Soil–pile–bridge Seismic Interaction: Kinematic and Inertial Effects. Part I: Soft Soil

Abstract

SUMMARYA substructuring method has been implemented for the seismic analysis of bridge piers founded on vertical piles and pile groups in multi-layered soil. The method reproduces semi-analytically both the kinematic and inertial soil-structure interaction, in a simple realistic way. Vertical S-wave propagation and the pile-to-pile interplay are treated with sufficient rigor, within the realm of equivalent-linear soil behaviour, while a variety of support conditions of the bridge deck on the pier can be studied with the method. Analyses are performed in both frequency and time domains, with the excitation specified at the surface of the outcropping ('elastic') rock. A parameter study explores the role of soil-structure interaction by elucidating, for typical bridge piers founded on soft soil, the key phenomena and parameters associated with the interplay between seismic excitation, soil profile, pile-foundation, and superstructure. Results illustrate the potential errors from ignoring: (i) the radiation damping generated from the oscillating piles, and (ii) the rotational component of motion at the head of the single pile or the pile-group cap. Results are obtained for accelerations of bridge deck and foundation points, as well as for bending moments along the piles.

Effect of Soil-Structure Interaction on the Seismic Response of an Instrumented Building During the Cephalonia, Greece Earthquake of 26-1-2014

“…For the analytical investigation of the phenomenon, two main methodologies have been developed, namely direct and substructure methods. In direct methods, a single numerical model (using finite elements, sometimes in combination with boundary elements) comprises the structure, its foundation and the surrounding soil, allowing for the analytical investigation of non-linear effects ( [3], [4], [5]). Substructure methods are suitable for only linear response (or linearised assumptions), and, being less computationally demanding, have been adopted by the current seismic codes.…”

Dynamic structure–soil–structure interaction between nearby piled buildings under seismic excitation by BEM–FEM model

“…Dynamic impedances and seismic response of piles and pile groups have been presented for several configurations and load conditions. These results can be used to address soil-structure interaction problems of pile supported structures making use of substructuring approaches as, for instance, in [40,41,42], though direct formulations have also been proposed and implemented, for example, for the dynamic analysis of bridge-pier systems, long-span bridges and multi-storey structures supported on piles, taking SSI into account [43,44,45]. A review of applications of the boundary element method (BEM) to the solution of both pile foundations and SSI elastodynamic problems, proposed during the period 1986-1996, was presented by Beskos [46].…”

Unified analysis of kinematic and inertial earthquake pile responses via the single-input response spectrum method

“…In the evaluation of the bending moment in a pile, both the effect of the forced displacement of a free-field ground (action 1) and the effect of the inertial force from a superstructure (action 2) as shown in Fig.1 have to be taken into account in an appropriate manner (for example [1][2][3][4][5][6][7][8][9][10][11]). However these two effects have different characteristics and it seems difficult to include these in a simple way keeping a reasonable accuracy.…”