Abstract:
DFI Committee Project Fund Research findings by the DFI Drilled Shaft Technical Committee are presented on the topic of combining side and base resistance for soil bearing drilled shaft design. While it is known that both side and base resistance develop, it is common practice among many designers and owner agencies to only rely on one of these components. Many decision makers do this because of concerns about mobilizing the two components at compatible displacements or potential strain softening behavior. This research project involves evaluating a dataset of drilled shaft load tests with emphasis on the mobilization behavior of side and base resistance at compatible displacements, which is observed for the majority of the tests. The findings and conclusions of the research are presented and discussed in the context of axial design practices. The presentation also addresses situations where it may be appropriate to neglect side or base resistance and acknowledges that there may be non-technical factors that affect the decision to rely on both side and base resistance.