Accuracy of Methods Using Driving Resistance for Predicting Axial Pile Capacity
J. H. Long,* B. Leoro
University of Illinois

Improvements for estimating pile capacity have been made in recent years by instrumenting piles, monitoring their behavior during driving and during retapping, and modeling their dynamic response. A database of load tests on driven piling is being used to assess the accuracy at which these methods can predict axial capacity. The database consists of over 100 piles in which dynamic measurements, wave equation analyses, and static load tests were conducted. Each method is being compared in terms of accuracy and in terms of cost of the resulting foundation. Effects of setup and relaxation for driven piling are also being used to study and quantify time effects and their effect on pile capacity.

Axial Capacity of Drilled Shafts in Sand
J. H. Long,* C. Berger
University of Illinois; Hanson Engineers, Inc.

Relationships for the behavior of sands are being used to develop a method to predict the axial capacity of drilled shafts in sand. These relationships are based on characteristics of the soil, such as grain size, soil density, dilational behavior, and the stress at failure along the perimeter of the drilled shaft. Results of soil tests will be used to develop relationships for the soil behavior and design charts for the resistance provided by the soil. Results of axial load tests on drilled shafts are being used to calibrate the model.

Beneficial Use of Shredded Tires in Covering Abandoned Landfills
T. D. Stark,* D. E. Daniel,* K. R. Reddy*
Department of Commerce and Community Affairs

Approximately 279 million used automobile, truck, and specialty tires are discarded each year nationwide. The unshredded tires disposed in landfills tend to 'float' to the surface, breaking the landfill cover and causing increased leachate production which could contaminate groundwater. Therefore, many states have banned disposal of whole tires in landfills. The objective of this research is to perform a comprehensive study involving both field and laboratory testing and to investigate the feasibility of using shredded tires as a drainage material in cover systems for waste containment systems.

Compressibility and Consolidation of Soils
G. Mesri,* T. W. Feng, M. M. Shahien
University of Illinois

This research program is concerned with compressibility and consolidation of soft clay and silt deposits. The uniqueness principle of soil compressibility is being investigated by means of laboratory measurements of consolidation of half-a-meter thick natural soft clay specimens. This principle allows direct application of compressibility information from small-scale laboratory tests to full-scale field settlement problems. Surcharging of soft clays, peats, and silts for ground improvement is another subject of this investigation. Surcharging is used to speed up ground modification and minimize postconstruction deformation damage to structures. The objective is to develop a methodology for engineering surcharging operations.

Coupled Hydraulic-Mechanical Behavior of Jointed Rock Masses with Applications to Pressure Tunnels
E. J. Cording,* G. Fernandez,* S. Choi, S. Lee
National Science Foundation, CMS 96-10545

Failure and leakage of high-pressure water tunnels have occurred when the effect of geologic features, such as rock joints and in situ stresses, on hydraulic behavior were not adequately considered. In this study, the coupled hydromechanical behavior of rock joints surrounding lined pressure tunnels is investigated using the discrete finite-element method. Procedures have been developed in this study to excavate the tunnel and install a lining and to accommodate joint dilatancy with shear. Stresses and flow in the jointed rock mass are observed as the tunnel is excavated and pressurized. A series of rock slope and rock joint geometries are being modeled and results compared with pressure tunnel cases and existing design criteria.

Design and Performance of Tied-Back Excavation Walls
J. H. Long,* E. J. Cording,* J. Ghaboussi, C. Mueller, G. Larson
Federal Highway Administration; Schnabel Foundation Co.

Ground movements and the distribution of stresses on an excavation wall are dependent on construction procedures and the relative stiffness of the support elements with respect to the soil. These characteristics are being studied using numerical analyses, full-scale field tests, and large-scale model tests. Model tied-back walls constructed in the soil model test facility will be tested to determine displacements and stresses resulting from normal construction sequences, as well as failure. Model performance will be compared with finite-element analyses, and techniques will be developed that will permit analysis of both limit equilibrium and soil-structure interaction effects.

Determination of the Axial Capacity of Drilled and Grouted Piles Using a Database of Load-Test Data on Drilled Foundations
J. H. Long,* M. Wysockey
Amoco, Exxon, Mobil, Shell, ADSC; The Association of Foundation Drilling; Shell Foundation Faculty Fellowship

Drilled and grouted piles offer advantages over driven piles when driving is uneconomical or impractical because of subsurface and environmental conditions, such as very deep water, very hard driving conditions, or calcareous soils. The goal of this project is to develop design/analysis procedures for predicting the axial load capacity of drilled and grouted piles (and drilled foundations) based upon a large database collection of results from load tests on drilled foundations. Currently, over 950 load tests on drilled foundations (drilled and grouted piles, drilled shafts, auger-cast piles, and tiebacks) have been collected. The database of load tests is being used to provide insight regarding the effect of length, diameter, construction procedure, grout pressure, soil type, etc.

Electrical Treatment of Soils
G. Mesri,* V. Schifano
University of Illinois

Electrical flow of pore fluid and associated electrochemical reactions have been used for permanent or temporary stabilization of soft clay and silt deposits. Important manifestations are consolidation and associated deformations, improvement of mechanical properties resulting from consolidation and electrochemical hardening, and favorable porewater flow resulting in an increase in effective stress. Although considerable attention has been directed recently to electrokinetics as a means of cleaning contaminated ground, important uncertainties remain in relation to electrokinetic processes in soils as well as practical details of treatment. The physical and chemical processes are under detailed review and analyses for developing a formulation for predicting time-rate of electrochemical ground modification.

Embankment Stability Following Reservoir Drawdown
G. Mesri,* M. Alzoubi
National Science Foundation, CMS 95-30464

Embankment dams or dykes may experience undrained instability during rapid drawdown of the reservoir. Drainage may not occur in compacted clay of a homogeneous embankment or a core upon rapid drawdown. Undrained shear strength at yield of the compacted clay, consolidated under predrawdown shear stress and effective stress conditions, is required for stability analysis. Undrained strength may be expressed in terms of post-drawdown effective stress condition and strength parameters (ESSA), or in terms of predrawdown effective stress conditions and undrained shear strength ratios (USSA). Both approaches are being evaluated in laboratory undrained shear tests on saturated compacted clays and by full-scale stability analyses.

Foundation Improvement for Bridge Columns
J. H. Long,* B. Leoro, T. Hunt
NSF Mid-America Earthquake Center

The goal of this project is to investigate, experimentally and analytically, the use of micropiles and deep soil mixing as means of retrofitting existing foundations for bridge columns. Results of the project will provide the practicing engineer with information on the suitability of these two alternatives for the seismic retrofit of bridge foundations in the mid-America region. The study will assess the behavior of the original foundation and predict the retrofit behavior with micropiles and with deep soil mixing. The study will also identify the suitability of each method to seismic retrofit needs (e.g., lateral load, overturning, tension, etc.).

Foundation Remediation for Buildings
J. H. Long,* B. Leoro, T. Hunt
NSF Mid-America Earthquake Center

The goal of this project is to provide practicing engineers with detailed information for guidance in rehabilitating foundations of essential facilities in the mid-America region. The project will investigate methods for rehabilitating foundations under typical low-rise essential facilities. These methods will include both soil improvement and retrofit of existing foundations. Assessment of various methods for foundation remediation will include information on cost of implementation as well as the associated risks. Foundation remediation methods will be presented in a set of guidelines for practicing engineers, allowing them to develop and compare different strategies for rehabilitating foundations.

Friction-bearing Design of Steel H-Piles
J. H. Long,* M. Wysockey, M. Maniaci
Illinois Transportation Research Center, ITRC Project IA-H3

This effort is to assess current Illinois Department Transportation (IDOT) recommendations for estimating the axial capacity of friction H-piles driven in layered soils. The effort investigates methods for predicting axial capacity including (1) current IDOT recommendations (IDOT Specification Art. 512.14), (2) conventional methods that include soil strength parameters, (3) wave equation analysis (WEAP), and (4) pile driving analyzer (PDA) results. The scope of this effort will include monitoring pile response during driving and conducting axial load tests on H-piles driven at a minimum of three construction sites in Illinois. The results of the study will be used to provide recommendations to IDOT for improving estimates of axial capacity for friction H-piles.

Geotechnical Properties of Peat
G. Mesri,* M. A. Ajlouni
University of Illinois

Peatlands constitute 5% to 8% of the world's land. Peat deposits, the remains of plants, have a chemical composition and structure significantly different from those of inorganic soils. Peat exists at very high water contents and displays very large compressibility. It is no longer economical to avoid peat deposits in siting of infrastructure, including transportation facilities. Innovative engineering requires a fundamental understanding of peat behavior. Undisturbed samples of Middleton peat from Wisconsin and James Bay peat from Quebec are being used in a detailed laboratory study of geotechnical characteristics of peat.

Granular Soils Improved by Dynamic Methods
G. Mesri,* M. Smadi, B. Vardhanabhuti
National Science Foundation, CMS 95-30464

Geostatic horizontal stress plays a dominant role in ground response to in situ penetration tests that are frequently specified for the control of granular soil improvement by dynamic methods. These include densification by impluse loading, such as explosives or heavy tamping, and by steady vibration such as vibrocompaction. Each compaction method produces a different history of preshearing resulting in different magnitudes of horizontal stress in densified ground. Laboratory measurements of horizontal pressure in sand specimens that are densified by different impulse or steady vibration methods are intended for a better interpretation of post-densification penetration resistance.

Guidelines for Geofoam Applications in Embankments
T. D. Stark,* J. M. Horvath,* D. Leshchinsky,* D. Arellano
National Cooperative Highway Research Program, 24-11

The main objective of the proposed research is to develop guidelines for the use of geofoam, i.e., expanded polystyrene, as a super-lightweight fill in roadway embankments and bridge approaches over soft ground. These guidelines will facilitate the use of geofoam in civil engineering projects by providing engineers with design procedures, historical data, and durability information.

Hydromechanical Evaluation of Flow in Rock Foundations of Concrete Dams
G. Fernandez,* E. J. Cording,* E. Gimenes, S. H. Choi
National Science Foundation, CMS 96-10545

Case studies and numerical analyses are being used to investigate flow in jointed rock foundations of concrete dams and the resulting uplift pressures in concrete dams. Coupled hydromechanical numerical models are employed using the direct finite element method and UDEC, another discrete element method. The effect of reservoir loading and unloading and drainage beneath the dam foundation and their effect on joint aperture changes and uplift pressures are being studied.

Importance of Three-dimensional Slope Stability Methods
T. D. Stark,* D. Arellano
National Science Foundation, BCS 93-00043

The 1988 slope failure at the Kettleman Hills Waste Repository forced engineers to consider 3-D slope stability analyses. However, 3-D slope stability analyses are new and not readily available to practicing engineers or government agencies. The main objectives of the research are: (1) improved understanding of the accuracy and applicability of existing 3-D slope stability methods to field conditions, (2) clarifying the parameters or assumptions that significantly affect the 3-D factor of safety, (3) field situations, if any, where 3-D factors of safety are less than 2-D factors of safety, (4) improved understanding of 3-D effects on 2-D back-calculated shear strength parameters, and (5) importance of including 3-D effects in 2-D stability analyses.

Jacking Loads and Ground Deformations Associated with Microtunneling
R. D. Bennett,* E. J. Cording
U.S. Army Waterways Experiment Station

Tunneling with remotely operated, small-diameter machines is increasingly used in lieu of open trenching for installation of utilities. The performance of three tunneling machines was investigated by advancing them through test beds constructed at the Waterways Experiment Station containing a sequence of soil and groundwater conditions. These results, combined with results of field measurements on microtunneling projects in several natural soil deposits, are being used to investigate the effect of soil conditions, construction procedures, and tunnel machine design on the forces required to advance the pipe and the ground movements associated with the tunnel advance.

Lime Stabilization of Clay Slopes
G. Mesri,* D. Rydeen,* N. Schwanz,* M. Al-Zoubi, V. C. Schifano, M. M. Shahien
U.S. Army Construction Engineering Research Laboratories, DACW37-98-M-0458

Stability of levees and banks of the Red River has a profound influence on land use in adjacent communities. Slope movements damage adjacent structures, and during the spring 1997 flood, overtopping of levees caused catastrophic flooding in North Dakota and Minnesota. Programs are underway to stabilize river banks and improve the levee system. One scheme is lime treatment of river bank clays. Adsorption of calcium hydroxide, together with formation of calcium silicates and aluminates, may lead to aggregation of clay particles. Direct shear testing is being used to investigate a possible permanent increase in frictional resistance of lime-treated Brenna and Sherak formations.

Liquefaction Response of Soils in Mid-America
T. D. Stark,* S. M. Olson
NSF Mid-America Earthquake Center

Liquefaction is one of the most prevalent consequences and sources of damage resulting from seismic activity. Predictions of the liquefaction potential of loose saturated deposits of cohesionless material is an important activity in earthquake preparedness in any seismic region. This integrated experimental and analytical study seeks to improve the procedures by which liquefaction potential of sandy soils in the MAE region is assessed by considering the influence of region dependent factors such as the earthquake frequency content and the magnitude scaling factors.

Liquefaction-induced Permanent Deformations
T. D. Stark*
NSF Mid-America Earthquake Center

This study will evaluate the mechanisms that lead to liquefaction-induced permanent deformation in soils and embankments, namely liquefaction flow failure and liquefaction-induced lateral spreading. The study will focus on determining procedures to evaluate the shear strength of liquefied soils and their deformation characteristics from in situ test results. New and existing field case histories and high-quality laboratory test results will be evaluated to study these phenomena and will be used to investigate the application of a shear strength ratio to liquefied soils.

Long-Term Performance of Compacted Soil Liners
T. D. Stark,* D. E. Daniel,* A. J. Valocchi,* C. J. Werth,* I. G. Krapac*
Illinois Office of Solid Waste Research, OSWR-11-002

Although compacted soil liners are widely used for waste-containment facilities, there is little information on their long-term performance. A heavily instrumented soil liner (plan dimensions 8 m ? 15 m and 0.9 m thick) has been monitored for approximately eight years. Evaluation of the resulting data provides a unique opportunity to quantify the long-term advection and diffusion of compacted soil liners. In addition, excavation/dissection of the soil liner will provide insight to the variability of the effective diffusion coefficient, hydraulic productivity, and effect of compaction on soil micro- and macrofabric.

Long-Term Stability of Stiff Clay Slopes
G. Mesri,* M. M. Shahien
University of Illinois

The stability of stiff clay slopes is time-dependent because shear strength may deteriorate from the intact value to the residual condition. Because it is not readily possible to specify the dynamics of deterioration in terms of the environmental, hydrologic, and detailed geologic conditions, a precedent-based approach is used to forecast instability. The empirical method is constructed using back-analyses of failures of cut slopes of known age, together with interrelationships for intact and residual strength. For a stiff clay slope, it is possible to predict a stable age which may range from less than a year to over 200 years.

Measured Performance of Excavations and Jacked Tunnels for the Boston Central Artery/Tunnel Project
Y. M. A. Hashash,* E. J. Cording*
Federal Highway Administration

The Central Artery/Third Harbor Tunnel Project, under construction in Boston, Mass., is the largest public works project currently underway in the United States. The project includes placement of the highway underground and involves the construction of deep excavations using diaphragm walls and the largest jacked tunnels in the world below an operating railway line. This research project will use a vast electronic instrumentation database in conjunction with information that will be collected at significant construction stages to develop an understanding of the behavior of the diaphragm-wall-supported excavation systems and the jacked tunnels for CA/T.

PVC Geomembrane Institute Technology Program
T. D. Stark,* D. E. Daniel,* K. R. Reddy*
PVC Geomembrane Institute

A technology program was established for the PVC Geomembrane Institute to develop and disseminate information on PVC geomembranes. The PGI is a nonproduct, industry-based consortium founded in 1988 to convey the advantages and disadvantages of PVC geomembranes. The research that is conducted involves thermal seaming, interface strengths, durability, and chemical compatibility. The information dissemination involves publishing technical bulletins, reports, and papers, establishing and maintaining a website, conducting workshops and short courses, and incorporating the information in existing courses.

Paleoliquefaction and Paleoseismology in Mid-America
T. D. Stark,* S. M. Olson
NSF Mid-America Earthquake Center

Sites that experienced liquefaction and/or lateral spreading during the 1811-1812 New Madrid earthquakes and possibly during prehistoric earthquakes in the New Madrid seismic zone are being studied to improve the paleoearthquake chronology of the region. Geotechnical investigations are being performed at these sites to enhance understanding of the formation of the liquefaction features and to back-calculate the levels of ground shaking required to form these features. In addition, levels of ground motion inferred from this study will be used to improve ground motion estimates, earthquake magnitude estimates, and liquefaction hazard maps throughout mid-America.

Performance of Gasketed Precast Concrete Segments for Tunnel Linings
E. J. Cording,* S. L. Paul,* M. J. Rood, F. Shalabi, S-W. Lee
Los Angeles Metropolitan Transportation Authority

Precast concrete segments assembled in rings are used as both immediate and long-term tunnel support. Their ability to control leakage of gas and water when joints between segments are misaligned or subject to rotation and displacement during installation and subsequent seismic ground motions was investigated in a series of load, relaxation, and leakage tests on assemblies of gasketed concrete segments. Rates of methane and water leakage were determined as a function of gasket pressure and joint gap. Destructive testing was performed to evaluate and improve segment load capacity. Procedures were developed to control leakage with secondary joint grouting.

Performance of Segmented Tunnel Linings
S. Paul,* E. J. Cording, F. Shalabi, S. W. Lee
Los Angeles (California) Metro

Performance of gasketed concrete segments used for tunnel linings is being investigated under varying loading conditions, including cyclic loads and displacements equivalent to earthquake effects. The gaskets are pressurized with gas or water to determine their ability to prevent leakage under a range of loading conditions.

Performance of a Tunnel in Soft Clay
E. J. Cording,* N. Kawamura
University of Illinois; McNally Tunnelling Co.

A tunnel excavated in soft clays in the Chicago, Ill., area has been instrumented to evaluate the interaction of the tunnel shield machine and the installed lining with the ground. The tunnel was advanced through clusters of instruments that monitor vertical and lateral displacements and porewater pressures in the clay. Deformation and loads on the tunnel lining were measured as the lining was installed and as it took load with time. Effect of stress and pore pressure changes on immediate and long-term ground movements in the clay have been investigated. Ground behavior with current tunneling equipment and methods has been contrasted with earlier tunneling experience in Chicago and other tunnels in clay.

Secondary Compression of Peat
G. Mesri,* T. D. Stark,* M. A. Ajlouni
University of Illinois

Secondary compression is most important in peat deposits because they exist at high void ratios and exhibit high values of compression index Cc, display the highest values of Ca/Cc among geotechnical materials, and primary consolidation is completed in weeks or months in typical field situations. Secondary compression of Middleton peat was investigated by oedometer tests on undisturbed specimens. The observed secondary compression behavior of this fibrous peat, without or with surcharging, is completely in accordance with the Ca/Cc law of compressibility. It is possible to predict settlement of embankments on peat without and with surcharging. The next phase of the research concerns primary consolidation of peat.

Seismic Performance of Waterfront Structures
G. Mesri,* W. J. Hall,* R. M. Ebeling,* M. Shahein
NSF Mid-America Earthquake Center

This project investigates the seismic design of river and port facilities in the mid-American transportation network. The objectives of the research for mid-American waterfront structures are to: (1) examine performance during previous earthquakes, (2) identify the typical design conditions, (3) develop a simplified design procedure, (4) develop a fragility relationship for typical mid-American waterfront structures, and (5) prepare a brief nontechnical document for port owners and operators to alert them to the potential consequences of an earthquake in the region.

Settlement Resulting from Flow of Soil
G. Mesri,* M. Smadi
National Science Foundation, CMS 95-30464

Settlement of structures on soft clay deposits results from flow and consolidation of soil. In the latter case, water squeezes out from under the structure, whereas in the former case, soil squeezes out. Settlement resulting from flow of soil depends on the factor of safety against undrained instability. In construction situations where the factor of safety is small, an accurate prediction of settlement resulting from flow of soil is required. Field measurements of horizontal deformation of soft clays during construction of embankments and storage facilities are being used to develop a practical procedure for computing settlements resulting from flow of soil.

Settlement of Granular Soils Subjected to Static or Dynamic Loading
G. Mesri,* M. M. Shahien
National Science Foundation, CMS 95-30464

This research program is developing methodologies for settlement analysis of structures on granular soils subjected to repeated loading. Two independent methods based on in situ penetration tests are being evaluated using field performance records. One empirical method is based on the drive sampler penetration text (DSPT), and the second method uses push cone penetration test (PCPT) measurements. Settlements taking place during static or dynamic external loading and those that follow with time are being evaluated. Variables other than the condition of granular soil and nature of loading include depth of foundation and adjacent structures.

Soil Improvement by Vertical Drains
G. Mesri,* M. M. Shahien, M. A. Ajlouni
University of Illinois

The computer program ILLICON-I for settlement and pore water pressure analyses, which is based on a theory of consolidation developed at the U of I, has been successfully used for designing dykes on highly compressible clays and for analyzing case histories of test fills on soft ground. Embankment construction on deep deposits of highly compressible soils generally requires the use of vertical drains to speed up the hydrodynamic consolidation stage. The new generation of the program, ILLICON-II, includes all the features of ILLICON-I and incorporates partially or fully penetrating vertical drains with well-resistance and smear zone. The program is being used to analyze case histories of embankments on soft ground with sand or prefabricated drains.

Soil Strength of Liquified Soils
T. D. Stark,* S. M. Olson
National Science Foundation, CMS 95-31678

A method for estimating the shear strength ratio of liquefied soil using cone penetration test (CPT) results is being developed. The strength ratio from 30 field case histories of liquefaction flow failure and lateral spreading is being used to develop a relationship between equivalent clean sand corrected CPT tip resistance and mobilized strength ratio. This project also involves convening an international workshop to evaluate the state-of-the-art and state-of-the-practice of determining the shear strength of liquefied soil for use in stability and deformation analyses and to identify and prioritize research needs.

Stability of Colluvial Slopes
T. D. Stark*
National Science Foundation, CMS-9802615

This research project will address a number of objectives including: (1) determine the shear strength that is mobilized in a colluvial slope using natural and man-made case histories, (2) investigate the geologic and/or environmental conditions that result in development of a residual strength, (3) investigate the importance of soil plasticity, clay-size fraction, effective normal stress, etc., on the mobilized shear strength of colluvium, (4) investigate the importance of strain incompatibility on the development of a residual strength condition in colluvial slopes, and (5) develop design recommendations for the construction/expansion of natural and man-made slopes founded on colluvium.

Static and Dynamic Geosynthetic Interface Strengths
T. D. Stark,* R. Hillman
Illinois Office of Solid Waste Research, OSWR-07-001; PVC Geomembrane Institute

The stability of a composite liner or cover system for landfills and reservoirs is dependent upon the interface strength between the various components within the system. This study is developing a test methodology and a database of interface strengths for the various interfaces in a composite system. Torsional ring shear tests, instead of reversal direct shear, are being performed to investigate the interface strength and its degradation with shear displacement. The effect of displacement rate and flexible geomembranes are also being investigated to evaluate the dynamic interface strength. Case histories are being used to estimate the magnitude of the laboratory strength that is actually mobilized in the field.

Strength of Jointed Rock Masses
E. J. Cording,* O. Mughieda
University of Illinois

The strength and deformability of rock slopes and tunnels are largely controlled by natural fractures (joints) in the mass. To investigate these effects, a procedure was developed for forming parallel joints in a model rock material. A series of biaxial load-deformation tests were performed on 30 ? 30 ? 60-cm models containing nonpersistent joints of varying length, spacing, frictional strength, and orientation. The results have provided information on the strengthening effect of the rock bridges between joint segments. Reductions in strength result from conditions causing tensile stress concentrations, rotation or reduced confinement near the bridge, or progressive failure of multiple bridges.

Subsurface Construction, Resulting Ground Movements, and Protection of the Built Environment
E. J. Cording,* J. Long, D. Laefer, B. Ghahreman, T. Geilen, M. Son, J. Klecker
National Science Foundation, INT 97-22877, 97-13854; University of Illinois

Of prime concern in excavating or tunneling in urban areas is the protection of nearby structures and utilities from damage induced by ground movements. Case histories are being collected and observations are being made on projects in which ground movements and building response have been measured in the U.S. as well as in Seoul, South Korea, and London, England. Numerical analyses of wall-soil and building-soil interaction are underway. Planned are a series of model building experiments in the Illinois large soil model test facility. Workshops will be conducted with engineers, contractors, and preservationists to develop guidelines for evaluating, monitoring, and controlling ground movements affecting buildings.

Three-dimensional Basin Response
Y. M. A. Hashash,* E. Kausel* (MIT)
NSF Mid-America Earthquake Center

Ground motion simulations well constrained by geological and seismic data are an important resource for assessing hazard and designing earthquake-resistant structures, especially in urban areas in the central U.S. where damaging earthquakes are largely unknown and where many buildings have poor seismic resistance. This project will assess the basin effects in the Memphis, Tenn., area and carry out analyses with simple analytical methods, including one- and two-dimensional models. The results of this study will provide valuable information for developing seismic risk maps and designing codes appropriate for the region.

Visualization for Constitutive Relations in Engineering
Y. M. A. Hashash*
NCSA/U of I Faculty Fellowship Program

Material constitutive relations or models are mathematical representations of the mechanical response of material and relate stress and strain states of the material in a three-dimensional space. The relations in addition include descriptions of geometric shapes to represent yield and failure surfaces. This research explores the use of advanced computer visualization techniques and graphics to represent these relations. The visual representation will facilitate the interpretation of three-dimensional states of stress and stress and the influence of a constitutive relation on their evolution due to specified loading conditions.