Ricerc@Sapienza

Tuned Mass Dampers (TMDs) are aimed at mitigating vibrations of a structure under seismic or wind excitation by tuning the characteristics of the device to control specific resonance frequencies of the structure. However, the vibration modes of a structure can be considerably altered by the interaction with soil, leading to a loss of efficiency of the device. This paper shows the preliminary results of a study aimed at formulating a methodology for the design of TMDs accounting for soil-structure interaction.

The railway station Flaminio, currently located at street level, will be relocated underground to connect the railway with the existing line A metro station. This paper describes the technical and technological solutions adopted in the design to minimize tunnelling-induced effects on the surface and, in particular, on an old masonry building, whose foundations are very close to the roof of the new three-tunnel station.

In this paper, a simplified procedure for the evaluation of the seismic performance of bridge piers founded on caissons subjected to strong ground motions is outlined. To this end, the up-per-bound semi-empirical relationships proposed in [1] are considered for the estimation of the seismic performance, expressed in terms of the maximum and permanent values of the deck drift ratio attained during and at the end of the seismic event.

In this paper, the influence of inelastic soil behaviour on the seismic performance of bridge piers supported by caisson foundations is assessed. The results of an extensive parametric study, performed assuming a linear elastic and an elastic-plastic soil behaviour, are compared, showing the strong influence of the inelastic soil response. The geometrical properties of caissons and piers are varied; the systems are subjected to seismic records capable of mobilising the shear strength of the soil.

Substructure method is widely used to evaluate the seismic performance of caisson foundations supporting bridge piers subjected to strong ground motions, mainly because of its simplicity. However, the strongly-simplifying assumption of linear viscous-elastic behaviour for the foundation soil limits its applicability to flexible systems subjected to low-intensity earthquakes, for which irreversible strains and pore water pressure build-up are not anticipated.

The Leaning Bell Tower of Pisa has been included in the list of the World Heritage Sites by UNESCO since 1987. Over the last 20 years, the Tower has successfully undergone a number of interventions to reduce its inclination. The Tower has also been equipped with a sensor network for seismic monitoring.

The Leaning Bell Tower of Pisa (Italy) – built between 1173 and 1370 – is included within the list of the World Heritage Sites by UNESCO since 1987. In the past years, the Tower and the underlying soil have undergone many interventions in the attempt to reduce and stop definitely its inclination. The Tower was also equipped with a sensor network in-tended for seismic monitoring, which recorded the dynamic response of the monument un-der some far-field earthquakes.

The Tower of Pisa survived several strong earthquakes undamaged over the last 650 years, despite its leaning and limited strength and ductility. No credible explanation for its remarkable seismic performance exists to date. A reassessment of this unique case history in light of new seismological, geological, structural, and geotechnical information is reported, aiming to address this question.

An experimental study has been carried out to investigate the effects of soil partial saturation on the behaviour of laterally loaded piles. The proposed study has been conducted by means of centrifuge tests at 100×g, where a single vertical pile has been subjected to a combination of static horizontal load and bending moment. The study has been conducted on a silty soil characterized with laboratory testing under saturated and unsaturated conditions. During flight, two different positions of water table have been explored.

This note presents the preliminary outcomes of a numerical investigation on the influence of soil partial saturation on the behaviour of laterally loaded piles. The modified Cam clay model extended to unsaturated conditions and formulated in terms of Bishop’s effective stress has been used to analyse the results of centrifuge tests designed to address this topic. The model, calibrated on laboratory tests, well reproduces the main aspects of the soil-pile interaction.