Physical and Numerical Modeling of Nonlinear Cyclic Load-Deformation Behavior of Shallow Foundations Supporting Rocking Shear Walls

A shear wall supported by a shallow foundation system is a commonly used seismic-force-resisting structural building system, yet there are many unresolved issues regarding their design and performance. One of the major changes in the traditional seismic design procedures adopted in the 1997 Federal Emergency Management Agency’s (FEMA) Building Retrofit NEHRP Guidelines was to allow mobilization of the ultimate capacity and rocking behavior of shallow foundations to reduce the ductility demands on structures. However, the uncertainty in soil properties, the absence of practical reliable foundation modeling techniques, and the resulting permanent settlement beneath the footing due to foundation rocking have hindered the use of nonlinear soilfoundation-structure interaction as a mechanism for reducing demands on the structure in practice. About sixty footings, representative of footings for building shear walls, were tested in a centrifuge under cyclic vertical (V), horizontal (H), and moment (M) loading; some were tested in slow cyclic loading while others were shaken using the shaking table on the centrifuge. Footing dimensions, depth of embedment, shear wall weight, soil