Seismic response of three-dimensional alluvial deposit with irregularities for incident wave motion from a point source

1995 ◽  
Vol 32 (6) ◽  
pp. A270
Keyword(s):  
Point Source ◽  
Seismic Response ◽  
Incident Wave ◽  
Wave Motion ◽  
Three Dimensional ◽  
Alluvial Deposit

Seismic response of three-dimensional alluvial deposit with irregularities for incident wave motion from a point source

1994 ◽  
Vol 84 (6) ◽  
pp. 1801-1814
Author(s):  
Masahiro Kawano ◽  
Satoshi Matsuda ◽  
Kozo Toyoda ◽  
Jun Yamada
Keyword(s):  
Point Source ◽  
Wave Field ◽  
Incident Wave ◽  
Wave Motion ◽  
Surface Soil ◽  
Soil Layer ◽  
Tangential Component ◽  
Focal Distance ◽  
Alluvial Deposit ◽  
Surface Displacements

Abstract The purpose of this article is to further investigate the influence of local site conditions of surface soil layers on seismic ground motion by studying the response of a semi-spherical alluvial deposit model under the more realistic type incident wave field. The incident wave field is a spherical wave radiated from a point source that is situated at the near focal distance and the far focal distance. A plane SH wavelet is also considered for comparison. A least-squares technique is applied to solve the boundary problem. The surface displacements on the alluvial deposit and in the elastic half-space are evaluated for various focal distances and source incidence angles. The numerical results indicate that there are significant differences concerning scattering and diffraction of wave motions between the two horizontal components when the semi-spherical alluvial deposit is subjected to incident wave motions from a point source. In the near field and for the component involving predominantly P and SV waves, the coupling of these waves induces a great variation in the spatial distributions, the amplitudes, and the time histories of the surface displacements compared to the tangential component, which involves mostly SH waves. The wave propagation characteristics of this component are very similar to those for a plane SH wavelet. In the far field and for the tangential component, there is not such strong coupling among waves. It is also shown that the first reflected waves at the curved boundary are deeply related to scattering and to diffraction of wave motion in a surface soil layer with irregularities and play an important role in the development of later arrivals.

Prediction of Ship Motions Via a Three-Dimensional Time-Domain Method Following a Quad-Tree Adaptive Mesh Technique

2020 ◽  
Vol 27 (1) ◽  
pp. 29-38
Author(s):  
Teng Zhang ◽  
Junsheng Ren ◽  
Lu Liu
Keyword(s):  
Free Surface ◽  
Incident Wave ◽  
Time Domain ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Wave Profile ◽  
Time Domain Method ◽  
Ship Motions ◽  
Quad Tree ◽  
Mesh Technique

AbstractA three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude-Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.

Incorporation of spatial variability in modeling non-point source groundwater nitrate pollution

1996 ◽  
Vol 33 (4-5) ◽  
pp. 233-240 ◽  
Author(s):  
F. S. Goderya ◽  
M. F. Dahab ◽  
W. E. Woldt ◽  
I. Bogardi
Keyword(s):  
Spatial Variability ◽  
Point Source ◽  
Three Dimensional ◽  
Nitrate Contamination ◽  
Geostatistical Simulation ◽  
Chemical Measurements ◽  
Spatially Distributed ◽  
Potential Benefits ◽  
Zone Modeling ◽  
Physical And Chemical

A methodology for incorporation of spatial variability in modeling non-point source groundwater nitrate contamination is presented. The methodology combines geostatistical simulation and unsaturated zone modeling for estimating the amount of nitrate loading to groundwater. Three dimensional soil nitrogen variability and 2-dimensional crop yield variability are used in quantifying potential benefits of spatially distributed nitrogen input. This technique, in combination with physical and chemical measurements, is utilized as a means of illustrating how the spatial statistical properties of nitrate leaching can be obtained for different scenarios of fixed and variable rate nitrogen applications.

Effect of Pile-Soil-Structure Interaction on the Cable-Stayed Bridge in Response to the Earthquake

2014 ◽  
Vol 539 ◽  
pp. 731-735 ◽  
Author(s):  
Yu Chen
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Cable Stayed Bridge ◽  
Three Dimensional Finite Element

In this thesis, based on the design of a 140+90m span unusual single tower and single cable plane cable-stayed bridge, free vibration characteristics and seismic response are investigated; three dimensional finite element models of a single tower cable-stayed bridge with and without the pile-soil-structure interaction are established respectively by utilizing finite element software MIDAS/CIVIL, seismic response of Response spectrum and Earthquake schedule are analyzed respectively and compared. By the comparison of the data analysis, for small stiffness span cable-stayed bridge, the pile-soil-structure interaction can not be ignored with calculation and analysis of seismic response.

Dynamics of a composite system in a point source-induced space–time

2021 ◽  
pp. 2150144
Author(s):  
Abdullah Guvendi
Keyword(s):  
Point Source ◽  
Composite System ◽  
Dimensional Space ◽  
Energy Levels ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Space Time ◽  
Spin Coupling ◽  
Quantum Oscillator ◽  
Dimensional Space Time

We investigate the dynamics of a composite system ([Formula: see text]) consisting of an interacting fermion–antifermion pair in the three-dimensional space–time background generated by a static point source. By considering the interaction between the particles as Dirac oscillator coupling, we analyze the effects of space–time topology on the energy of such a [Formula: see text]. To achieve this, we solve the corresponding form of a two-body Dirac equation (fully-covariant) by assuming the center-of-mass of the particles is at rest and locates at the origin of the spatial geometry. Under this assumption, we arrive at a nonperturbative energy spectrum for the system in question. This spectrum includes spin coupling and depends on the angular deficit parameter [Formula: see text] of the geometric background. This provides a suitable basis to determine the effects of the geometric background on the energy of the [Formula: see text] under consideration. Our results show that such a [Formula: see text] behaves like a single quantum oscillator. Then, we analyze the alterations in the energy levels and discuss the limits of the obtained results. We show that the effects of the geometric background on each energy level are not same and there can be degeneracy in the energy levels for small values of the [Formula: see text].

scholarly journals Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Chen Xia ◽  
Chengzhi Qi ◽  
Xiaozhao Li
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Time Domain ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Seismic Loads ◽  
Element Analysis ◽  
Artificial Boundaries ◽  
The Time Domain ◽  
Transmitting Boundaries

Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil.

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