ABSTRACT
ABSTRACT: A method is derived to determine the sliding resistance of shallow foundations in their joints to the subsoil to coupled actions of horizontal forces Hx, Hy and axial moments Mz acting around the vertical z-axis. To this end ideal friction conditions between foundation and subsoil as well as the kinematics of rigid bodies are assumed. The governing equations are presented and possible displacement fields within the foundation joints are illustrated. The resultant moment and the resultant forces of the sliding resistance are ascertained from the displacement field and the distributions of vertical stresses and friction coefficient by integrating over the compressed part of the foundation area. One possible distribution of the resistance is graphically presented by an interaction surface. The method is applied to footings of rectangular shape. Therefore the developed integral equations are elaborated under further assumptions and simplifications and analytically solved. The solution is illustrated by a H -Mz interaction diagram. Finally, examples show the application of the diagram and the influences of axial moments on the sliding resistance. Due to the interaction only small additional horizontal forces can be allowed, iffootings are already loaded by predominant axial moments and vice versa. This especially applies to small, compressed foundation areas, as the sliding resistance to axial moments (in contrast to the resistance to just horizontal forces) significantly depends on size and expansion of the compressed area.
