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A novel experimental study of the dynamic and seismic response of a 2 m × 2 m in plan - 0.7 m in height groin vault model, involving 266 tests conducted on the shaking table of EQUALS laboratory, University of Bristol, UK, is reported. The experimental rig consists of blocks formed by a 3D-printed plastic skin to provide stiffness and strength, filled with mortar. Dry joints between the voussoirs are formed for ease of testing and vault reconstruction. No investigations of this kind and size have been attempted in the past. Two support boundary conditions involving four lateral confinement modes, leading to various vault configurations, were tested. White-noise, sinusoidal and earthquake motions were imposed in one horizontal direction, with progressively increasing amplitude and different frequencies, up to collapse. The model exhibited a strong non-linear behaviour, characterised by decreasing fundamental frequency and increasing damping with increasing table acceleration. Failure mechanisms and collapse accelerations were found to mainly depend on base restraint conditions. The SEBESMOVA3D project (SEeismic BEhaviour of Scaled MOdels of groin VAults made by 3D printers, https://sera-ta.eucentre.it/index.php/sera-ta-project-22/) was funded by European Union’s Horizon 2020 research and innovation programme SERA, under grant agreement No 730900.

Kinematic pile-soil interaction is investigated analytically through a Beam-on-Dynamic-Winkler-Foundation model. A cylindrical vertical pile in a homogeneous stratum, excited by vertically-propagating harmonic shear waves, is examined in the realm of linear viscoelastic material behaviour. New closed-form solutions for bending, displacements and rotations atop the pile, are derived for different boundary conditions at the head (free, fixed) and tip (free, hinged, fixed). Contrary to classical elastodynamic theory where pile response is governed by six dimensionless ratios, in the realm of the proposed Winkler analysis three dimensionless parameters suffice for describing pile-soil interaction: (1) a mechanical slenderness accounting for geometry and pile-soil stiffness contrast, (2) a dimensionless frequency (which is different from the classical elastodynamic parameter a0=ω d/Vs), and (3) soil material damping. With reference to kinematic pile bending, insight into the physics of the problem is gained through a rigorous superposition scheme involving an infinitely-long pile excited kinematically, and a pile of finite length excited by a concentrated force and a moment at the tip. It is shown that for long piles kinematic response is governed by a single dimensionless frequency parameter, leading to a unique master curve pertaining to all pile lengths and pile-soil stiffness ratios. © 2012 Elsevier Ltd. ispartof: SOIL DYNAMICS AND EARTHQUAKE ENGINEERING vol:44 pages:183-195 status: published

Pile foundations in seismic areas should be designed against two simultaneous actions arising from kinematic and inertial soil-structure interaction, which develop as a result of soil deformations in the vicinity of the pile and inertial loads imposed at the pile head. Due to the distinct nature of these phenomena, variable resistance patterns develop along the pile, which are affected in a different manner and extent by structural, seismological and geotechnical characteristics. A theoretical study is presented in this article, which aims at exploring the importance of pile diameter in resisting these actions. It is demonstrated that (a) for large diameter piles in soft soils, kinematic interaction dominates over inertial interaction; (b) a minimum and a maximum admissible diameter can be defined, beyond which a pile under a restraining cap will inevitably yield at the head i.e., even when highest material quality and/or amount of reinforcement are employed; (c) an optimal diameter can be defined that maximizes safety against bending failure. The role of diameter in seismically-induced bending is investigated for both steel and concrete piles in homogenous soils as well as soils with stiffness increasing proportionally with depth. A number of closed-form solutions are presented, by means of which a number of design issues are discussed.

Physical modeling has long been established as a powerful tool for studying seismic pile-soil-superstructure interaction. This chapter presents a series of 1-g shaking table tests aiming at clarifying fundamental aspects of kinematic and inertial interaction effects on pile-supported systems. Pile models in layered sand deposits were built in the laboratory and subjected to a wide set of earthquake motions. The piles were densely instrumented with accelerometers and strain gauges; therefore, earthquake response, including bending strains along their length, could be measured directly. Certain broad conclusions on kinematic and inertial SSI effects on this type of systems are drawn.