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Two geotechnical centrifuge tests were designed to elicit the influence of soil-foundation-structure interaction (SFSI) and structure-soil-structure interaction (SSSI) effects on the seismic demands of an inelastic frame structure founded on individual spread footings. Four experimental cases were considered: (1) SFSI of an individual inelastic frame structure (baseline case); (2) in-plane SSSI between the frame structure and a large elastic wall structure designed to respond predominately in a rocking mode; (3) anti-plane SSSI between the frame and wall structures; and (4) combined in-plane and anti-plane SSSI between the frame structure and two wall structures. Results from Cases 1, 2, and 4 are analyzed considering 13 demand parameters. The peak seismic demands from the baseline case are compared to the peak demands from the SSSI cases to elicit the impacts of building adjacency. The number of earthquake motions that resulted in increases or decreases in the seismic demands in the frame structure are tracked for the SSSI cases. For these tests, SSSI consistently results in increased peak foundation moment and foundation base shear demands, regardless of the geometric layout of the structures. These increases propagate throughout the superstructure, resulting in increases in moment, shear and curvature ductility demands in the structural components. SSSI effects are observed to be most significant for low-to-moderate intensity earthquake motions, suggesting that particular consideration should be given to the likelihood of SSSI for highly probable earthquakes. [ABSTRACT FROM AUTHOR]

A fully instrumented experiment was conducted to investigate the soil-structure interaction of single short, stiff laterally loaded piles. A hollow steel pipe pile with a diameter of 102 mm, a thickness of 6.4 mm, and a length of 1.524 m was installed in well-graded sand and subjected to increasing lateral load. The pile and surrounding soil were fully instrumented using advanced sensors, including flexible shape acceleration arrays, thin tactile pressure sheets, and in-soil null pressure sensors. The sensors attached to the pile were used to develop the compressive soil-pile interaction pressures and the lateral displacement along the pile length. The tactile pressure sheet sensors provided the soil-pile interaction compressive pressures on the circumference of the pile at a specific depth and along the length of the pile. The measured soil-pile interaction compressive pressures combined with the measured lateral displacement along the pile length were used to develop the soil-pile interaction force-displacement relationships ( curves) using direct measurements. In addition, the in-soil null pressure sensor measurements were used to develop the distribution of horizontal stress changes around the pile as the lateral pile displacement increased. When appropriate, the measured results were compared with data and methods available in the literature. [ABSTRACT FROM AUTHOR]