Soil-Foundation-Structure Interaction with Mobilization of Bearing Capacity: Experimental Study on Sand

Abstract

Recent studies have highlighted the beneficial role of foundation uplifting and the potential effectiveness of guiding the plastic hinge into the foundation soil by allowing full mobilization of bearing capacity during strong seismic shaking. With the inertia loading transmitted onto the superstructure being limited by the capacity of the foundation, this concept may provide an alternative method of in-ground seismic isolation: the so-called rocking isolation. Attempting to unravel the effectiveness of this alternative design method, this paper experimentally investigates the nonlinear response of a surface foundation on sand and its effect on the seismic performance of an idealized slender singledegree-of-freedom structure. Using a bridge pier as an illustrative prototype, three foundation design alternatives are considered, representing three levels of design conservatism. Their performance is investigated through static (monotonic and slow-cyclic pushover) loading, and reduced-scale shaking table testing. Rocking isolation may provide a valid alternative for the seismic protection of structures, providing encouraging evidence in favor of the innovative idea of moving foundation design toward a less conservative, even unconventional, treatment.

Static and cyclic rocking on sand: centrifuge versus reduced-scale 1gexperiments

“…04 rad), the footing (over an already denser soil) tends to uplift, although still eventually accumulates settlement. Similar trends have been noted by Drosos et al (2012) and Anastasopoulos et al (2013) in 1g experiments. But even for footings on saturated clay (under undrained conditions), Panagiotidou et al (2012) observed theoretically a cyclic overstrength, which was attributed to the beneficial role of P-ä effects acting in the opposite to the loading direction.…”

“…Several studies have explored the behaviour of foundations under lateral and combined loading, both theoretically (Nova & Montrasio, 1991;Butterfield & Gottardi, 1994;Paolucci, 1997;Bransby & Randolph, 1998;Martin & Houlsby, 2001;Gourvenec & Randolph, 2003;Chatzigogos et al, 2009) and experimentally (Negro et al, 2000;Gajan et al, 2005;Gajan & Kutter, 2008;Paolucci et al, 2008;Anastasopoulos et al, 2012Anastasopoulos et al, , 2013Deng et al, 2012;Drosos et al, 2012). Experimental studies have significantly contributed to the understanding of the rocking response of shallow foundations.…”

Effects of nonlinear soil–structure interaction on the seismic response of structure-TMD systems subjected to near-field earthquakes

“…Herein, value of 2 is assigned to this parameter in order to represent low aspect ratio which is more realistic. Furthermore, according to the nonlinear behavior of the supporting soil; another key non-dimensional parameter controls the interplay between uplifting and soil yielding is defined as the following ratio (Drosos et al 2012):…”

Balancing the Beneficial Contributions of Foundation Rocking and Structural Yielding to Improve Structural Seismic Resilience

“…More recently, researchers across the United States and Europe have undertaken a variety of 1-g and centrifuge tests coupled with numerical work to investigate the mobilization of soil-foundation capacity (see e.g. Rosebrook and Kutter [17]; Gajan and Kutter [8]; Anastasopoulos et al [1]; Deng et al [5]; Hakhamaneshi et al [10]; Gelagoti et al [9]; Drosos et al [6]). Since the centrifuge facility has the capability to create confining stress levels comparable with prototype conditions, the stress-dependent soil nonlinear behavior can thereby be reasonably captured.…”