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Articles 4531 - 4560 of 4581

Full-Text Articles in Engineering

The Influence Of Viscoelastic Damping On The Dynamics — Behavior Of An Embedded Foundation, A. P. S. Selvadurai Apr 1981

The Influence Of Viscoelastic Damping On The Dynamics — Behavior Of An Embedded Foundation, A. P. S. Selvadurai

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The present paper examines the problem of the dynamic behavior of a rigid circular foundation deeply embedded in bonded contact with a viscoelastic soil mass of infinite extent. The viscous phenomena are accounted for by the introduction of a complex shear modulus. By employing a rigorous mathematical analysis of the problem an explicit results is derived for the dynamic axial compliance of the embedded foundation. The numerical results presented in the paper illustrate the manner in which viscous damping influences this compliance.

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Method Of Influence Function And Its Application, Y. S. Wang, K. C. Wang, T. Q. He Apr 1981

Method Of Influence Function And Its Application, Y. S. Wang, K. C. Wang, T. Q. He

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Within the limited space, the authors have aimed to present concisely final forms of influence function of circle center displacement due to either suddenly or harmonically acted vertical load uniformly distributed over circular area on the surface of an elastic half-space, along with formulae of the method of influence function of circle center displacement for determination of the vertical displacements of points outside and inside the bases of circular, ring and rectangular foundations, as well as the average displacement of these bases. The determination of the parameters of the lumped analog for vibration of the rectangular foundations has also been …

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Explosion Codas And Design Seismic Coefficient, S. K. Guha, S. S. Patil, J. G. Padale Apr 1981

Explosion Codas And Design Seismic Coefficient, S. K. Guha, S. S. Patil, J. G. Padale

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In view of construction of structures in seismic zones like high dams, nuclear power plants etc., evaluation of ‘site dependent design seismic coefficient’ has been of paramount importance. It is thus necessary to assess correctly ‘amplification factor’ of ground motion due to surface geology during earthquakes. This ground amplification factor depends on ‘predominant period’ of site in addition to other factors according to Kanai and others. Though micro tremors have been utilized for estimation of predominant period of site, it has been shown that explosion generated codas could also be used to obtain ground amplification factor useful for estimation of …

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Response Of Multiple-Mass Systems To Nonvertically Incident Seismic Waves, J. Bielak, J. A. Coronato Apr 1981

Response Of Multiple-Mass Systems To Nonvertically Incident Seismic Waves, J. Bielak, J. A. Coronato

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A variational procedure is used for calculating the response of two foundations with rectangular bases supported on a viscoelastic halfspace and subjected to horizontally and vertically incident SH-waves and Rayleigh waves. Results which include the response of massless foundations and those with mass indicate that the dynamic behavior of a rigid foundation to traveling wave excitation can be affected significantly by the presence of a neighboring foundation. The effect is most pronounced when the direction of the incoming wave is parallel to the axis of the two masses, in which case a noticeable reduction in the response of the downstream …

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Scale Modelling Of Soil Structure Interaction During Earthquakes Using A Programmed Series Of Explosions During Centrifugation, A. Zelikson, B. Devaure, D. Badel Apr 1981

Scale Modelling Of Soil Structure Interaction During Earthquakes Using A Programmed Series Of Explosions During Centrifugation, A. Zelikson, B. Devaure, D. Badel

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Scale models of Nuclear Power plants were constructed to study soil structure interaction during Earthquakes. The centrifuge of the C.E.S.T.A. Center near Bordeaux, France, was used to simulate gravity at 100 g (length scale 1: 100) on a 1000 kg net weight of soil and structure. The Earthquake was simulated by a surface wave created by a programmed series of small explosions suitably modified so that the free field signals of horizontal and vertical accelerometers had spectra resembling those of real Earthquakes according to similitude laws. The problem of echoes and suitability of a confined structure was studied without models …

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Dynamic Excitation For Geotechnical Centrifuge Modelling, J. A. Cheney Apr 1981

Dynamic Excitation For Geotechnical Centrifuge Modelling, J. A. Cheney

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The method of physical modeling in the centrifuge is growing in acceptance in the U.S.A. following many years of use in U.S.S.R., Denmark, England, Norway, France and Japan. Simulation of dynamic events (machine vibration, wave forces, and earthquake) in modeling in the centrifuge has important applications, especially on the large national Geotechical Centrifuge being constructed at NASA-ARC. The most difficult problem is that of earthquake simulation. Several schemes for light weight shakers have been proposed in a Workshop on Dynamic Excitation for Geotechnical Centrifuge Model Testing held in August, 1979. More recently, a scheme has been presented which utilizes traveling …

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Initial Results From A Stacked Ring Apparatus For Simulation Of A Soil Profile, R. V. Whitman, P. C. Lambe, B. L. Kutter Apr 1981

Initial Results From A Stacked Ring Apparatus For Simulation Of A Soil Profile, R. V. Whitman, P. C. Lambe, B. L. Kutter

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A stack of 48 rings, lined with a latex membrane, is used to confine a column of soil 12 inches high by 12 inches in diameter (300 mm x 300 mm). Both dry and saturated columns of fine sand are shaken at their base, at a centrifugal acceleration of 35.5 g. Measurements of the settlement of the surface, horizontal displacement and pore pressures show that the columns of soil are behaving essentially (although not exactly) as one-dimensional shear beams.

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Scaling Considerations For Dynamic Experiments, R. M. Schmidt Apr 1981

Scaling Considerations For Dynamic Experiments, R. M. Schmidt

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The geotechnical centrifuge has been shown to be a very valuable experimental technique in the investigation of explosive and impact cratering behavior. A brief summary of recent experiments is given along with a pertinent bibliography. These works have served to establish the practicality of performing dynamic experiments on the centrifuge as well as to provide a theoretical basis for their interpretation.

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Offshore Caissons On Porous Saturated Soil, George Gazetas, Emmanuel Petrakis Apr 1981

Offshore Caissons On Porous Saturated Soil, George Gazetas, Emmanuel Petrakis

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

While currently available methods of dynamic soil-foundation interaction idealize the soil as a continuum, this paper presents a general theory to obtain the dynamic response of offshore caissons resting on a saturated or nearly saturated poroelastic medium. The model, based on Biot's theory, considers the compressibility of both solid and fluid phase and assumes that the fluid flow is governed by Darcy's Law for an isotropic medium. Results are presented as plots of normalized amplitudes of displacement load or rotation-moment ratios for a rigid strip founded on a dense coarse sand. The results demonstrate that fluid compressibility, which is primarily …

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Seismic Design Of The San Francisco Ocean Outfall, O. H. Gilbert Jr., Y. Eisenberg, D. D. Treadwell Apr 1981

Seismic Design Of The San Francisco Ocean Outfall, O. H. Gilbert Jr., Y. Eisenberg, D. D. Treadwell

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

San Francisco's Southwest Ocean Outfall will extend four miles into the Pacific Ocean. Offshore, the Outfall will cross the San Andreas Fault zone. Major design concerns for the 12-foot inside diameter reinforced concrete pipe included seismic foundation stability, backfill liquefaction, and rupture by fault displacement. Foundation stability was achieved by selection of adequate embedment depths. A coarse pervious backfill to preclude liquefaction-induced pore water pressure gradients was selected based on analyses with the computer program APOLLO. Special joints were designed within and adjacent to the fault zone to limit damage due to fault rupture and to accommodate deformations away from …

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Exceptional Issues In Offshore Earthquake Geotechnology, R. G. Bea Apr 1981

Exceptional Issues In Offshore Earthquake Geotechnology, R. G. Bea

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This Moderator's Report reviews the state-of-the-art report and papers submitted to the session on Offshore Earthquake Geotechnology. Selection of earthquake intensity and characteristics of ground motions for design of offshore structures, offshore source and attenuation characterizations, local site effects, and structure-foundation-soil interactions that may be exceptional to the offshore environment are discussed.

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Session 6: Discussion And Replies, Multiple Authors Apr 1981

Session 6: Discussion And Replies, Multiple Authors

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Seismic Analysis As A Tool In The Design Of Two Earth Dams, A. Yziquel, M. Lino, G. Post, B. Tardieu Apr 1981

Seismic Analysis As A Tool In The Design Of Two Earth Dams, A. Yziquel, M. Lino, G. Post, B. Tardieu

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Two dynamic analysis studies of embankment dams are described. One dam is 43m high on alluvium, the other is 140m high on a rock foundation in a highly seismic area. The main emphasis is on the practical nature of the analytical methods and their value as design tools. The earthquake design features of both projects are described and the closing paragraphs attempt to draw attention to the main points to be considered when running an earthquake analysis of earth dams.

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Seismic Analysis Of Spinney Mountain Dam, J. V. Williamson, M. E. Shaffer Apr 1981

Seismic Analysis Of Spinney Mountain Dam, J. V. Williamson, M. E. Shaffer

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The Spinney Mountain Dam, now under construction in central Colorado, is a zoned earth embankment with a maximum height of 95 feet above foundation. Detailed geological investigations revealed rejuvenated sediments of nearby older faults, which have undergone tectonic movement within the past 13,000 to 30,000 years and hence are considered capable. Studies indicate the largest earthquake expected on the controlling fault would have a Richter Magnitude of about 6.2, implying peak ground accelerations at the site of about 0.6g and a 15-second duration of strong motion. Displacement on a branch of the main capable fault during such an event is …

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Longitudinal Seismic Behavior Of Earth Dams, A. M. Abdei-Ghaffar Apr 1981

Longitudinal Seismic Behavior Of Earth Dams, A. M. Abdei-Ghaffar

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Earthquake-induced vibration in earth darns in a direction parallel to the darn axis is studied using analytical elastic models. The non-homogeneity of the darn materials is taken into account by assuming specific variations of the elastic moduli along the depth due to the confining pressure. Based on the models, a rational procedure is developed to estimate dynamic stresses and strains (both shear and normal) and corresponding elastic moduli and damping factors for earth darns from their hysteretic responses to real earthquakes, utilizing the hysteresis loops from the crest and base records. This leads to a study of the variation of …

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Effective Stress Analyses Of Seismic Stability, E. Kavazanjian Jr., J. L. Chameau Apr 1981

Effective Stress Analyses Of Seismic Stability, E. Kavazanjian Jr., J. L. Chameau

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The factors involved in performing effective stress analysis of seismic stability problems are examined. The advantages of using a stochastic model for pore pressure generation are discussed. A simplified analysis of a hypothetical case is outlined to illustrate the factors involved in performing effective stress stability analysis.

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Estimation Of Displacements Of Rockfill Dams Due To Seismic Shaking, J. L. Vonthun, C. W. Harris Apr 1981

Estimation Of Displacements Of Rockfill Dams Due To Seismic Shaking, J. L. Vonthun, C. W. Harris

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

A computer code for estimation of displacement of sliding surfaces during dynamic loading is discussed. The procedure allows selective incorporation of the effects of horizontal and vertical inertial forces, excess pore pressure development, hydrodynamic forces, shear strength reduction, and dilation. The relative effect of these parameters on the computed displacements can be readily determined for alternative design layouts or material behavior assumptions.

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Seismic Deformation Of Dams By Correlative Methods, Y. K. Lin, K. V. Rodda, C. W. Perry, D. K. Gill Apr 1981

Seismic Deformation Of Dams By Correlative Methods, Y. K. Lin, K. V. Rodda, C. W. Perry, D. K. Gill

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Analyses are presented of the anticipated earthquake performance of three generally similar earth dams, situated in a seismically active area of northern California. The series of analyses illustrates a cost-effective approach which involved full-scale finite element analyses of one dam, and the use of limited dynamic analysis techniques and correlations to evaluate the other two. The simplified techniques were applied only after testing them against the finite element analyses, information is also presented on how the results of simplified and full-scale dynamic analysis procedures correlate.

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On The Dynamic Stability Of Block Sliding On Rock Slopes, Wang Sijing, Zhan Juming Apr 1981

On The Dynamic Stability Of Block Sliding On Rock Slopes, Wang Sijing, Zhan Juming

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This paper deals with the dynamic analysis of block sliding on rock slope along plane surfaces, such as joints, bedding planes and faults. According to the results obtained in the shaking tests the dynamic friction along a sliding surface is dependent on the velocity of relative motion, and can be determined by using the proposed method of test. On the basis of conducted experiments a differential equation was established. The integration of the dynamics equation by numerical method provides a basis for evaluation of slope stability in terms of critical displacement and dynamic instability.

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On The Use Of Nonlinear Soil Models, Albert T. F. Chen Apr 1981

On The Use Of Nonlinear Soil Models, Albert T. F. Chen

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The basic definitions of, and the differences between, currently available soil models are reviewed. These models are applied to site response analyses where two depths and two levels of base input motion are considered. Computational results are presented and compared with regard to the effects of using different soil models on computed site response. Other implications resulting from the choice of soil model for seismic response analysis are also discussed.

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Permanent Deformation Of Earth Dams Under Earthquakes, William Y. J. Shieh, Rodney J. Huang Apr 1981

Permanent Deformation Of Earth Dams Under Earthquakes, William Y. J. Shieh, Rodney J. Huang

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Assessment of dam embankment deformation by various methods such as those proposed by Newmark, Ambraseys and Seed was reviewed herewith. A simple method based on dynamic response spectrum analyses by step-by-step integration technique is proposed for independent permanent deformation evaluation. The proposed method assumes that failure occurs on a well-defined slip surface and that the material behaves elastically at stress level below failure but develops a perfectly plastic behavior above the yield acceleration. The results of the proposed method were compared with those obtained from other method for actual examples. Favorable agreement on the analytical results was achieved.

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Analysis Of Dynamic Shear Strain Distributed In Three Dimensional Earthdam Models, T. Ohmachi Apr 1981

Analysis Of Dynamic Shear Strain Distributed In Three Dimensional Earthdam Models, T. Ohmachi

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Dynamic shear strain distribution have been evaluated and illustrated for three dimensional earthdam models. The analysis method applied here is a simplified finite element method, which has proved to give vibration modes of an earthdam to a satisfactory level of accuracy by involving a smaller number of degrees of freedom. Mass and stiffness matrices of a dam have been formulated for two types of the shear modulus distribution, one uniform and the other linearly increasing with depth below the crest. Both magnitude and location of the maximum shear strain have been discussed in relation to topography of dam sites.

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A Simplified Procedure For Evaluating Maximum Response Of Soil Layer During An Earthquake, Fu Shengcong, Jiang Jingbei Apr 1981

A Simplified Procedure For Evaluating Maximum Response Of Soil Layer During An Earthquake, Fu Shengcong, Jiang Jingbei

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

In this paper, the horizontally stratified soil layers are simplified as a shearing type multidegree of freedom linear system. The transfer function of the system is determined in accordance with the statistic analysis of the result from the mode superposition method of soil layer earthquake response. By referring to the method of finding the extreme value in probabilistic theory, a response spectrum corresponding to the power spectral density of soil layers is given. At the same time, distributions of maximum response values of acceleration, displacement, shearing strain and shearing stress of the soil layers along the depth are given according …

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Session 7: Discussion And Replies, Multiple Authors Apr 1981

Session 7: Discussion And Replies, Multiple Authors

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

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Source Mechanism And Seismic Effect Of Tangshan Earthquake, Hong-Qi Fang, Xin-Kwan Miao, Shu-Dong Zhao Apr 1981

Source Mechanism And Seismic Effect Of Tangshan Earthquake, Hong-Qi Fang, Xin-Kwan Miao, Shu-Dong Zhao

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

By analyzing the seismic mechanism of the Tangshan earthquake and its pattern of movement through the study of ground deformation and ground strain of the Tangshan earthquake area it is clear that the breeding and occurrence of this event are controlled by a long-term intense active fault zone. By the ground deformation, displacement, tectonic features and seismic effects after the event, this causative fault is known to be composed of a group of NNE trending right turn strike-slip faults and thus we call it the Tangshan active fault zone.

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Observed And Predicted Liquefaction Of A Sand Stratum, A. Jaime, M. P. Romo, L. Montañez Apr 1981

Observed And Predicted Liquefaction Of A Sand Stratum, A. Jaime, M. P. Romo, L. Montañez

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Field observations and preliminary studies had led to the conclusion that the sand stratum liquefied only in a limited area during the March 14, 1979 earthquake. Further field studies revealed the presence of the sand layer throughout the Enmedio Island. This fact raised questions as to whether the sand liquefied or not in the whole area. To clarify this question, a research program which included cyclic triaxial testing and numerical analyses was undertaken. The results of this study show that the sand layer did liquefy through the Island; however, due to differences in stratigraphic characteristics, superficial signs of liquefaction were …

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Local Site Behaviour In The 1976 Friuli Earthquake, M. Basili, V. Gorelli, F. Muzzi Apr 1981

Local Site Behaviour In The 1976 Friuli Earthquake, M. Basili, V. Gorelli, F. Muzzi

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Soon after the main shock of Friuli, Italy, May 6th 1976 earthquake, two strong motion recorders accelerographs were installed in two sites about 650 meters distant one from the other. One instrument was installed on hard outcropping rock, the other at the surface of an alluvial deposit 20+25 meters thick underlain by a sloping bedrock. Among the numerous records obtained three aftershocks of magnitude about 6 and hypocentral distance within 20 Km, are investigated by comparing maximum accelerations, durations, Arias intensity and Husid ratios. A new numerical tool is proposed which consists of a series of plots of the Husid …

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Observations And Analysis On Building Settlement Due To Tangshan Earthquake, Huang Xiling Apr 1981

Observations And Analysis On Building Settlement Due To Tangshan Earthquake, Huang Xiling

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

This paper describes the significant settlement of buildings on saturated soft clay due to Tangshan earthquake. Results of dynamic triaxial tests and analysis of stress in subsoil will be given. The factors which influence the settlement will also be discussed herein.

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Liquefaction Of The Enmedio Island Soil Deposits, A. Jaime, L. Montañez, M. P. Romo Apr 1981

Liquefaction Of The Enmedio Island Soil Deposits, A. Jaime, L. Montañez, M. P. Romo

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

The results of field testing and of simplified liquefaction analyses of the Enmedio Island soil deposits are presented and discussed in this paper. It is found that for this case history simple criteria for assessing liquefaction potential yield results in accord with field behavior.

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Geotechnical And Strong Motion Aspects Of Recent Indian Earthquakes, Jai Krishna Apr 1981

Geotechnical And Strong Motion Aspects Of Recent Indian Earthquakes, Jai Krishna

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

India had many strong earthquakes in the past. The paper describes some strong motion and geotechnical aspects of Indian earthquakes.

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