Recent research shows that G0 applies to both static and dynamic properties, as well as to both undrained and drained loading conditions in geotechnical situations. Since the traditional penetration readings from the cone correspond to failure states, an entire stress-strainstrength curve can be derived at each depth from the SCPTu results. Applications are presented to illustrate how nonlinear stiffnesses are obtained and used in foundation case histories involving shallow footings and pile foundations.