The Ultimate Uplift Capacity of Foundations

TLDR

Further research is needed to evaluate the combined load effects and long‑term behavior of foundation uplift capacity. The study evaluates the ultimate uplift capacity of foundations, focusing on transmission tower footings. The authors examined model uplift tests and compared them with full‑scale tests, then derived a general theory using simplifying assumptions. The tests revealed a depth‑dependent failure mechanism, and the theory—after adjusting for shape and depth—provides a useful relationship for computing full‑scale uplift capacity, which can also be modified to account for group action.

Abstract

The ultimate uplift capacity of foundations with special reference to transmission tower footings is evaluated. A number of model uplift tests made by the authors and by others were studied and compared with full-scale tests. These tests showed a complex failure mechanism which varied with the depth of the foundation. Using simplifying assumptions a general theory was produced. It was shown that with suitable modification for shape and depth a useful relationship was available for computing the full-scale uplift capacity of foundations. It was further shown by model tests that the theory could be modified to take into account group action. Further research is required to evaluate the effect of combined loads and long-term effects.