Behavior of Axially and Eccentrically Loaded Trapezoidal Shell Footings Resting on a Granular Assembly

The objective of this paper is to investigate the behavior of strip shell footings subjected to axial and eccentric loads resting on a cylindrical steel rods assembly that simulates granular soil. An image processing analysis called particle image velocimetry (PIV) is used to obtain the displacement field around the footings. The bearing capacity and ultimate settlements of the footings are presented that show a linear variation with respect to the footing peak angle. The efficiency of eccentrically loaded shell footings is also discussed using settlement and rotation factors. Shell footings are proven to demonstrate better performance under eccentric loading in terms of settlement compared with axial loading cases, while a better performance is found at low eccentricities in terms of rotation. The PIV analysis provided the opportunity for a deeper comprehension of ground wedges beneath the footing and a comparison of results with analytical methods that validated the experimental results. Eventually, an eccentricity factor is proposed for the upper-bound solution to make it applicable for nonaxial loading cases.