SUMMARY A simplified three-step procedure is proposed for estimating the dynamic interaction between two vertical piles, subjected either to lateral pile-head loading or to vertically-propagating seismic S-waves. The starting point is the determination of the deflection profile of a solitary pile using any of the established methods available. Physically-motivated approximations are then introduced for the wave field radiating from an oscillating pile and for the effect of this field on an adjacent pile. The procedure is applied in this paper to a flexible pile embedded in a homogeneous stratum. To obtain analytical closed-form results for both pile-head and seismic-type loading pile-soil and soil-pile interaction are accounted for through a single dynamic Winkler model, with realistic frequency-dependent ‘springs’ and ‘dashpots’. Final- and intermediate-step results of the procedure compare favourably with those obtained using rigorous formulations for several pile group configurations. It is shown that, for a homogeneous stratum, pile-to-pile interaction effects are far more significant under head loading than under seismic excitation.

Dynamic pile‐soil‐pile interaction. Part II: Lateral and seismic response

The passage of seismic waves through the soil surrounding a pile imposes lateral displacements and curvatures on the pile, thereby generating ‘kinematic’ bending moments even in the absence of a su...

Kinematic pile bending during earthquakes: analysis and field measurements

SUMMARY A 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 suƒcient 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.

/pdf/soil-pile-bridge-seismic-interaction-kinematic-and-inertial-4ma2r1t466.pdf

Soil-pile-bridge seismic interaction : Kinematic and inertial effects. Part I: Soft soil

An elastic analysis is presented for the horizontal displacement and rotation of a laterally loaded pile group and the distribution of horizontal forces within the group. The interaction between two identical equally loaded piles is analyzed first, and the increases in displacement and rotation of the piles, in relation to the single pile values, are expressed in terms of interaction factors. Using these interaction factors, a method for calculating the displacement and rotation of a general pile group, based on the principle of superposition, is described. An examination of the behavior of square groups of piles reveals that the displacement, rotation, and load distribution in the group is largely influenced by the length-to-diameter ratio of the piles and the relative pile flexibility. It is also found that the displacement depends on the breadth of the group rather than the number of piles in the group. A reasonable measure of agreement is found between a limited number of reported measurements and theoretical predictions of group displacements.

Closure to “Behavior of Laterally Loaded Piles: II-Pile Groups”

This report describes a comprehensive experimental study to investigate cumulative damage in reinforced concrete circular bridge piers subjected to a series of earthquake excitations. Twelve identical quarter-scale bridge columns were tested. They were designed and fabricated in accordance with current AASHTO specifications. Testing was in two phases. Phase I testing consisted of benchmark tests to establish the monotonic force-deformation envelope and the energy capacity under standard cyclic loads; and constant amplitude tests to determine the low-cycle fatigue characteristics of the bridge column. Phase II testing was composed of a series of analytically predicted displacement amplitudes representing the bridge response to typical earthquakes. Test observations indicate two potential failure modes: low cycle fatigue of the longitudinal reinforcing bars; and confinement failure due to rupture of the confining spirals.

/pdf/cumulative-seismic-damage-of-reinforced-concrete-bridge-53xa6n65c0.pdf

Cumulative Seismic Damage of Reinforced Concrete Bridge Piers

Discussion of "Kinematic Seismic Response of Single Piles and Pile Groups"

This paper presents a comprehensive set of dimensionless graphs that could be readily utilized in practical applications A comparative study of these graphs leads to interesting conclusions that may contribute towards an improved appreciation of the nature of seismic pile-soil-pile interaction The graphs should be of practical value in determining the 'effective' seismic input motion at the base of structures, if the free-field motion is known The discussion of the study results focuses on elucidating the role of the key parameters, and aims at developing engineering insight into kinematic soil-pile and pile-pile interactions during earthquakes

Kinematic Seismic Response of Single Piles and Pile Groups

A comprehensive set of dimensionless graphs of complexvalued dynamic interaction factors versus frequency is presented for vertical, horizontal, and rocking harmonic excitation at the head of each ...

Dynamic interaction factors for floating pile groups

http://ssi.civil.ntua.gr/downloads/journals/1993-SDEE_Dynamic%20response%20of%20pile%20groups%20with%20different%20configurations.pdf

Dynamic response of pile groups with different configurations

/pdf/seismic-response-of-the-pile-foundation-of-ohba-ohashi-2xkfff5yrp.pdf

Ke Fan

Papers

Discussion of "Kinematic Seismic Response of Single Piles and Pile Groups"

Kinematic Seismic Response of Single Piles and Pile Groups

Dynamic interaction factors for floating pile groups

Dynamic response of pile groups with different configurations

Seismic Response of the Pile Foundation of Ohba-Ohashi Bridge