ABSTRACT
CONTENTS 3.1 Design Criteria .................................................................................................................... 88
3.1.1 Bearing Capacity Criterion.................................................................................... 88 3.1.2 Settlement Criterion................................................................................................ 89
3.2 Evaluation of Bearing Capacity........................................................................................ 89 3.2.1 Bearing Capacity Evaluation in Homogeneous Soil ......................................... 89 3.2.2 Net Ultimate Bearing Capacity............................................................................. 94 3.2.3 Foundations on Stiff Soil Overlying a Soft Clay Stratum ................................ 95 3.2.4 Foundations on Soft Soil Overlying a Hard Stratum ....................................... 96 3.2.5 Bearing Capacity in Soils Mixed in Layers ........................................................ 97 3.2.6 Bearing Capacity of Eccentric Footings .............................................................. 98 3.2.7 Bearing Capacity Using In Situ Test Data ........................................................ 100
3.2.7.1 Cone Penetration Test Data.................................................................. 100 3.2.7.2 Standard Penetration Test Data........................................................... 101 3.2.7.3 Plate Load Test Data ............................................................................. 101
3.2.8 Presumptive Load-Bearing Capacity................................................................. 102 3.3 Settlement Analysis .......................................................................................................... 102
3.3.1 Stress Distribution in Subsurface Soils Due to Foundation Loading........... 102 3.3.1.1 Analytical Methods ............................................................................... 102 3.3.1.2 Approximate Stress Distribution Method ......................................... 103
3.3.2 Settlement Computation Based on Plate Load Test Data .............................. 113 3.3.3 Computation of Settlement in Organic Soils.................................................... 113
3.4 Load and Resistance Factor Design Criteria ................................................................ 115 3.4.1 Load and Resistance Factor Design Philosophy.............................................. 116 3.4.2 Calibration by Fitting to ASD............................................................................. 116 3.4.3 Calibration by Reliability Theory....................................................................... 117
3.4.3.1 Variability of Soil Data........................................................................ 117 3.4.3.2 Normal Distribution ............................................................................ 119 3.4.3.3 Lognormal Distribution ...................................................................... 120 3.4.3.4 Estimation of Probabilities ................................................................. 120 3.4.3.5 Reliability of Design ............................................................................ 121 3.4.3.6 Reliability Index ................................................................................... 123 3.4.3.7 Resistance Statistics ............................................................................. 123 3.4.3.8 Load Statistics....................................................................................... 124 3.4.3.9 Determination of Resistance Factors ................................................ 124 3.4.3.10 Determination of the Simplified Resistance Factor........................ 126
3.5 Design of Footings to Withstand Vibrations................................................................ 130
3.5.2 Rocking Oscillations ............................................................................................. 135 3.5.3 Sliding Oscillations ............................................................................................... 136 3.5.4 Foundation Vibrations due to Rotating Masses .............................................. 138
3.6 Additional Examples........................................................................................................ 138 References ................................................................................................................................... 143
A shallow spread footing is designed for a building column in order to safely transmit the structural load to the ground without exceeding the bearing capacity of the ground and causing excessive settlements. The system that encompasses the footing and the ground influenced by the footing is generally referred to as the foundation.
