Physical characteristics of dynamic vertical–horizontal-rocking response of surface foundations on cohesionless soils

A fundamental experimental research programme on the dynamic behaviour of surface foundations on sand in general planar motion and the use of centrifuge modelling in soil–structure interaction studies is presented. Pursued with the dual purpose of extending the conventional formulation of dynamic test programmes as well as generating a physical database with sufficient parametric variations of the key aspects, an extensive experimental study to explore the dynamic soil–structure interaction problem in the small-amplitude regime is described. Through a comparison of the generated data with those from sequential vertical-centric and horizontal load tests, a novel hybrid-mode test concept by way of eccentric excitations is substantiated in terms of its economy and efficiency in capturing the force–response characteristics of the system. Synthesised in the frequency domain for direct qualitative and quantitative insights, multiple forced-response records of the foundation models on sand subjected to random vertical, horizontal and rocking excitations are summarised. As an illustration of the engineering relevance of the experimental database, a critical evaluation of the commonly used homogeneous half-space dynamic foundation solution pertaining to cohesionless soils is also provided.