Over the years, many methods have been developed to predict the settlement of shallow foundations on cohesionless soils. However, methods for making such predictions with the required degree of accuracy and consistency have not yet been developed. Accurate prediction of settlement is essential since settlement, rather than bearing capacity, generally controls foundation design. In this paper, artificial neural networks (ANNs) are used in an attempt to obtain more accurate settlement prediction. A large database of actual measured settlements is used to develop and verify the ANN model. The predicted settlements found by utilizing ANNs are compared with the values predicted by three of the most commonly used traditional methods. The results indicate that ANNs are a useful technique for predicting the settlement of shallow foundations on cohesionless soils, as they outperform the traditional methods.

Predicting settlement of shallow foundations using neural networks

Effectiveness of Class C fly ash as an expansive soil stabilizer

The interaction action between structures and supporting soil media is of fundamental importance in foundation design and it has always attracted the attention of both researchers and engineers. This paper reviews the state-of-the-art in this field, highlighting the key areas of development, including the modelling of the soil media and various analytical as well as numerical approaches in analysing the interaction action between the foundation and soil. Copyright © 2005 John Wiley & Sons, Ltd.

Beams and plates on elastic foundations: a review

This report describes a state-of-the-art performance-based earthquake engineering methodology 
that is used to assess the seismic performance of a four-story reinforced concrete (RC) office 
building that is generally representative of low-rise office buildings constructed in highly seismic 
regions of California. This “benchmark” building is considered to be located at a site in the Los 
Angeles basin, and it was designed with a ductile RC special moment-resisting frame as its 
seismic lateral system that was designed according to modern building codes and standards. The 
building’s performance is quantified in terms of structural behavior up to collapse, structural and 
nonstructural damage and associated repair costs, and the risk of fatalities and their associated 
economic costs. To account for different building configurations that may be designed in 
practice to meet requirements of building size and use, eight structural design alternatives are 
used in the performance assessments. 
Our performance assessments account for important sources of uncertainty in the ground 
motion hazard, the structural response, structural and nonstructural damage, repair costs, and 
life-safety risk. The ground motion hazard characterization employs a site-specific probabilistic 
seismic hazard analysis and the evaluation of controlling seismic sources (through 
disaggregation) at seven ground motion levels (encompassing return periods ranging from 7 to 
2475 years). Innovative procedures for ground motion selection and scaling are used to develop 
acceleration time history suites corresponding to each of the seven ground motion levels. 
Structural modeling utilizes both “fiber” models and “plastic hinge” models. Structural 
modeling uncertainties are investigated through comparison of these two modeling approaches, 
and through variations in structural component modeling parameters (stiffness, deformation 
capacity, degradation, etc.). Structural and nonstructural damage (fragility) models are based on 
a combination of test data, observations from post-earthquake reconnaissance, and expert 
opinion. Structural damage and repair costs are modeled for the RC beams, columns, and slabcolumn connections. Damage and associated repair costs are considered for some nonstructural 
building components, including wallboard partitions, interior paint, exterior glazing, ceilings, 
sprinkler systems, and elevators. The risk of casualties and the associated economic costs are 
evaluated based on the risk of structural collapse, combined with recent models on earthquake 
fatalities in collapsed buildings and accepted economic modeling guidelines for the value of 
human life in loss and cost-benefit studies. 
The principal results of this work pertain to the building collapse risk, damage and repair 
cost, and life-safety risk. These are discussed successively as follows. 
When accounting for uncertainties in structural modeling and record-to-record variability 
(i.e., conditional on a specified ground shaking intensity), the structural collapse probabilities of 
the various designs range from 2% to 7% for earthquake ground motions that have a 2% 
probability of exceedance in 50 years (2475 years return period). When integrated with the 
ground motion hazard for the southern California site, the collapse probabilities result in mean 
annual frequencies of collapse in the range of [0.4 to 1.4]x10
-4
 for the various benchmark 
building designs. In the development of these results, we made the following observations that 
are expected to be broadly applicable: 
(1) The ground motions selected for performance simulations must consider spectral 
shape (e.g., through use of the epsilon parameter) and should appropriately account for 
correlations between motions in both horizontal directions; 
(2) Lower-bound component models, which are commonly used in performance-based 
assessment procedures such as FEMA 356, can significantly bias collapse analysis results; it is 
more appropriate to use median component behavior, including all aspects of the component 
model (strength, stiffness, deformation capacity, cyclic deterioration, etc.); 
(3) Structural modeling uncertainties related to component deformation capacity and 
post-peak degrading stiffness can impact the variability of calculated collapse probabilities and 
mean annual rates to a similar degree as record-to-record variability of ground motions. 
Therefore, including the effects of such structural modeling uncertainties significantly increases 
the mean annual collapse rates. We found this increase to be roughly four to eight times relative 
to rates evaluated for the median structural model; 
(4) Nonlinear response analyses revealed at least six distinct collapse mechanisms, the 
most common of which was a story mechanism in the third story (differing from the multi-story 
mechanism predicted by nonlinear static pushover analysis); 
(5) Soil-foundation-structure interaction effects did not significantly affect the structural 
response, which was expected given the relatively flexible superstructure and stiff soils. 
The potential for financial loss is considerable. Overall, the calculated expected annual 
losses (EAL) are in the range of $52,000 to $97,000 for the various code-conforming benchmark 
building designs, or roughly 1% of the replacement cost of the building ($8.8M). These losses 
are dominated by the expected repair costs of the wallboard partitions (including interior paint) and by the structural members. Loss estimates are sensitive to details of the structural models, 
especially the initial stiffness of the structural elements. Losses are also found to be sensitive to 
structural modeling choices, such as ignoring the tensile strength of the concrete (40% change in 
EAL) or the contribution of the gravity frames to overall building stiffness and strength (15% 
change in EAL). 
Although there are a number of factors identified in the literature as likely to affect the 
risk of human injury during seismic events, the casualty modeling in this study focuses on those 
factors (building collapse, building occupancy, and spatial location of building occupants) that 
directly inform the building design process. The expected annual number of fatalities is 
calculated for the benchmark building, assuming that an earthquake can occur at any time of any 
day with equal probability and using fatality probabilities conditioned on structural collapse and 
based on empirical data. The expected annual number of fatalities for the code-conforming 
buildings ranges between 0.05*10
-2
 and 0.21*10
-2
, and is equal to 2.30*10
-2
 for a non-code 
conforming design. The expected loss of life during a seismic event is perhaps the decision 
variable that owners and policy makers will be most interested in mitigating. The fatality 
estimation carried out for the benchmark building provides a methodology for comparing this 
important value for various building designs, and enables informed decision making during the 
design process. 
The expected annual loss associated with fatalities caused by building earthquake damage 
is estimated by converting the expected annual number of fatalities into economic terms. 
Assuming the value of a human life is $3.5M, the fatality rate translates to an EAL due to 
fatalities of $3,500 to $5,600 for the code-conforming designs, and $79,800 for the non-code 
conforming design. Compared to the EAL due to repair costs of the code-conforming designs, 
which are on the order of $66,000, the monetary value associated with life loss is small, 
suggesting that the governing factor in this respect will be the maximum permissible life-safety 
risk deemed by the public (or its representative government) to be appropriate for buildings. 
Although the focus of this report is on one specific building, it can be used as a reference 
for other types of structures. This report is organized in such a way that the individual core 
chapters (4, 5, and 6) can be read independently. Chapter 1 provides background on the 
performance-based earthquake engineering (PBEE) approach. Chapter 2 presents the 
implementation of the PBEE methodology of the PEER framework, as applied to the benchmark 
building. Chapter 3 sets the stage for the choices of location and basic structural design. The subsequent core chapters focus on the hazard analysis (Chapter 4), the structural analysis 
(Chapter 5), and the damage and loss analyses (Chapter 6). Although the report is self-contained, 
readers interested in additional details can find them in the appendices.

An Assessment to Benchmark the Seismic Performance of a Code-Conforming Reinforced-Concrete Moment-Frame Building

The performance of four sections of a full-scale embankment constructed on soft soil is examined using a fully coupled and fully three-dimensional finite element analysis. The four sections had sim...

Three-dimensional finite element modelling of a full-scale geosynthetic-reinforced, pile-supported embankment

(NOTE: Most chapters include Questions and Practice Problems, Summary, and Comprehensive Questions and Practice Problems.) I. GENERAL PRINCIPLES. 1. Foundations in Civil Engineering. The Emergence of Modern Foundation Engineering. The Foundation Engineer. Uncertainties. Building Codes. Classification of Foundations. 2. Performance Requirements. Design Loads. Strength Requirements. Serviceability Requirements. Constructibility Requirements. Economic Requirements. 3. Soil Mechanics. Soil Composition. Soil Classification. Groundwater. Stress. Compressibility and Settlement. Strength. 4. Site Exploration and Characterization. Site Exploration. Laboratory Testing. In-Situ Testing. Synthesis of Field and Laboratory Data. Economics. II. SHALLOW FOUNDATION ANALYSIS AND DESIGN. 5. Shallow Foundations. Spread Footings. Mats. Bearing Pressure. 6. Shallow Foundations-Bearing Capacity. Bearing Capacity Failures. Bearing Capacity Analyses in Soil-General Shear Case. Groundwater Effects. Allowable Bearing Capacity. Selection of Soil Strength Parameters. Bearing Capacity Analyses-Local and Punching Shear Cases. Bearing Capacity on Layered Soils. Accuracy of Bearing Capacity Analyses. Bearing Spreadsheet. 7. Shallow Foundations-Settlement. Design Requirements. Overview of Settlement Analysis Methods. Induced Stresses beneath Shallow Foundations. Settlement Analyses Based on Laboratory Tests. Settlement Spreadsheet. Settlement Analyses Based on In-Situ Tests. Schmertmann Spreadsheet. Settlement of Foundations of Stratified Soils. Differential Settlement. Rate of Settlement. Accuracy of Settlement Predictions. 8. Spread Footings-Geotechnical Design. Design for Concentric Downward Loads. Design for Eccentric or Moment Loads. Design for Shear Loads. Design for Wind or Seismic Loads. Lightly-Loaded Footings. Footings on or near Slopes. Footings on Frozen Soils. Footings on Soils Prone to Scour. Footings on Rock. 9. Spread Footings-Structural Design. Selection of Materials. Basis for Design Methods. Design Loads. Minimum Cover Requirements and Standard Dimensions. Square Footings. Continuous Footings. Rectangular Footings. Combined Footings. Lightly-Loaded Footings. Connections with the Superstructure. 10. Mats. Rigid Methods. Nonrigid Methods. Determining the Coefficient of Subgrade Reaction. Structural Design. Settlement. Bearing Capacity. III. DEEP FOUNDATION ANALYSIS AND DESIGN. 11. Deep Foundations. Types of Deep Foundations and Definitions. Load Transfer. Piles. Drilled Shafts. Caissons. Mandrel-Driven Thin-Shells Filled with Concrete. Auger-Cast Piles. Pressure-Injected Footings. Pile-Supported and Pile-Enhanced Mats. Anchors. 12. Deep Foundations-Structural Integrity. Design Philosophy. Loads and Stresses. Piles. Drilled Shafts. Caps. Grade Beams. 13. Deep Foundations-Axial Load Capacity Based on Static Load Tests. Load Transfer. Conventional Load Tests. Interpretation of Test Results. Mobilization of Soil Resistance. Instrumented Load Tests. Osterberg Load Tests. When and Where to Use Full-Scale Load Tests. 14. Deep Foundations-Axial Load Capacity Based on Analytical Methods. Changes in Soil during Construction. Toe Bearing. Side Friction. Upward Load Capacity. Analyses Based on CPT Results. Group Effects. Settlement. 15. Deep Foundations-Axial Load Capacity Based on Dynamic Methods. Pile-Driving Formulas. Wave Equation Analyses. High-Strain Dynamic Testing. Low-Strain Dynamic Testing. Conclusions. 16. Deep Foundations-Lateral Load Capacity. Batter Piles. Response to Lateral Loads. Methods of Evaluating Lateral Load Capacity. p-y Method. Evans and Duncan's Method. Group Effects. Improving Lateral Capacity. 17. Deep Foundations-Design. Design Service Loads and Allowable Definitions. Subsurface Characterization. Foundation Type. Lateral Load Capacity. Axial Load Capacity. Driveability. Structural Design. Special Design Considerations. Verification and Redesign during Construction. Integrity Testing. IV. SPECIAL TOPICS. 18. Foundations on Weak and Compressible Soils. Deep Foundations. Shallow Foundations. Floating Foundations. Soil Improvement. 19. Foundations on Expansive Soils. The Nature, Origin, and Occurrence of Expansive Soils. Identifying, Testing, and Evaluating Expansive Soils. Estimating Potential Heave. Typical Structural Distress Patterns. Preventive Design and Construction Measures. Other Sources of Heave. 20. Foundations on Collapsible Soils. Origin and Occurrence of Collapsible Soils. Identification, Sampling, and Testing. Wetting Processes. Settlement Computations. Collapse in Deep Compacted Fills. Preventive and Remedial Measures. 21. Reliability-Based Design. Methods. LRFD for Structural Strength Requirements. LRFD for Geotechnical Strength Requirements. Serviceability Requirements. The Role of Engineering Judgement. Transition of LRFD. V. EARTH RETAINING STRUCTURE ANALYSIS AND DESIGN. 22. Earth-Retaining Structures. Externally Stabilized Systems. Internally Stabilized Systems. 23. Lateral Earth Pressures. Horizontal Stresses in Soil. Classical Lateral Earth Pressure Theories. Lateral Earth Pressures in Soils with c ...o and ... ...o 0. Equivalent Fluid Method. Presumptive Lateral Earth Pressures. Lateral Earth Pressures from Surcharge Loads. Groundwater Effects. Practical Application. 24. Cantilever Retaining Walls. External Stability. Retwall Spreadsheet. Internal Stability (Structural Design). Drainage and Waterproofing. Avoidance of Frost Heave Problems. 25. Sheet Pile Walls. Materials. Construction Methods and Equipment. Cantilever Sheet Pile Walls. Braced or Anchored Sheet Pile Walls. Appendix A: Unit Conversion Factors. Appendix B: Computer Software. References. Index.

Donald P. Coduto

Papers

Foundation Design: Principles and Practices