Structural Response to High Frequency Motion Released in Nonlinear Soil

Abstract

High frequency motion is often registered in experimental measurements in laminar boxes placed on shaking tables in centrifuge or 1-g laboratory tests when investigating soil free field response under sinusoidal input motions. The source of the high frequency motion is often attributed to inaccuracies of experimental setups. On the other hand, some numerical studies suggested physical explanations, due to soil complex mechanical behavior, such as general soil nonlinearity or dilation. The most recent numerical studies suggest initially another potential source of the high frequency motion in tested soil specimens, i.e. the hypothetical release of unloading elastic waves in the steady state response. Moreover, these studies show that soil-released high frequency motion can potentially impact structural response. This paper presents a brief example of a numerical study on dynamic soil-structure interaction analyzed under harmonic input motion of a single sinusoidal driving frequency. The soil is modelled using an advanced soil constitutive model to accurately represent soil cyclic behavior. The analyzed structure is shown to experience the motion of the driving frequency and the motion of high frequency in the steady state response. Importantly, the computed high frequency motion is not present at the specimen base and is apparently introduced into the dynamic system by soil nonlinearity.