Pseudo-static interaction domains for caisson foundations

Caisson foundations are typically adopted for critical facilities, such as long-span bridges and viaducts, which are designed against intense and combined loading. Seismic-induced waves propagating within the soil deposit add a detrimental contribution, which reduces the bearing capacity of the soil-foundation system: this phenomenon, known as “kinematic effects”, is typically not considered in the standard design of caisson foundations. In this paper, pseudo-static IDs of caisson foundations are obtained through effective-stress Finite Element pushover analyses for different embedment ratios and initial loading factors and then validated against numerical and experimental results available in the literature. In the analyses, the hypothesis of a constant and uniform seismic coefficient kh is made: nonetheless, the assumption of a non-uniform distribution of the horizontal seismic coefficient is also considered via independent FE Limit Analysis. An analytical interpretation of the obtained IDs is finally provided, which may be successfully used for a preliminary design under seismic actions.