• Title, Summary, Keyword: spectral displacement

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Further seismic displacement PSDF results

  • Morales, C.A.
    • Structural Engineering and Mechanics
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    • v.34 no.5
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    • pp.663-666
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    • 2010
  • The spectral content of ground displacement of the 10 largest last California earthquakes is studied. Specifically, the power spectral density function of the critical horizontal-component record of the closest-to-epicenter station is analyzed in each case. The results permit to state that horizontal ground displacement is a narrow-band process. This fact was previously noticed while trying to solve the large-base-displacement problem in isolated structures and it was fundamental in the solution of this issue; however, these preliminary results were limited in number to enable a statement like the foregoing one. Thus, the broader results presented herein were necessary.

Probabilistic analysis of spectral displacement by NSA and NDA

  • Devandiran, P.;Kamatchi, P.;Rao, K. Balaji;Ravisankar, K.;Iyer, Nagesh R.
    • Earthquakes and Structures
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    • v.5 no.4
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    • pp.439-459
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    • 2013
  • Main objective of the present study is to determine the statistical properties and suitable probability distribution functions of spectral displacements from nonlinear static and nonlinear dynamic analysis within the frame work of Monte Carlo simulation for typical low rise and high rise RC framed buildings located in zone III and zone V and designed as per Indian seismic codes. Probabilistic analysis of spectral displacement is useful for strength assessment and loss estimation. To the author's knowledge, no study is reported in literature on comparison of spectral displacement including the uncertainties in capacity and demand in Indian context. In the present study, uncertainties in capacity of the building is modeled by choosing cross sectional dimensions of beams and columns, density and compressive strength of concrete, yield strength and elastic modulus of steel and, live load as random variables. Uncertainty in demand is modeled by choosing peak ground acceleration (PGA) as a random variable. Nonlinear static analysis (NSA) and nonlinear dynamic analysis (NDA) are carried out for typical low rise and high rise reinforced concrete framed buildings using IDARC 2D computer program with the random sample input parameters. Statistical properties are obtained for spectral displacements corresponding to performance point from NSA and maximum absolute roof displacement from NDA and suitable probability distribution functions viz., normal, Weibull, lognormal are examined for goodness-of-fit. From the hypothesis test for goodness-of-fit, lognormal function is found to be suitable to represent the statistical variation of spectral displacement obtained from NSA and NDA.

Spectral Element Analysis of the Pipeline Conveying Internal Unsteady Fluid (내부 비정상 유동을 갖는 파이프계의 스펙트럼요소해석)

  • Park, Jong-Hwan;Lee, U-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.12
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    • pp.1574-1585
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    • 2005
  • In this paper, a spectral element model is developed for the uniform straight pipelines conveying internal unsteady fluid. Four coupled pipe-dynamics equations are derived first by using the Hamilton's principle and the principles of fluid mechanics. The transverse displacement, the axial displacement, the fluid pressure and the fluid velocity are all considered as the dependent variables. The coupled pipe-dynamics equations are then linearized about the steady state values of the fluid pressure and velocity. As the final step, the spectral element model represented by the exact dynamic stiffness matrix, which is often called spectral element matrix, is formulated by using the frequency-domain solutions of the linearized pipe-dynamics equations. The FFT-based spectral dynamic analyses are conducted to evaluate the accuracy of the present spectral element model and also to investigate the structural dynamic characteristics and the internal fluid transients of an example pipeline system.

Residual displacement estimation of simple structures considering soil structure interaction

  • Aydemir, Muberra Eser;Aydemir, Cem
    • Earthquakes and Structures
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    • v.16 no.1
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    • pp.69-82
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    • 2019
  • As the residual displacement and/or drift demands are commonly used for seismic assessment of buildings, the estimation of these values play a very critical role through earthquake design philosophy. The residual displacement estimation of fixed base structures has been the topic of numerous researches up to now, but the effect of soil flexibility is almost always omitted. In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions for both fixed and interacting cases. The elastoplastic model is used to represent non-degrading structures. Based on time history analyses, a new simple yet effective equation is proposed for residual displacement demand of any system whether fixed base or interacting as a function of structural period, lateral strength ratio and spectral displacement.

Spectral Element Modeling of an Extended Timoshenko Beam Based on the Force-Displacement Relations (힘-변위 관계를 이용한 확장된 티모센코 보에 대한 스펙트럴 요소 모델링)

  • Lee, Chang-Ho;Lee, U-Sik
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.45-48
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    • 2008
  • Periodic lattice structures such as the large space lattice structures and carbon nanotubes may take the extension-transverse shear-bending coupled vibrations, which can be well represented by the extended Timoshenko beam theory. In this paper, the spectrally formulated finite element model (simply, spectral element model) has been developed for extended Timoshenko beams and applied to some typical periodic lattice structures such as the armchair carbon nanotube, the periodic plane truss, and the periodic space lattice beam.

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A Worldview-2 satellite imagery pansharpening algorithm for minimizing the effects of local displacement (지역적 변위에 따른 영향을 최소화하기 위한 Worldview-2 위성영상의 융합 기법)

  • Choi, Jae-Wan
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.6
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    • pp.577-582
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    • 2011
  • In remote sensing, spatial/spectral distortions are recognized as two of the main problems in the pansharpening algorithm. Most pansharpening methodologies show a tendency to distort spatial information from objects such as buildings and vehicles because there are local spatial dissimilarities among multispectral bands in Worldview-2 satellite imagery. In this paper, we propose a new pansharpening algorithm in order to minimize the effects of the local displacement of spatial information in the pansharpening process. In experiments using Worldview-2 images, our method provided better spectral and spatial quality than pre-existing pansharpening methods.

A displacement-based seismic design method with damage control for RC buildings

  • Ayala, A. Gustavo;Castellanos, Hugo;Lopez, Saul
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.413-434
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    • 2012
  • This paper presents a displacement-based seismic design method with damage control, in which the targets for the considered performance level are set as displacements and a damage distribution is proposed by the designer. The method is based on concepts of basic structural dynamics and of a reference single degree of freedom system associated to the fundamental mode with a bilinear behaviour. Based on the characteristics of this behaviour curve and on the requirements of modal spectral analysis, the stiffness and strength of the structural elements of the structure satisfying the target design displacement are calculated. The formulation of this method is presented together with the formulations of two other existing methods currently considered of practical interest. To illustrate the application of the proposed method, 5 reinforced concrete plane frames: 8, 17 and 25 storey regular, and 8 and 12 storey irregular in elevation. All frames are designed for a seismic demand defined by single earthquake record in order to compare the performances and damage distributions used as design targets with the corresponding results of the nonlinear step by step analyses of the designed structures subjected to the same seismic demand. The performances and damage distributions calculated with these analyses show a good agreement with those postulated as targets.

A displacement-based seismic design procedure for buildings with fluid viscous dampers

  • Banuelos-Garcia, Francisco H.;Ayala, Gustavo;Lopez, Saul
    • Earthquakes and Structures
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    • v.18 no.5
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    • pp.609-623
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    • 2020
  • This paper presents a displacement-based seismic design procedure for new structures with fluid viscous dampers and/or for existing structures, where these devices are required as a retrofit measure and damage control. To consider the non-proportional damping produced by these devices in a conventional modal spectral analysis, the effect of the fluid viscous dampers is approximated as the sum of a proportional damping matrix and a complementary matrix which is representative of non-proportional damping matrix. To illustrate the application of this procedure and evaluate the performance of structures designed with the procedure proposed, five regular plane frames: 8, 12, 17, 20 and 25-storey, and an 8-storey building are designed. The seismic demands used for design and validation were the records obtained at the SCT site during the 1985 Michoacan earthquake, and that of the 2017 Morelos - Puebla earthquake obtained at the Culhuacan site, both stations located on soft soil sites. To validate the procedure proposed, the performances and damage distributions used as design targets were compared with the corresponding results from the nonlinear step-by-step analyses of the designed structures subjected to the same seismic demands.

The topographic effect of ground motion based on Spectral Element Method

  • Liu, Xinrong;Jin, Meihai;Li, Dongliang;Hu, Yuanxin;Song, Jianxue
    • Geomechanics and Engineering
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    • v.13 no.3
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    • pp.411-429
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    • 2017
  • A Spectral Element Method for 3D seismic wave propagation simulation is derived based on the three-dimensional fluctuating elastic dynamic equation. Considering the 3D real terrain and the attenuation characteristics of the medium, the topographic effect of Wenchuan earthquake is simulated by using the Spectral Element Method (SEM) algorithm and the ASTER DEM model. Results show that the high PGA (peak ground acceleration) region was distributed along the peak and the slope side away from the epicenter in the epicenter area. The overall distribution direction of high PGA and high PGV (peak ground velocity) region is parallel to the direction of the seismogenic fault. In the epicenter of the earthquake, the ground motion is to some extent amplified under the influence of the terrain. The amplification effect of the terrain on PGA is complicated. It does not exactly lead to amplification of PGA at the ridge and the summit or attenuation of PGA in the valley.

Spectral Element Modeling for Rotating Shafts (회전축에 대한 스펙트럴요소 모델링)

  • Lee, Jea-Sang;Yong, Suk-Jin;U-Sik, Lee
    • Proceedings of the KSR Conference
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    • pp.749-754
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    • 2007
  • In this paper, the vibration of a rotating shaft with a thin rigid disk is considered. It is assumed that the shaft has uniform, circular cross-section. Based on the Timoshenko-beam theory, the transverse displacements and slops in two lateral directions, the axial displacement, and the torsional deformation are considered. The spectral element method is used for the vibration analysis of the rotating shaft with a thin rigid disk, which is modeled by two shaft elements and a thin rigid disk element.

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