Coupled Rocking and Translating Vibrations of a Buried Foundation

1974 ◽  
Vol 41 (3) ◽  
pp. 697-702 ◽  
Author(s):  
S. A. Thau ◽  
A. Umek
Keyword(s):  
Equations Of Motion ◽  
Surrounding Medium ◽  
Early Time ◽  
Free Vibrations ◽  
Elastic Half Space ◽  
P Wave ◽  
Initial Time ◽  
Transient Time ◽  
Coupled Equations ◽  
Time Period

The plane strain model of a rigid building foundation embedded below the surface of an elastic half space is treated. The foundation is assumed to be vibrating freely with arbitrary transient time-dependences U(t) and V(t) in the horizontal and vertical directions, respectively, and to be rocking about its mass center with magnitude Ω(t). The total restraining reactions exerted upon the foundation by the surrounding medium are determined exactly during the initial time period for a P-wave to traverse the foundation base width. Thereafter the results become approximate. In this manner the coupled equations of motion for free vibrations of the foundation are obtained. A numerical example presents the impulse response matrix for U, V, and Ω. Peak responses are found to occur during the early time period where the results are exact.

scholarly journals Dynamic Response of a Circular Tunnel in an Elastic Half Space

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
İrfan Coşkun ◽  
Demirhan Dolmaseven
Keyword(s):  
Boundary Conditions ◽  
Half Space ◽  
Dynamic Pressure ◽  
Equations Of Motion ◽  
Surrounding Medium ◽  
Elastic Half Space ◽  
Polar Coordinates ◽  
Wave Number ◽  
Circular Tunnel ◽  
Tunnel Wall

The vibration of a circular tunnel in an elastic half space subjected to uniformly distributed dynamic pressure at the inner boundary is studied in this paper. For comparison purposes, two different ground materials (soft and hard soil) are considered for the half space. Under the assumption of plane strain, the equations of motion for the tunnel and the surrounding medium are reduced to two wave equations in polar coordinates using Helmholtz potentials. The method of wave expansion is used to construct the displacement fields in terms of displacement potentials. The boundary conditions associated with the problem are satisfied exactly at the inner surface of the tunnel and at the interface between the tunnel and surrounding medium, and they are satisfied approximately at the free surface of the half space. A least-squares technique is used for satisfying the stress-free boundary conditions at the half space. It is shown by comparison that the stresses and displacements are significantly influenced by the properties of the surrounding soil, wave number (i.e., the frequency), depth of embedment, and thickness of the tunnel wall.

Transient Response of a Buried Foundation to Antiplane Shear Waves

1973 ◽  
Vol 40 (4) ◽  
pp. 1061-1066 ◽  
Author(s):  
S. A. Thau ◽  
A. Umek
Keyword(s):  
Equation Of Motion ◽  
Elastic Half Space ◽  
Antiplane Shear ◽  
Initial Time ◽  
Earthquake Response ◽  
Sh Wave ◽  
Time Period ◽  
Long Time ◽  
Base Width ◽  
Rectangular Foundation

A rigid rectangular foundation, embedded at an arbitrary depth below the surface of an elastic half space is subjected to a plane, transient SH-wave. The Laplace and Kantorovich-Lebedev transforms are applied to derive the equation of motion for the foundation during the initial time period required for an SH-wave to traverse the base width. The peak impulse response is found to occur during this time and the response there-after appears to be valid based on a comparison with the known, long-time limit. Consequently, the results presented here can be convolved with an earthquake accelerogram to yield an accurate foundation earthquake response.

Survival With Respect to Morphology in Pulmonary Atresia and Intact Ventricular Septum in Sweden

2021 ◽  
Vol 12 (1) ◽  
pp. 27-34
Author(s):  
Stina Manhem ◽  
Katarina Hanséus ◽  
Håkan Berggren ◽  
Britt-Marie Ekman-Joelsson
Keyword(s):  
Pulmonary Atresia ◽  
Early Time ◽  
Ventricular Septum ◽  
Intact Ventricular Septum ◽  
Early Group ◽  
Time Period ◽  
Medical Reports ◽  
One Year ◽  
Survival Risk ◽  
Late Group

Background: Patients born with pulmonary atresia and intact ventricular septum represent a challenge to pediatric cardiologists. Our objective was to study changes in survival with respect to morphology in all children born with pulmonary atresia and intact ventricular septum in Sweden during 36 years. Methods: A retrospective, descriptive study based on medical reports and echocardiographic examinations consisting of those born between 1980 and 1998 (early group) and those born between 1999 and 2016 (late group). Results: The cohort consists of 171 patients (early group, n = 86 and late group, n = 85) yielding an incidence of 4.35 and 4.46 per 100,000 live births, respectively. One-year survival in the early group was 76% compared to 92% in the late group ( P = .0004). For patients with membranous atresia, one-year survival increased from 78% to 98%, and for muscular pulmonary atresia, from 68% to 85%. In patients with muscular pulmonary atresia and ventriculocoronary arterial communications, there was no significant increase in survival. Risk factors for death were being born in the early time period hazard ratio (HR), 6; 95% CI (2.33-14.28) P = .0002, low birth weight HR, 1.26; 95% CI (1.14-1.4) P < .0001 and having muscular pulmonary atresia HR, 3.74; 95% CI (1.71-8.19) P = .0010. Conclusion: The incidence of pulmonary atresia and intact ventricular septum remained unchanged during the study period. Survival has improved, especially for patients with membranous pulmonary atresia, while being born with muscular pulmonary atresia is still a risk factor for death. To further improve survival, greater focus on patients with muscular pulmonary atresia and ventriculocoronary arterial communications is required.

Free vibration analysis and post-critical free vibrations of nanocomposite rotating beams reinforced with graphene platelet

2021 ◽  
pp. 107754632110511
Author(s):  
Arameh Eyvazian ◽  
Chunwei Zhang ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohammad Alkhedher
Keyword(s):  
Natural Frequency ◽  
Thermal Environment ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Free Vibration Analysis ◽  
Beam Theory ◽  
Weight Fraction ◽  
Free Vibrations ◽  
Graphene Platelet ◽  
The Impact

Treatment of the first natural frequency of a rotating nanocomposite beam reinforced with graphene platelet is discussed here. In regard of the Timoshenko beam theory hypothesis, the motion equations are acquired. The effective elasticity modulus of the rotating nanocomposite beam is specified resorting to the Halpin–Tsai micro mechanical model. The Ritz technique is utilized for the sake of discretization of the nonlinear equations of motion. The first natural frequency of the rotating nanocomposite beam prior to the buckling instability and the associated post-critical natural frequency is computed by means of a powerful iteration scheme in reliance on the Newton–Raphson method alongside the iteration strategy. The impact of adding the graphene platelet to a rotating isotropic beam in thermal ambient is discussed in detail. The impression of support conditions, and the weight fraction and the dispersion type of the graphene platelet on the acquired outcomes are studied. It is elucidated that when a beam has not undergone a temperature increment, by reinforcing the beam with graphene platelet, the natural frequency is enhanced. However, when the beam is in a thermal environment, at low-to-medium range of rotational velocity, adding the graphene platelet diminishes the first natural frequency of a rotating O-GPL nanocomposite beam. Depending on the temperature, the post-critical natural frequency of a rotating X-GPL nanocomposite beam may be enhanced or reduced by the growth of the graphene platelet weight fraction.

scholarly journals IBEM Simulation of Seismic Wave Scattering by a 3D Tunnel Mountain

2021 ◽  
Vol 2021 ◽  
pp. 1-23
Author(s):  
Ping-Lin Jiang ◽  
Hua Jiang ◽  
Yu-Sheng Jiang ◽  
Dai Wang ◽  
Nan Li ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Seismic Wave ◽  
Wave Scattering ◽  
Surface Displacement ◽  
Elastic Half Space ◽  
P Wave ◽  
Severe Damage ◽  
Surface Displacements ◽  
Seismic Wave Scattering ◽  
The One

The seismic wave scattering by a 3D tunnel mountain is investigated by the indirect boundary element method (IBEM). Without loss of generality, the 3D physical model of hemispherical tunnel mountain in an elastic half-space is established, and the influence of the incidence frequency and angle of P or SV wave on the mountain surface displacements is mainly examined. It is shown that there exists quite a difference between the spatial distribution of displacement amplitude under the incident P wave and the one under SV wave and that the incidence frequency and angle of wave, especially the existence of tunnel excavated in the mountain, have a great effect on the surface displacements of mountain; the presence of the tunnel in the mountain may cause the greater amplification of surface displacement, which is unfavorable to the mountain projects. In addition, it should be noted that the tunnel may suffer the more severe damage under the incident SV wave.

scholarly journals Uridylate trapping, induction of UTP deficiency, and stimulation of pyrimidine synthesis de novo by d-galactosone

1982 ◽  
Vol 206 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Dietrich O. R. Keppler ◽  
Christa Schulz-Holstege ◽  
Joachim Fauler ◽  
Karl A. Reiffen ◽  
Friedhelm Schneider
Keyword(s):  
Rat Liver ◽  
De Novo ◽  
Combined Treatment ◽  
Hepatoma Cells ◽  
Nucleotide Metabolism ◽  
Phosphate Deficiency ◽  
Initial Time ◽  
Pyrimidine Synthesis ◽  
Pyrimidine Nucleotide ◽  
Time Period

d-Galactosone (d-lyxo-2-hexosulose) is phosphorylated and metabolized to the uridine diphosphate derivative in AS-30D hepatoma cells and rat liver. These reactions were catalysed in vitro by galactokinase and hexose-1-phosphate uridylyltransferase. Nucleotide analyses by high-performance liquid chromatography and enzymic assays revealed that this galactose analogue interferes with cellular pyrimidine nucleotide metabolism leading to a deficiency of UTP. [14C]Uridine labelling of hepatoma cells indicated a division of [14C]uridylate from UTP into UDP-galactosone; the latter was formed at a rate of more than 1.7mmol×h−1×(kg AS-30D or liver wet wt.)−1. As a consequence of UTP deficiency, d-galactosone (1mmol/1 or 1mmol/kg body wt.) strongly enhanced the rate of pyrimidine synthesis de novo as evidenced by incorporation of 14CO2 into uridylate and by an expansion of the uridylate pool. This resulted in a doubling of the total acid-soluble uridylate pool within 70min in the hepatoma cells and within 110min in rat liver. Combined treatment of hepatoma cells with d-galactosone and N-(phosphonoacetyl)-l-aspartate, an inhibitor of aspartate carbamoyltransferase, prevented the expansion of the uridylate pool and led to a synergistic reduction of UTP to 10% of the content in control cells. Hepatic UTP deficiency was selective with respect to other nucleotide 5′-triphosphates but was associated with reduced contents of UDP-glucose, UDP-glucuronate, and UDP-N-acetylhexosamines. Isolation of the UDP derivative of d-galactosone revealed an extremely alkali-labile UDP-sugar, probably an isomerization product of UDP-galactosone, that was degraded by elimination of UDP with a half-life of 45min at pH7.5 and 37°C. The instability of UDP-galactosone may contribute in vivo to limit the time period of severe uridine phosphate deficiency in addition to the compensatory role of pyrimidine synthesis de novo. During the initial time period, however, d-galactosone is effective as a powerful uridylate-trapping sugar analogue.

Induced versus natural earthquakes: Search for a seismic discriminant

1980 ◽  
Vol 70 (1) ◽  
pp. 269-281
Author(s):  
William A. Peppin ◽  
Charles G. Bufe
Keyword(s):  
Active Faults ◽  
P Wave ◽  
S Wave ◽  
Spectral Parameters ◽  
San Andreas ◽  
Time Period ◽  
Seismic Stress ◽  
Stress Drops ◽  
Natural Earthquakes ◽  
Steam Production

abstract A sizeable body (150 records) of three-component, wideband (0.2 to 50 Hz) digital seismic data has allowed a direct comparison between earthquakes at The Geysers geothermal area, California and along nearby active faults of the San Andreas system. An attempt has been made to find analog or spectral parameters which would permit discrimination between 12 events within the steam production field and 30 outside it. Results of the study for both classes of events are: (1) seismic moments vary with local magnitude ML as log M0 = (1.06 ± 0.11) ML + 16.9 ± 0.1; (2) the ratio of vertical P-wave to horizontal S-wave spectral corner frequencies is near unity; (3) seismic stress drops are low (1.0 to 10 bars); and (4) focal mechanisms are quite comparable during the time period of this study.

Measurement of acoustic properties of near‐surface soils using an ultrasonic waveguide

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 460-465 ◽  
Author(s):  
Rob Long ◽  
Thomas Vogt ◽  
Mike Lowe ◽  
Peter Cawley
Keyword(s):  
Urban Areas ◽  
Surrounding Medium ◽  
Longitudinal Mode ◽  
Acoustic Properties ◽  
P Wave ◽  
S Wave ◽  
Surface Soils ◽  
Near Surface ◽  
Experimental Laboratory ◽  
Ultrasonic Waveguide

A technique is presented that uses a circular ultrasonic waveguide to measure the bulk shear (S‐wave) and longitudinal (P‐wave) velocities of unconsolidated media, with particular application to near‐surface soils. The technique requires measuring the attenuation characteristics of the fundamental longitudinal mode that propagates along an embedded bar, from which the acoustic properties of the surrounding medium are inferred. The principles behind the technique are discussed, and the results of an experimental laboratory validation are presented, followed by details of in‐situ soil property measurements obtained at various sites in urban areas of the United Kingdom.

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