Kinematic response analysis of piled foundations under seismic excitation

Abstract

This paper presents the results of an extensive parametric study on single piles and pile groups embedded in a two-layer subsoil profile, and is aimed to evaluate kinematic bending moments developing during earthquakes. A quasi three-dimensional finite element program has been used to perform dynamic analyses in the time domain. Piles have been considered as elastic beams, while the soil has been modelled using a linear elastic constitutive model. The aims of the paper are: (i) to evaluate kinematic bending moments in single piles and pile groups with dynamic analyses in the time domain, in different subsoil conditions; (ii) to review some existing design methods; (iii) to propose a simplified analysis procedure to evaluate maximum kinematic bending moments between two subsequent soil layers. The results of the dynamic analyses have shown that some of the simplified approaches provided in published literature tend to be conservative and can predict bending moments at the soil-layer interface with adequate accuracy only within certain depths of the soil layer interface. On the basis of the obtained results, a modified criterion to evaluate the transient peak bending moments at interfaces between layers is proposed.

Kinematic response of single piles for different boundary conditions: Analytical solutions and normalization schemes

“…Other contributions [17,24,25,26,27,28,29,30] have investigated the behaviour of piles in two-and multi-layer soil deposits under both harmonic and transient excitation.…”

1-g Experimental investigation of bi-layer soil response and kinematic pile bending

“…Besides pile slenderness, pile-soil stiffness and shear wave velocity contrast, this relation is based on the shear stress at the interface induced in the free-field by seismic motion. Maiorano et al [34] revised this expression introducing a dynamic coefficient β depending on the occurrence of resonance, and the transient peak soil shear strain γ 1 at the interface.…”

“…In recent years, pseudo-static methods, which constitute an essential tool in engineering practice, have been established for the seismic design of piles [29][30][31]. Similarly, simplified closed-form expressions for the evaluation of kinematic pile bending have been devoloped [7,[32][33][34][35][36].…”

Piles-Induced Filtering Action and Its Effect on the Seismic Response of Buildings

“…All the studies above and further studies on the subject [6][7][8][9][10][11] demonstrate that for motions that are rich in high frequency components, even practically flexible piles may not be able to follow the wavy movements of the free-field. On the other hand, if low-frequency compo-nents of the input motion are predominant, the scattered field is weak, and the support motion can be expected to be approximately equal to that of the free-field [12][13][14].…”