Maria Giovanna Durante

Experimental Assessment of Seismic Pile-Soil Interaction

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.

Local site effects and incremental damage of buildings during the 2016 Central Italy earthquake sequence

The Central Italy earthquake sequence initiated on 24 August 2016 with a moment magnitude M6.1 event, followed by two earthquakes (M5.9 and M6.5) on 26 and 30 October, caused significant damage and loss of life in the town of Amatrice and other nearby villages and hamlets. The significance of this sequence led to a major international reconnaissance effort to thoroughly examine the effects of this disaster. Specifically, this paper presents evidences of strong local site effects (i.e., amplification of seismic waves because of stratigraphic and topographic effects that leads to damage concentration in certain areas). It also examines the damage patterns observed along the entire sequence of events in association with the spatial distribution of ground motion intensity with emphasis on the clearly distinct performance of reinforced concrete and masonry structures under multiple excitations. The paper concludes with a critical assessment of past retrofit measures efficiency and a series of lessons learned as per the behavior of structures to a sequence of strong earthquake events.

NUMERICAL SIMULATION OF SOIL-STRUCTURE INTERACTION: A PARAMETRIC STUDY

Soil Structure Interaction (SSI) is a complex phenomenon that may radically change the earthquake response of structural systems, as consequence of the variation of the natural frequency and the damping ratio. One of the most effective means for evaluating SSI is the use of physical models. In this study the physical model considered is formed by an oscillator founded on a group of piles embedded in a horizontally layered deposit of dry sand. The benchmark experimental campaign was carried out at the Bristol Laboratory for Advanced Dynamics Engineering (BLADE) at the University of Bristol (UK), financed by the Seismic Engineering Research Infrastructures for European Synergies (SERIES). An accurate parametric numerical study is performed and the results are discussed. The study investigates the effects of the dynamic properties of the oscillator on the period elongation and piles response. By means of advanced numerical analyses the outcomes of the present work provide insights into the quantitative evaluation of period elongation and the strength of inertial contribute to the bending moment at the pile head, when the system approaches resonance conditions. 3568 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 3568-3577

SOIL-PILE-STRUCTURE-INTERACTION: EXPERIMENTAL RESULTS AND NUMERICAL SIMULATIONS

The complex seismic soil-pile-structure interaction phenomenon is related to the interaction between foundation and structure under seismic and dynamic excitations. An ef- fective way to assess such phenomenon is to analyse the response of scaled physical model in 1-g or n-g devices. In this study some results selected from a comprehensive 1-g shaking table tests are reported and discussed. The extensive experimental campaign was carried out on the 3mx3m shaking table of the Bristol Laboratory for Advanced Dynamics Engineering (BLADE) at the University of Bristol (UK), within the framework of the Seismic Engineering Research Infrastructures for European Synergies (SERIES). The physical model comprises a pile group embedded in a by-layer soil deposit with different pile configurations. This paper focuses on the pile group response generated by the presence of a cantilever system (a single-degree-of- freedom, SDOF) connected at the top of the central pile considering no connection among the other pile heads. The selected input motions consist of a set of sinedwell excitations for SDOFs with different structural masses. The experimental data are used to validate an ad- vanced 2D difference element model using the FLAC2D code. The comparisons between the experimental and the numerical results are presented in terms of both envelope and time his- tories for the free-field and piles responses. The SDOF response is also assessed in terms of displacement time histories. Comparisons between the numerical and experimental test re- sults appear satisfactory; hence numerical approach can be used for further simulations of the soil-pile-structure interaction phenomena.