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Articles 12421 - 12450 of 13029

Full-Text Articles in Engineering

Offshore Earthquake Geotechnology — Second Part, P. B. Selnes Apr 1981

Offshore Earthquake Geotechnology — Second Part, P. B. Selnes

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

This second part of the paper discusses submarine slides and acoustic waves from earthquakes, and gives a general overview of aseismic design procedures. Problems which are specific or especially important for the offshore environment are pointed out and discussed in more detail.

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Seismic Pressure Distribution On Retaining Wall With Reinforced Earth Backfill, Swami Saran, D. V. Talwar Apr 1981

Seismic Pressure Distribution On Retaining Wall With Reinforced Earth Backfill, Swami Saran, D. V. Talwar

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

An analysis for determination of lateral thrust on a rigid retaining wall with reinforced earth backfill under seismic condition is described in this paper. The backfill is reinforced with horizontally laid unattached strips and an equivalent horizontal static force replaces the dynamic force. A Coulomb wedge is assumed to develop at limiting equilibrium. Analysis indicates substantial reduction in pressures on the wall due to reinforcement. An optimum length of reinforcing strips of 60 percent of height of wall is indicated.

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A Simple Method Of Estimating Seismic Pressures From Cohesive Soils Against Basement Walls, P. W. Taylor, Z. Lndrawan Apr 1981

A Simple Method Of Estimating Seismic Pressures From Cohesive Soils Against Basement Walls, P. W. Taylor, Z. Lndrawan

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

Although this problem arises frequently in design practice, there is little guidance for the designer in current literature. The proposed method entails estimating the free-field soil deformation caused by a horizontal acceleration. Dynamic increase in earth pressure against an (effectively rigid) wall is assumed to be proportional to the free-field deformation, relative to the base of the wall, with an upper limit equal to full passive pressure. Dynamic pressures calculated using this method are compared with field evidence from published records of observations made on a building in Yokohama during an earthquake.

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A Simplified Elastic Model For Seismic Analysis Of Earth-Retaining Structures With Limited Displacements, A. Arias, F. J. Sanchez-Sesma, E. Ovando-Shelley Apr 1981

A Simplified Elastic Model For Seismic Analysis Of Earth-Retaining Structures With Limited Displacements, A. Arias, F. J. Sanchez-Sesma, E. Ovando-Shelley

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

A simplified elastic model for analyzing static and dynamic interaction between earth-retaining structures and backfill within the range of small displacements is presented. The postulated model covers some of the available models as special cases. The model lends itself readily to the treatment of non-homogeneous backfills with elastic properties varying with depth. Internal (linear) damping in the backfill can be included without impairing the simplicity of the model. Radiation losses due to waves propagating horizontally in fills of semi-infinite extent are inherent to the postulated model. The solutions for some statical and dynamical problems of practical importance show satisfactory agreement …

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Seismic Response Of Retaining Structures, P. M. Byrne, F. Salgado Apr 1981

Seismic Response Of Retaining Structures, P. M. Byrne, F. Salgado

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

A simple method of analysis which allows both the earthquake induced forces and displacements of retaining structures to be computed are presented. The method considers both the weight of the wall and the flexibility and strength of both the backfill and foundation soil. A single degree of freedom elastic-plastic model is used and the equation of motion is integrated to yield the time histories of wall force and displacement. The method is applied to a gravity retaining wall structure subjected to three different acceleration time histories. The results indicate that: (1) the dynamic displacements will be small for walls having …

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Session 3: Discussion And Replies, Multiple Authors Apr 1981

Session 3: Discussion And Replies, Multiple Authors

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

No abstract provided.

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Soil-Pile Interaction Parameters In Vertical And Torsional Vibrations, N. R. Krishnaswamy, B. K. Sharas Chandra, Aftab A. Salam, R. Daniel Apr 1981

Soil-Pile Interaction Parameters In Vertical And Torsional Vibrations, N. R. Krishnaswamy, B. K. Sharas Chandra, Aftab A. Salam, R. Daniel

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

In this paper, two lumped parameter analogues with the inclusion of constant friction damping are suggested to explain the dynamic behavior of pile supported footings during vertical as well as torsional modes of vibrations. Simple theoretical procedures have been described by which the constant frictional force and the constant frictional moment of the friction damping can be evaluated during vertical and torsional vibrations respectively. The suggested procedures into consideration the relevant physical characteristics of the interface between the pile and the soil, as also the length to diameter (L/d) ratio of the pile. Field vibratory teats have been carried out …

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Pavement Soil Interaction Under Dynamic Loads, Bhagirath Lall, Rajendra Puri, J. K. Juneja Apr 1981

Pavement Soil Interaction Under Dynamic Loads, Bhagirath Lall, Rajendra Puri, J. K. Juneja

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

Different types of model pavements were subjected to forced vertical vibration with a view to studying the attenuation properties of Rayleigh Waves. The effect of the road base materials is studied along with the effect of the change in the thickness of the wearing course. The effect of different corner angles at the edge of the road is also investigated. The characteristics of geometric and material damping are discussed in relation to transmission and attenuation of vibration.

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Isolation Of Machine Foundations By Barriers, A. Sridharan, M. V. Nagendra, T. Parthasarathy Apr 1981

Isolation Of Machine Foundations By Barriers, A. Sridharan, M. V. Nagendra, T. Parthasarathy

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

Experimental investigation has been carried out to study the effects due to isolation of foundations subjected to vertical vibration on the displacement amplitude. Tests were conducted on an embedded footing of contact area 45 x 45cm. with different embedments and some on the surface of natural ground. Three isolation barriers viz. air gap, saw dust and sand of various depths were used. From the results of the investigation it was found that an open trench (air gap) around the foundation reduces the displacement amplitude around the footing considerably to an extent of about 75%. Saw dust as a barrier, although …

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Load Settlement Characteristics And Bearing Capacity Of Clays Under Transient Load, B. M. Basavanna, Shamsher Prakash, A. S. Araya Apr 1981

Load Settlement Characteristics And Bearing Capacity Of Clays Under Transient Load, B. M. Basavanna, Shamsher Prakash, A. S. Araya

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

The investigation presented here utilizes finite element technique coupled with Galerikins weighted residual process to predict the settlement of footing resting on the surface of clays and subjected to transient load. The predicted quantities have been compared with the experimental observations of model footing tests. The influence of fundamental natural period of soil and foundation system on the settlement and bearing capacity of footing has been brought out.

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Dynamic Analysis Of Buried Structures, G. D. Manolis, D. E. Beskos Apr 1981

Dynamic Analysis Of Buried Structures, G. D. Manolis, D. E. Beskos

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

The transient response of a circular cylindrical cavity in a linear elastic or viscoelastic infinite or semi-infinite medium under conditions of plane strain is examined. The method employed is the dynamic Boundary Integral Equation Method in conjunction with the Laplace Transform. The results obtained are compared with results stemming from analytical solutions, where available, and numerical solutions to assess the accuracy, efficiency and applicability of the method.

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Dynamic Plasticity In Pile-Soil Interaction Problems, Somnath Bandyopadhyay, Yudhbir Madhav, Madhira R. Madhav Apr 1981

Dynamic Plasticity In Pile-Soil Interaction Problems, Somnath Bandyopadhyay, Yudhbir Madhav, Madhira R. Madhav

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

The dynamic soil-pile interaction problem is solved by the method of characteristics. The nonlinear, non-homogeneous problem was idealized as a piecewise linear problem. The numerical instability of semi-infinite soil column model has been reported, and a stable model, wherein the soil column below, the pile tip is replaced by a single spring and dashpot, has also been presented. The results obtained from the method of characteristics have been compared with those obtained by explicit finite difference scheme. The convergence and stability were studied numerically.

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Seismic Response Of Structures On Soft Foundations, P. M. Byrne Apr 1981

Seismic Response Of Structures On Soft Foundations, P. M. Byrne

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

A method of analysis for predicting the earthquake induced response a structure on a flexible foundation soil is presented. The foundation soil is represented by a bed of elasticplastic springs allowing both the strength of the soil and its stiffness to be incorporated in the analysis. Application of the method indicates: (1) the vertical component of the earthquake has a negligible effect on the response of the structure (2) the maximum induced overturning moment depends primarily on the strength of the soil and whether the foundation is free to lift from the soil (3) overturning of tall buildings is unlikely …

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Ribbed Mat Foundation For Aseismic Building, Agustin A. Mazzeo Apr 1981

Ribbed Mat Foundation For Aseismic Building, Agustin A. Mazzeo

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

This paper describes the design of a two-way ribbed mat used as the foundation of a tall aseismic building located in a very heavy seismic area of northern Venezuela. The soil description, the structural analysis and some construction provisions are also described.

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Damping In Torsional Vibrations Of Embedded Footings, K. S. Sankaran, N. R. Krishnaswamy, P. G. B. Nair Apr 1981

Damping In Torsional Vibrations Of Embedded Footings, K. S. Sankaran, N. R. Krishnaswamy, P. G. B. Nair

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

The existing theoretical models to explain the dynamic behavior of embedded footings, overestimate the real response by neglecting damping forces which are inevitable as a result of slip at the interface of the embedded footing and soil. Many researchers in the field of Soil Dynamics have suggested that the inclusion of friction damping and internal damping in the mathematical model is necessary to improve the reliability of theoretical predictions. In this paper, results of the experimental investigations on full scale model embedded footings subjected to torsional mode of vibration have been presented. The results have been analyzed making use of …

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Soil-Pile Interaction In Liquefiable Cohesionless Soils During Earthquake Loading, Hudson Matlock, Geoffrey R. Martin, Ignatius P. Lam, Chan-Feng Tsai Apr 1981

Soil-Pile Interaction In Liquefiable Cohesionless Soils During Earthquake Loading, Hudson Matlock, Geoffrey R. Martin, Ignatius P. Lam, Chan-Feng Tsai

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

A procedure for soil-pile-structure interaction analyses under earthquake loading is presented, using two computer programs: DESRA and SPASM. DESRA solves for free-field site response, including liquefaction, using a two-phase pore-pressure and effective stress soil model. Resulting displacement and pore pressure time histories are then transferred to SPASM for soil-pile-structure interaction solutions. The procedure is compared with a conventional approach consisting of a linear dynamic structural model and a separate nonlinear pseudo static pile model. The SPASM method was found to be useful in practical design of platforms to withstand earthquake loading. When significant superstructure-foundation interaction is expected, uncertainty in the …

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Embedment Effect On Foundations Under Vertical Vibrations, Swami Saran, Gopal Ranjan, R. C. Vijayvargiya Apr 1981

Embedment Effect On Foundations Under Vertical Vibrations, Swami Saran, Gopal Ranjan, R. C. Vijayvargiya

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

The dynamic response of the embedded foundation subjected to vertical dynamic loads has been studied through carefully conducted field tests. The block was excited in vertical and coupled modes of vibrations. Four excitation levels were used. Tests, with different embedment depths were carried out. The foundation block was instrumented to monitor dynamic contact pressure at various embedments with specially designed contact pressure cells. Side shear resistances were measured through dynamic shear resistance cells specially designed for the purpose. Also, frequency amplitude characteristics were observed during each test .The analysis of data indicates that as the depth of embedment increases, damping …

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Axisymmetric Soil-Structure Interaction By Substructure Approach, P. K. Basu, B. J. Lee Apr 1981

Axisymmetric Soil-Structure Interaction By Substructure Approach, P. K. Basu, B. J. Lee

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

The effect of soil-structure interaction is incorporated into an existing finite element computer program for axisymmetric shells and plates using substructure approach and energy transmitting boundaries. The results of numerical experimentation for a tall chimney and a typical hyperboloidal cooling tower are presented.

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Session 4: Opening Remarks, K. Rainer Massarsch Apr 1981

Session 4: Opening Remarks, K. Rainer Massarsch

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

No abstract provided.

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Seismic Response Of Pile Supported Structures, William E. Saul, Tuncer B. Edil, Yong-Wu Chang Apr 1981

Seismic Response Of Pile Supported Structures, William E. Saul, Tuncer B. Edil, Yong-Wu Chang

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

Earthquake loads are applied to the foundation mainly through shear waves in the underlying soil. A method is presented for analyzing the alteration in the response of a structure by adding piling to the foundation. The method of computation consists of a series of transfer matrices which are used to form a stiffness matrix of the foundation system. Central to the computation is the modelling mode for the soil-pile interaction; several alternatives are presented. Observations regarding the effect of several design parameters, based on a numerical example, are discussed.

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Studies Of Apparent Seismic Wave Velocity, A. H. Hadjian, D. M. Hadley Apr 1981

Studies Of Apparent Seismic Wave Velocity, A. H. Hadjian, D. M. Hadley

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

Apparent seismic wave velocities are studied by comparing the stress results obtained by a computer simulation with those obtained by a commonly used simplified engineering model. Two earth models with significantly different surface layers and two focal depths of energy release are used. The results from all four cases studied show that the apparent wave velocity at the free surface is determined by the properties of the material at depth where energy is released. A secondary, yet significant conclusion is the fact that the simplified plane wave propagation solution is a good predictor of the strains/stresses due to seismic waves, …

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Dynamic Response Of Rigid Circular Footings, Shenbaga R. Kaniraj Apr 1981

Dynamic Response Of Rigid Circular Footings, Shenbaga R. Kaniraj

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

In a simplified approach to the rigorous elastic half-space approach for the behavior of a rigid circular surface footing acted upon by a dynamic excitation force, the elastic half-space model is replaced by an equivalent lumped parameter system. The equivalent spring constant (K) and the equivalent damping factor (D) are expressed in terms of dimensionless mass ratio (B). A chance in the value of B thus affects the dynamic response of the footing. The paper explains a procedure to quantify this variation £or vertical mode of vibration.

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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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