Contents
Preface
Table of conversion factors 1
Part I : Types of loads and types of soils
Chapter 1 : Applications
Shallow Foundations in Modem Construction 5
Common Types and Configurations of Buildings 5
Common Types and Configurations of Foundations 8
Common Soil Pressures and Settlements 10
Standard Test Specifications 12
Useful Approximations 12
Chapter 2 : Gravity Loads on Foundations
General Categories of Loads on Structures 15
Allowable Footing Pressures for Gravity Loads 15
Gravity Loads 16
Distribution of Gravity Loads to Foundations 20
Example Calculations of Gravity Loads on Footings 23
Combinations of Gravity Loads 26
Summary of Gravity Loads on Footings 27
Review Questions 27
Chapter 3 : Lateral Loads on Foundations
Types of Lateral Loads 31
Stability under Combined Loading 32
Wind Velocities and Stagnation Pressures 34
Shape Factors for Wind Loads 37
Calculation of Base Shear due to Wind 39
Overturning Moment due to Wind 39
Earthquake Loads on Structures 42
Seismic Risk Zones and Zone Factors 43
Seismic Response of Building Systems 45
Soil Profile Type for a Building Site 45
Seismic Coefficient for a Structure 45
Calculation of Base Shear due to Earthquake 48
Overturning Moment due to Earthquake 49
Effect of Lateral Load on Footings of Rigid Frames 53
Restoring Moment and Frictional Shear Resistance 54
Drift in a Rigid Frame 55
Summary of Foundation Loads on a Rigid Frame 56
Effect of Lateral Load on Foundations of Braced Frames 58
Drift in a Braced Frame 58
Restoring Moment and Frictional Shear Resistance 59
Allowable Soil Pressures for a Braced Frame 62
Summary of Foundation Loads for a Braced Frame 63
Load Combinations for Final Design 65
Applications in Determination of Design Loads 66
Review Questions 70
Chapter 4 : Classifications and Properties of Soils
Broad Soil Groupings 75
Response of a Soil to Foundation Loads 76
Geologic Origins of Soil 78
Soil Profiles and Soil Horizons 79
Grain Size and Distribution 81
Plasticity and Atterberg Limits 84
Consistency and Textural Classification of Soils 87
Engineering Classification of Soils 88
Index Properties of Soils 93
Review Questions 98
Part II : Response of a Soil Mass To Foundation Loads
Chapter 5 : Strength and Pressure Dispersion in Soils
Permeability, Effective Stress and Submergence 105
Measurement of the Shear Strength of Clays 108
Measurement of the Shear Strength of Sands 113
The Coulomb Equation for the Strength of Soils 122
Dispersion of Load into a Soil Mass 122
Approximate Dispersion of Load into a Soil Mass 127
Pressure Dispersion through Underlying Strata 129
At-Rest Pressures in a Soil Mass 132
In Situ Properties of Soils 135
Review Questions 136
Chapter 6 : Calculation of Allowable Pressures
Levels of Accuracy of the Failure Analysis 143
Ultimate Shear Failure in a Soil Mass 144
Allowable Bearing Strength of a Soil Mass 148
Corrections for Shape of Footings 158
Corrections for Depth of Founding 159
Corrections for Groundwater Level 160
Corrections for Lateral Loads 161
Common Factors of Safety in Soils 164
Use of a Reference Footing in Strength Calculations 166
Applications in Calculating Bearing Capacity 168
Review Questions 175
Chapter 7 : Settlement of Foundations in a Soil Mass
Consolidation and Settlement in Clays 181
Degree of Consolidation 183
Over consolidated Clay 186
The Consolidation Test for Clay Soils 188
Comparative Time-Consolidation Relationships 193
Fragmentation and Settlement in Sands 201
Review Questions 203
Chapter 8 : Calculation of Settlements
Differential Settlements 207
Reliability of Settlement Calculations 207
Use of a Reference Footing in Settlement Calculations 208
Settlement Calculations in Normally Consolidated Clays 213
Settlement Calculations in Over consolidated Clays 223
Settlement Calculations in Sands 234
Modulus of Subgrade Reaction 239
Comparison of Response of Clays and Sands to Load 240
Review Questions 241
Part III Design of Shallow Foundations on a Soil Mass
Chapter 9 : Effects of Soil-Structure Interaction
Summary of Allowable Soil Pressures 251
Estimated Pressure-Settlement Relationships 254
Effects of Structural Design on Foundation Design 256
Footings with Vertical Load Only 256
Effects of Column Moments on Footing Rotations 257
Effects of Footing Rotations on Soil Pressure 259
Generalization of Effects of Rotations 263
Attachment of Columns to Footings 266
Peak Pressure in Strength Calculations 268
Applications in Selecting Final Footing Sizes 269
Presumptive Bearing Pressures 277
Variations of Contact Pressures under a Footing 279
Review Questions 281
Chapter 10 : Comparative Selection of Footing Sizes
Interaction within a Group of Footings 285
Relative Settlements between Footings 286
Applications in Selecting Footing Sizes 287
Effects of Close Proximity 293
Effects of Unequal Loads 296
Effects of Intermixed Footing Types 298
Effects of Adjacent Excavations 302
Review Questions 304
Part IV : Related Topics in Foundation Systems
Chapter 11 : Other Topics in Foundation Design
Special Design Conditions 313
Combined Footings 313
Lateral Friction Loads on Footings 319
Foundations for Stucco or Decorative Masonry 322
Unreinforced Foundations 323
Rubble or Masonry Foundations 325
Treated Timber Foundations 326
Foundations on Expansive Clays 328
Review Questions 332
Chapter 12 : Field Tests and the Soils Report
Initiation of a Soils Investigation 335
Preliminary Assessment of Site 337
Scope of the Site Investigation 338
Field Sampling and Testing 348
Field Load-Settlement Tests 354
Common Laboratory Tests 357
The Soils Report 358
Review Questions 360
References 365
Index 369