• Mylonakis, George
• Vardanega, Paul J.
• Katsiveli, Elpida
• Karamitros, Dimitris K.

Abstract

Footings subjected to dynamic loads are commonly designed under the simplifying assumption of linear or equivalent-linear soil behaviour. Even though this approach is simple to implement and, in some cases, could take advantage of available closed-form solutions, the outcomes remain a gross approximation. Although considerable research has been conducted for the case of high-amplitude footing vibrations, where uplift, slippage or even failure may occur, there remains a research gap for small to medium strain amplitudes, for which the behaviour is also non-linear. To address this problem, a numerical methodology is developed herein, for the analysis and design of shallow footings, while taking into consideration shear modulus degradation and hysteretic damping increase effects for the foundation subsoil. The analysis methodology is based on the implementation of the modified hyperbolic model as a user-defined formulation into the explicit finite difference code FLAC. Focus is then given on a rigid strip surface foundation subjected to a harmonic rocking motion, and results from preliminary analyses are presented in terms of the variation of the dynamic impedance with the dimensionless frequency of the<br/>excitation. Different excitation amplitudes are examined to demonstrate the effects of soil non-linearity, while strain rate effects are also investigated.

Topics

• impedance spectroscopy
• surface