Experimental study on a single pile under horizontal elliptical/circular loading

The horizontal loading on the pile foundation is multidirectional in some practical problems. By use of the biaxial digital-controlled motion platform, model tests on a single pile under unidirectional, elliptical and circular loadings are performed. The bending moments along the pile in these tests are measured. From the test results, it is found that the characteristics of force-displacement curves under multidirectional loadings are apparently different from those under unidirectional loading. The maximum forces appear before the maximum displacements in the multidirectional tests, and these forces are smaller than those measured in the unidirectional tests. The difference between them increases with the aspect ratio of the loading path. It is also observed that the direction of force increment and that of displacement increment are noncoaxial under multidirectional loadings. The evolution of amplitude and direction of the force increment at the pile head is correlated to that of the coefficient of curvature of the loading paths.