## 2 Large Scale Experiment  
The research of non-linear soil-structure interaction under simulated seismic loading was conducted within the TRISEE research project. The project was carried out in the late 1990s and it comprised of several different large-scale experiments. The structure model included of a rigid steel column and a slab representing typical shallow footing. The column was used to introduce simulated seismic loading into the model. Through the column, horizontal force and overturning moment simulating the inertial loads were transmitted to foundations. The research programme included experiments conducted on dense and on loose sand with the relative density \(D_{r}\) of 85% and 45%, respectively. Ticino sand is a uniform coarse-to-medium silica sand with \(\text{D}_{50}\) = 0.55 mm, coefficient of uniformity, \(\text{C}_{\text{u}}\) = 1.6, specific gravity, \(\text{G}_{\text{s}}\) = 2.684, \(\text{e}_{\text{min}}\) = 0.579, \(\text{e}_{\text{max}}\) = 0.931 and constant volume frictional angle, \(\varphi_{cv}=35^{\circ}\). [PERSON]'s ratio equal to \(\
u\) = 0.30. The calculation of dynamic soil properties incorporated sand shear wave velocity taken from [12], \(v_{s}=220\ \frac{\text{m}}{\text{s}}\) for dense sand, and \(v_{s}=185\ \frac{\text{m}}{\text{s}}\) for the loose sand case. Square footing of 1.00 \(\times\) 1.00 m in plane, 0.20 m in thickness was embedded to the depth of 1.00 m so that the overburden pressure was simulated. The column of the model was modelled as 0.12 \(\times\) 0.12 m in cross section and 1.00 m in height. The model was made of steel with elasticity modulus equal to E = 210,000 \(\frac{\text{N}}{\text{mm}^{2}}\). A large sand box, measuring 4.60 \(\times\) 4.60 m in plan and 4.00 m in height (Figure 1) was constructed. Saturated Ticino sand was used to simulate the soil. The model founded on loosely built-in sand was loaded with 100 kN of vertical load, while the model founded on dense sand was loaded with a vertical force equal to 300 kN. In both cases, the vertical load applied was considerably lower than the soil load bearing capacity. The vertical load was introduced to the model using air cushions and a reaction beam while the horizontal cyclic load was applied at the top of the column using a hydraulic actuator. The vertical load was firstly applied to the model as it represents the weight of the superstructure. After the full vertical load was applied, cyclic load was introduced to the model as presented Figure 2. The cyclic load was applied to the model in three series, starting with small amplitude force-controlled cycles in Phase I, followed by application of earthquake-like time history loading in Phase II and finished with sinusoidal displacement cycles of increasing amplitude. The experimental model was examined by two groups of instruments. The first group of instruments embedded into the sand was used for the assessment of the initial soil conditions. Following sensors were placed in the soil: 9 small geophones which were used to measure saturation of the soil, 6 thermal and 6 electrical probes for the local check. The soil was tested by three cone penetration tests (CPT) performed by a standard cone with 35.7 mm in diameter. Moreover, body-wave velocities were measured during the different phases of sample preparation. A second group of instruments was used for observation of the foundation. Applied forces, horizontal and vertical displacements of the foundation, total and effective soil pressures underneath the foundation were monitored. The following sensors were installed: 11 load cells for horizontal and vertical stresses in the soil, 2 mini-piezometers for measuring the water pressure, 5 pressure cells underneath the foundation, 4 vertical displacement transducers at the corners of the foundation to measure settlements and rotations, 2 horizontal transducers in the foundation, a digital transducer to measure the horizontal displacement of the actuator, 2 load cells for the vertical force and 1 load cell (in the piston) for the horizontal force.