displacement from measured acceleration signal. In this study, the word retrieving means reconstructing the time history of original displacement signal from already measured acceleration signal not just extracting various information using relevant signal processing techniques. Unlike extracting required information from the signal, there are not many options to apply to retrieve the time history of displacement signal, once the acceleration signal is measured and recorded with given sampling rate. There are two methods, in general, to convert measured acceleration signal into displacement signal. One is directly integrating the acceleration signal in time domain. The other is dividing the Fourier transformed acceleration signal by the scale factor of - $\omega$$^2$and taking the inverse Fourier transform of it. It turned out both the methods produced a significant amount of errors depending on the sampling resolution in time and frequency domain when digitizing the acceleration signals. A simple and effective way to convert the time history of acceleration signal into the time history of displacement signal without significant errors is studied here with the analysis on the errors involved in the conversion process.

Response of Base Isolation System Subjected to Spectrum Matched Input Ground Motions (스펙트럼 적합 입력지반운동에 의한 면진구조의 응답 특성)

  • Kim, Jung Han;Kim, Min Kyu;Choi, In-Kil
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.2
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    • pp.89-95
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    • 2013
  • Structures in a nuclear power system are designed to be elastic even under an earthquake excitation. However a structural component such as an isolator shows inelastic behavior inherently. For the seismic assessment of nonlinear structures, response history analysis should be performed. In this study, the response of base isolation system was analyzed by response history analysis for the seismic performance assessment. Firstly, several seismic assessment criteria for a nuclear power plant structure were reviewed for the nonlinear response history analysis. Based on these criteria, the spectrum matched ground motion generation method modifying a seed earthquake ground motion time history was adjusted. Using these spectrum matched accelerograms, the distribution of displacement responses of the simplified base isolation system was evaluated. The resulting seismic responses excited by the modified ground motion time histories and the synthesized time history generated by stochastic approach were compared. And the response analysis of the base isolation system considering the different intensities in each orthogonal direction was performed.

Computing input energy response of MDOF systems to actual ground motions based on modal contributions

  • Ucar, Taner
    • Earthquakes and Structures
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    • v.18 no.2
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    • pp.263-273
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    • 2020
  • The use of energy concepts in seismic analysis and design of structures requires the understanding of the input energy response of multi-degree-of-freedom (MDOF) systems subjected to strong ground motions. For design purposes and non-time consuming analysis, however, it would be beneficial to associate the input energy response of MDOF systems with those of single-degree-of-freedom (SDOF) systems. In this paper, the theoretical formulation of energy input to MDOF systems is developed on the basis that only a particular portion of the total mass distributed among floor levels is effective in the nth-mode response. The input energy response histories of several reinforced concrete frames subjected to a set of eleven horizontal acceleration histories selected from actual recorded events and scaled in time domain are obtained. The contribution of the fundamental mode to the total input energy response of MDOF frames is demonstrated both graphically and numerically. The input energy of the fundamental mode is found to be a good indicator of the total energy input to two-dimensional regular MDOF structures. The numerical results computed by the proposed formulation are verified with relative input energy time histories directly computed from linear time history analysis. Finally, the elastic input energies are compared with those computed from time history analysis of nonlinear MDOF systems.