Ricerc@Sapienza

In questo articolo si discutono i metodi per la valutazione della prestazione sismica dei pozzi
di fondazione di pile di ponti o viadotti di grande luce. Si tratta dapprima del ruolo dei pozzi
nei fenomeni di interazione terreno-struttura, descrivendo le peculiarità di tale tipo di
fondazione, confrontandole con quelle delle fondazioni superficiali, e presentando un esame
critico dei metodi maggiormente utilizzati nella pratica professionale. Successivamente,
vengono illustrati i principali risultati di uno studio parametrico effettuato mediante analisi

Safety of a foundation under seismic loading is strongly dependent on the inertial forces transmitted by the superstructure, exchanged with the surrounding soil and acting into the foundation itself. The latter contribution, typically neglected for shallow and pile foundations, should be considered for caisson foundations, much more massive and rigid than the foundation soil.

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.

This paper investigates the role of soil plasticity on the seismic performance of bridge piers founded on cylindrical caissons through a numerical study where the geometrical and mechanical properties of the caisson and the pier, as well as the weight of the deck, are varied. Numerical models of the soil-caisson-pier-deck systems are subjected to six real acceleration time histories differing in frequency content, strong-motion duration and intensity.