Surveys of the literature indicate that shell foundations are economical structural
elements which can be considered as the alternatives of flat foundations. However, the advantage
of shell elements in geotechnical engineering has not been explored yet, and these foundations are
still being treated as flat footings. The objective of this study is to investigate the geotechnical
behavior of two types of shell foundations under axial loading and present a comprehensive
formulation for bearing capacity of such foundations. For this purpose, a series of laboratory tests
were carried out on six types of shell foundations, namely conical and pyramidal shell foundations.
Different shell foundation geometries and Buckingham-Pi theorem were employed to formulate
the ultimate load capacity. Experimental results from previous investigations on shell footings
were used to verify the proposed formulations. Results of the present laboratory tests have
indicated that the pyramidal shell foundations show higher bearing capacities compared to their
corresponding conical ones and as the thickness of foundation increases, bearing capacity
decreases. Also, load bearing capacity equations of shell foundations determined from dimensional
analysis have shown a reasonably good agreement with experimental results.