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Articles 179971 - 180000 of 197988

Full-Text Articles in Engineering

Guerrero Accelerograph Array: Status And Selected Results, J. G. Anderson, A. Mendez, R. Quaas, J. N. Humphrey, R. Castro, S. K. Singh Mar 1991

Guerrero Accelerograph Array: Status And Selected Results, J. G. Anderson, A. Mendez, R. Quaas, J. N. Humphrey, R. Castro, S. K. Singh

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

This paper summarizes the history and rational for installation of the Guerrero accelerograph array. The array is producing unprecedented quantities of high quality digital strong motion data. Recent research using the array data has included studies on attenuation, site effects, scaling of spectra with magnitude, the ratio of vertical to horizontal accelerations, and the source of the September 19, 1985 earthquake.

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Seismic Risk Analysis For A Site Along The Gorda Segment Of The Cascadia Subduction Zone, Ronald C. Chaney, Guy Conversano, Gary Carver, David N. Lindberg, Frank Bickner Mar 1991

Seismic Risk Analysis For A Site Along The Gorda Segment Of The Cascadia Subduction Zone, Ronald C. Chaney, Guy Conversano, Gary Carver, David N. Lindberg, Frank Bickner

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

A seismic risk evaluation was conducted on a site near Eureka, California. The site was subject to potential earthquake loading from a number of sources. These sources were: (1) Mendocino Fracture Zone, (2) Gorda Segment of the Cascadia Subduction Zone, (3) Little Salmon thrust fault under the site, (4) Mad River Fault Zone, and (5) Intra plate west - Gorda Plate. The geology of thrust faults in Northern California is examined along with that of the Mendocino Fracture Zone, and the southern section (Gorda Segment) of the Cascadia subduction zone. A trench log showing a splay of the Little Salmon …

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A Numerical Solution Of Wave Equation For Dynamic Compaction Of Soil, K. B. Agarwal, B. Siva Ram Mar 1991

A Numerical Solution Of Wave Equation For Dynamic Compaction Of Soil, K. B. Agarwal, B. Siva Ram

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

It is a known fact that any disturbance at the ground surface, like the one created by vibratory, compactors or by application of blast pressure on detonation of a foamed propellant, is transmitted into ground until it is weak enough to travel deeper and farther. The ground acceleration at various points, induces compaction. The transmission of vibrations due to such surface dynamic loads are governed by the equation of motion based on Newton's second law. The equation of motion is presented in Euiler's Coordinates using tensor notation and is solved for surface displacements due to surface dynamic loads. These loads …

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Analysis Of Damping In Soil As Applied To Machine Foundations, B. M. Basavanna, M. S. Nagakumar Mar 1991

Analysis Of Damping In Soil As Applied To Machine Foundations, B. M. Basavanna, M. S. Nagakumar

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

The parameters needed for the design of machine foundations are usually evaluated from the model block resonance test conducted at a given site. Sometimes it may not be possible to attain complete resonance and the test results may be limited to the ascending part of the response. In this paper the possible effect of damping on the values of the design parameters evaluated from the ascending part of response is examined and the nature of damping which gives realistic values of design parameters is presented.

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Pile Driving Analysis: Two-Phase Finite Element Approach, P. Hölscher Mar 1991

Pile Driving Analysis: Two-Phase Finite Element Approach, P. Hölscher

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

The pile-driving process is analysed using the dynamic finite element program SATURN. The soil is modelled as a two-phase (skeleton and water) axi-symmetric continuum. The elasto-plastic behaviour of the skeleton is considered. Energy dissipation due to radiation, plastic deformation and water-skeleton friction is taken into account. The importance of permeability of the soil, its strength and its dilatancy are outlined. The soil resistance under the toe is strongly influenced by the low compressibility of the water. The results of the simulations show that the non-linear soil behaviour around the pile toe cannot be simulated satisfactorily using a single phase material. …

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Dedication To Harry B. Seed, Shamsher Prakash Mar 1991

Dedication To Harry B. Seed, Shamsher Prakash

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

No abstract provided.

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Earthquake Potential Along The Hayward Fault, California, Glenn Borchardt, J. David Rogers Mar 1991

Earthquake Potential Along The Hayward Fault, California, Glenn Borchardt, J. David Rogers

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

The Loma Prieta event probably marks a renewed period of major seismic activity in the San Francisco Bay Area. Particularly ominous is the historic record of major events a few years apart on opposite sides of the Bay in 1836 (N. Hayward fault) and 1838 (N. Peninsula, San Andreas fault) and 1865 (Loma Prieta segment, San Andreas fault), and 1868 (S. Hayward fault) (Figure 1). Recent preliminary measurements of the Holocene geologic slip rate of the Hayward fault are as much as 9 mm/yr (Lienkaemper and others 1989) - about 80% greater than the first Holocene measurements determined as recently …

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General Report, Loma Prieta Earthquake Sessions, Mary Ellen Hynes Mar 1991

General Report, Loma Prieta Earthquake Sessions, Mary Ellen Hynes

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

No abstract provided.

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Lifeline And Geotechnical Aspects Of The 1989 Loma Prieta Earthquake, T. D. O'Rourke, H. E. Stewart, T. E. Gowdy, J. W. Pease Mar 1991

Lifeline And Geotechnical Aspects Of The 1989 Loma Prieta Earthquake, T. D. O'Rourke, H. E. Stewart, T. E. Gowdy, J. W. Pease

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

This paper provides an overview of areas in San Francisco which were affected by soil liquefaction and significant ground deformation as a result of the Loma Prieta earthquake. The distribution of pipeline system damage is examined, and comparisons are made between 1989 and 1906 patterns of water supply damage. Special attention is given to the Marina to illustrate how the natural site conditions and artificial fills contributed to soil liquefaction and buried pipeline damage of both the water and gas distribution networks. Finally, the liquefaction potentials of natural beach and sand bar deposits, land-tipped fill, and hydraulic fill are evaluated …

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Performance Of Earth Dams During The Loma Prieta Earthquake, Leslie F. Harder Jr. Mar 1991

Performance Of Earth Dams During The Loma Prieta Earthquake, Leslie F. Harder Jr.

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

The October 17, 1989 Lorna Prieta Earthquake shook a large number of earth and rockfill darns. There were actually more than 100 darns within 50 miles of the fault rupture associated with this event. Although more than half of these embankments were less than 60 feet in height, a number of major darns were strongly shaken. In general, the darns performed satisfactory with one major darn and one minor darn developing moderate damage. A small number also developed minor to moderate cracking which required repairs. The great majority, however, sustained no significant damage. Although this result is quite encouraging, this …

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Prediction Of Loma Prieta Earthquake And Creation Of Awareness About It In Society, Arun Bapat Mar 1991

Prediction Of Loma Prieta Earthquake And Creation Of Awareness About It In Society, Arun Bapat

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

Prediction of earthquake as an exercise of academic interest is one activity. Creation of awareness about seismic disaster and its mitigation is more broad base social activity. It is necessary that the predicted seismic event is likely to occur, people in the vulnerable seismic area should be told about the utility of macroseismic, short-term reliable earthquake precursors, which could be observed by common man. The happenings involving both the above cases for Loma Prieta earthquake are discussed.

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Study Of Co-Seismic Planetary Conditions For Earthquake Prediction, R. N. Ketkar, M. N. Viladkar, P. N. Agrawal Mar 1991

Study Of Co-Seismic Planetary Conditions For Earthquake Prediction, R. N. Ketkar, M. N. Viladkar, P. N. Agrawal

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

The periodicities in the occurrence of earthquakes, as indicated by the cosmic conditions, have been traced by analysing the planetary data at the time of occurrence of more than 1100 earthquakes of magnitude, M 27.0, which occurred during the period 1896 to 1965. Correlation between the transits of planets in the sensitive areas and at sensitive longitudes in the zodiac and the seismicity of California and adjoining area has been shown. Based on the analysis, a method for forecasting earthquakes is also proposed.

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System Identification And Seismic Performance Evaluation Of Earth Dams, H. S. Sayed, A. M. Abdel-Ghaffar, S. F. Masri Mar 1991

System Identification And Seismic Performance Evaluation Of Earth Dams, H. S. Sayed, A. M. Abdel-Ghaffar, S. F. Masri

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

A system identification technique is developed to provide dynamic properties of earth dams from their seismic records. The technique is utilized to assess the capabilities and limitation of analytical models in terms of dynamic nonlinear constitutive relationships as well as damping. The technique is based on the least square method using Gaussian hypothesis. Earth dams are modeled as a three-dimensional nonhomogeneous visco-elasto-plastic soil structure. The forward problem is solved using a Galerkin-Ritz formulation in which the solution is expanded using basis function, which is selected to be the eigenmodes. The spatial variation of the excitation is considered by using global …

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The Loma Prieta Earthquake: Implications Of Structural Damage, S. A. Mahin Mar 1991

The Loma Prieta Earthquake: Implications Of Structural Damage, S. A. Mahin

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

The Loma Prieta earthquake provides a wealth of information on the seismic response of a wide variety of structures over a large metropolitan area. Soil amplification at sites distant from the epicenter contributed significantly to the substantial damages developed during the earthquake. Because of the large shaken area, the earthquake provides much useful information for all those interested in earthquake engineering. Structural damages resulting from the earthquake are reviewed herein with emphasis on buildings and bridges. Implications for modern design and retrofit methods are highlighted. Emphasis is placed on the need to carefully consider soil conditions, to treat the structure …

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Contributed Papers: Discussions And Replies, T. Kagawa Mar 1991

Contributed Papers: Discussions And Replies, T. Kagawa

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

No abstract provided.

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Panel Reports: Discussions, Multiple Authors Mar 1991

Panel Reports: Discussions, Multiple Authors

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

No abstract provided.

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Soil-Pile Interaction Model For Earthquake Response Analysis Of Offshore Pile Foundations, Toyoaki Nogami Mar 1991

Soil-Pile Interaction Model For Earthquake Response Analysis Of Offshore Pile Foundations, Toyoaki Nogami

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

No abstract provided.

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Banquet Speeches And Remarks, Shamsher Prakash, Shiming Wu, Kenji Akino, John T. Park, Joseph H. Senne, Jeanne L. Senne Mar 1991

Banquet Speeches And Remarks, Shamsher Prakash, Shiming Wu, Kenji Akino, John T. Park, Joseph H. Senne, Jeanne L. Senne

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

No abstract provided.

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A Cyclic Shear-Volume Coupling And Pore Pressure Model For Sand, Peter M. Byrne Mar 1991

A Cyclic Shear-Volume Coupling And Pore Pressure Model For Sand, Peter M. Byrne

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

A two parameter incremental shear-volume coupling equation is presented for sand. The equation is based upon experimental data and gives predictions that are in excellent agreement with data over a range of relative densities and stress conditions. Empirical expressions for the two parameters based on incorporated in a simple shear pore pressure element model and the predictions of the model are compared with both saturated undrained cyclic strain and cyclic load tests. It is found that, provided a threshold strain is incorporated, the model predictions are in very good agreement with the laboratory data over a wide range of stress …

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A Cyclic Triaxial Facility For Loading A Silty Clay, Matthew Raybould Mar 1991

A Cyclic Triaxial Facility For Loading A Silty Clay, Matthew Raybould

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

A digital control servo-hydraulic triaxial test facility with full data acquisition has been developed at Nottingham University as part of the UK Science and Engineering Research Council initiative in earthquake engineering. This apparatus is currently being used to investigate the response of a coarse silt contaminated by kaolin clay to cyclic stress and strain. High quality deformation data is generated by on sample instrumentation and enables the stiffness at very low strain levels to be determined accurately. This paper describes the development of the facility and presents some results of the tests carried out to date.

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An Estimation Of Dynamic Properties Of Soils From Block Vibration Tests, V. D. Miglani Mar 1991

An Estimation Of Dynamic Properties Of Soils From Block Vibration Tests, V. D. Miglani

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

The paper presents departures that have to be made in the conduct of block vibration tests from the standard method and in the analysis of test data under unusual conditions. Disturbed soil condition under an edge of the block leads to occurrence of double peaks in amplitude versus frequency curves from vertical vibration test. Two methods have been devised to analyze such double peaks. The first method assumes a correlation between dynamic coefficients. The dynamic properties can be predicted from non-dimensional curves of correction factor versus ratio of effective base area. The second method assumes linear variation of coefficient of …

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Behavior Of A Geosynthetic Reinforced Sand, H. C. Liu, N. Y. Chang Mar 1991

Behavior Of A Geosynthetic Reinforced Sand, H. C. Liu, N. Y. Chang

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

The method of geosynthetic reinforced earth incorporates a flexible but tension resistant synthetic material in soil to increase the tensile resistance of the composite. In this study, both static and dynamic responses of an Ottawa 30-40 sand reinforced with a nonwoven geosynthet1c, Bidim C-34, were investigated. Static triaxial tests were first conducted to examine the influence of the reinforcement on strength, Young's modulus, and Poisson's ratio of the composite soil. Cyclic triaxial tests and resonant column tests were then conducted to examine the variation of shear modulus and damping ratio at different strain amplitudes. The influence of geosynthetic on both …

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Behavior Of Geotextile Reinforced Soil Under Cyclic Loading, G. Venkatappa Rao, G. P. Singh, K. K. Gupta Mar 1991

Behavior Of Geotextile Reinforced Soil Under Cyclic Loading, G. Venkatappa Rao, G. P. Singh, K. K. Gupta

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

The vast potential of geotextiles for separation (reinforcement in pavements and rail roads is yet to be fully exploited in India, despite the initial successful trials. This is partly due to the lack of sufficient test data on the behavior under repetitive loading of indigenous geotextiles. This paper reports typical triaxial test results on reinforced and unreinforced specimens before and after cyclic loading. The reinforcement used is a needle punched polypropylene geotextile manufactured in India. The results reported include strength before and after cyclic loading (cyclic loading under both drained and undrained conditions), modulus of resilience and plastic strain. Limited …

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Deformation Of Sand Under Cyclic Simple Shear Loading, Chung-Jung Lee Mar 1991

Deformation Of Sand Under Cyclic Simple Shear Loading, Chung-Jung Lee

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

The deformation behavior of sand under simple shear loading was studied. The relation between the shear stress ratio and fabric factor, and the relationship between the fabric and dilatancy rate of a sand were developed. Thus the stress-dilatancy relation for sand was derived. Adopting the concept that the volumetric changes of the sample induced by the cyclic shear stress were compensated by the volumetric changes due to vertical stress changes in the constant volume simple shear tests, the relation of shear stress ratio and vertical stress change was derived.

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Development Of Shear Modulus Reduction Curves Based On Lotung Downhole Ground Motion Data, C.-Y. Chang, Y. K. Tang, C. M. Mok, H. T. Tang, M. S. Power, J. C. Stepp Mar 1991

Development Of Shear Modulus Reduction Curves Based On Lotung Downhole Ground Motion Data, C.-Y. Chang, Y. K. Tang, C. M. Mok, H. T. Tang, M. S. Power, J. C. Stepp

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

In this study, equivalent shear moduli (or shear-wave velocities) and their variations with shearing strain at the Lotung seismic experiment site were back-calculated from recorded downhole array ground motions. Ground motion data for various levels of shaking (peak ground surface accelerations ranging from 0.03g to 0.21g) recorded during seven earthquakes were used in the analyses. Results show that downhole array ground motion data can be used to infer in-situ dynamic soil properties over a wide strain range.

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Session 1: Discussions And Replies, Multiple Authors Mar 1991

Session 1: Discussions And Replies, Multiple Authors

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

No abstract provided.

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Electrical Conductivity For Evaluating Fabric And Mechanical Behavior Of Granular Soils, Lien Kwei Chien, J. C. Li Mar 1991

Electrical Conductivity For Evaluating Fabric And Mechanical Behavior Of Granular Soils, Lien Kwei Chien, J. C. Li

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

In this study, an auto-compensation conductivity measurement system has been developed. This system is expected to offer a possible means for describing the granular soil fabric and mechanical behaviors. A series of cyclic triaxial compression, extension, and unloading tests with resistance measurement were performed. The correlation between granular soil friction angle φ, and vertical formation factor, Fv under maximum shear stress ratio has been studied. The test results have shown that the electrical conductivity could be used to evaluate the fabric behavior during the process of loading. The fabric ellipsoid function, which has been used to simulate the orientation …

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Energy-Absorbing Ability Of Texsol, Phong M. Luong Mar 1991

Energy-Absorbing Ability Of Texsol, Phong M. Luong

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

Texsol is a 30 soil-fiber composite, obtained using a technique of soil reinforcement by incorporation of continuous textile fibers. The overall mechanical properties of Texsol result therefore from those of its components: soil and fibers. An experimental approach has been carried out in order to grasp the basic aspects of the stress-strain response of Texsol subjected to monotonic, cyclic and vibratory loadings. The study confirms that the application of Texsol to earthquake resistant earthworks and traffic structures could be of great interest and particularly suitable as shown by its ductility and energy-absorbing capacities that are readily evidenced by the laboratory …

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In Situ Torsional Cylindrical Shear Test-Laboratory Results, W. Henke, R. Henke Mar 1991

In Situ Torsional Cylindrical Shear Test-Laboratory Results, W. Henke, R. Henke

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

We present results from cyclic tests conducted in the laboratory using a prototype in situ cyclic torsional cylindrical shear geotechnical testing system. The system is intended to advance our ability to design critical systems to resist earthquakes by improving our ability to analytically predict the behavior of soil-structure-equipment systems during earthquakes. It is to do so by providing, more reliably than we feel is now possible, estimates of the in situ cyclic shear stress vs strain characteristics needed by refined earthquake analyses. These characteristics include 1) resistances to initial liquefaction, cyclic degradation, and large cyclic deformations, and 2) undegraded, nonlinear, …

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Lnsitu Measurement Of Damping Of Soils, W. P. Stewart, R. G. Campanella Mar 1991

Lnsitu Measurement Of Damping Of Soils, W. P. Stewart, R. G. Campanella

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

The Seismic Cone Penetration Test (SCPT) has been shown to give reasonable results for insitu measurements of shear wave velocity, and this paper extends this work to include measurements of damping. The relevant equations of motion are described, factors affecting amplitude decay are discussed, and the nature of damping is summarized. Consideration is given to some of the practical aspects of pre-processing of signals. Three methods of damping calculation are presented. The first two, attenuation coefficient and modified SHAKE methods, require the application of amplitude corrections, which is not straight-forward, give variable results, and indicate negative damping in a clayey …

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