Evidence of beneficial role of inclined piles: observations and summary of numerical analyses
Inclined piles find frequent use in foundations when substantial lateral stiffness is required. However for years, the seismic behaviour of inclined piles has been considered detrimental, and many codes require that such piles be avoided. However evidence has been accumulating that inclined piles may, at least in certain cases and if properly designed, be beneficial rather than detrimental both for the structure they support and the piles themselves. To gain deeper insight on the subject, the behaviour under seismic loading of inclined piles embedded in two idealized soil profiles, a homogeneous and a non-homogenous “Gibson” soil, is analyzed with 3D finite elements. It is shown that this role can be beneficial or detrimental depending on a number of factors, including the slenderness of the superstructure and the type of pile-to-cap connection.
Seismic behavior of batter piles
Several aspects of the seismic response of groups containing nonvertical piles are studied, including the lateral pile-head stiffnesses, the “kinematic” pile deformation, and the “inertial” soil-pile-structure response. A key goal is to explore the conditions under which the presence of batter piles is beneficial, indifferent, or detrimental. Parametric analyses are carried out using three-dimensional finite-element modeling, assuming elastic behavior of soil, piles, and superstructure.
Caisson Foundations subjected to normal fault
Dramatic failures have occurred in recent earthquakes due to the interplay of surface structures with outcropping fault ruptures, highlighting the need to account for fault induced loading in seismic design. Current research into the mechanisms of fault rupture–foundation–structure interaction has revealed a potentially favourable role of caissons in comparison to other foundation types. To argue for this statement and gain deeper insight of the response of caisson foundations under tectonic deformation, parametric analyses have been conducted with respect to the caisson foundation relative to the fault outcrop.
