Simplified Constitutive Model for Simulation of Cyclic Response of Shallow Foundations: Validation against Laboratory Tests

Abstract

The nonlinear response of shallow foundations has been studied experimentally and analytically. However, the engineering community is not yet convinced of the applicability of such concepts in practice. A key prerequisite is the ability to realistically model such effects. Although several sophisticated constitutive models are readily available in the literature, their use in practice is limited, because (1) they typically require extensive soil testing for calibration; (2) as they are implemented in highly specialized numerical codes, they are usually restricted to simple superstructures; and (3) in most cases, they can only be applied by numerical analysis specialists. Attempting to overcome some of these difficulties, this paper develops a simplified but fairly comprehensive constitutive model for analysis of the cyclic response of shallow foundations. On the basis of a kinematic hardening constitutive model with Von Mises failure criterion (readily available in commercial finite element codes), the model is made pressure sensitive and capable of reproducing both the low-strain stiffness and the ultimate resistance of clays and sands. Encoded in ABAQUS through a simple user subroutine, the model is validated against (a) centrifuge tests of shallow footings on clay under cyclic loading and (b) large-scale tests of a square footing on dense and loose sand under cyclic loading, conducted in the European Laboratory for Structural Analysis for the TRISEE project. The performance of the model is shown to be quite satisfactory, and discrepancies between theory and experiment are discussed and potential culprits are identified. Requiring calibration of only two parameters and being easily implemented in commercial FE codes, the model is believed to provide an easily applicable engineering solution.

Experimental and Numerical Investigation of the Seismic Behavior of Rectangular Tunnels in Soft Soils

“…The model is embedded in ABAQUS and modified through a user subroutine, as presented by Anastasopoulos et al [22], to be applicable also for sands.…”

Seismic analysis of motorway bridges accounting for key structural components and nonlinear soil–structure interaction

“…The 8 latter is also modeled with hexahedral continuum elements. Nonlinear soil behavior is modeled with a kinematic hardening model, with a Von Mises failure criterion and associated flow rule [Anastasopoulos et al, 2011]. The evolution law of the model consists of a nonlinear kinematic hardening component, which describes the translation of the yield surface in the stress space, and an isotropic hardening component, which defines the size of the yield surface as a function of plastic deformation [Gerolymos & Gazetas, 2005].…”

Use of Ricker motions as an alternative to pushover testing

“…Details of this model can be found in the paper by Anastasopoulos et al (2011). Despite its lack of generality, the model has been shown to capture satisfactorily the nonlinear response of a shallow foundation on compliant soil (Anastasopoulos et al, 2011).…”

“…Details of this model can be found in the paper by Anastasopoulos et al (2011). Despite its lack of generality, the model has been shown to capture satisfactorily the nonlinear response of a shallow foundation on compliant soil (Anastasopoulos et al, 2011). Moreover, in an attempt to provide a more realistic representation of the pressuredependent sand behaviour, a user subroutine was encoded to provide variation of strength and stiffness properties with depth according to the relationships ϕ-σ v and E-z shown in Figure 5.…”