TY - JOUR

T1 - Simplified discrete systems for dynamic analysis of structures on footings and piles

AU - Maravas, Andreas

AU - Mylonakis, George

AU - Karabalis, Dimitris L.

PY - 2014/6/1

Y1 - 2014/6/1

N2 - A simplified discrete system in the form of a simple oscillator is developed to simulate the dynamic behavior of a structure founded through footings or piles on compliant ground, under harmonic excitation. Exact analytical expressions for the fundamental natural period and the corresponding damping coefficients of the above system are derived, as function of geometry and the frequency-dependent foundation impedances. In an effort to quantify the coupling between swaying and rocking oscillations in embedded foundations such as piles, the reference system is translated from the footing-soil interface to the depth where the resultant soil reaction is applied, to ensure a diagonal impedance matrix. The resulting eccentricity is a measure of the coupling effect between the two oscillation modes. The amounts of radiation damping generated from a single pile and a surface footing are evaluated. In order to compare the damping of a structure on a surface footing and a pile, the notion of static and geometric equivalence is introduced. It is shown that a pile may generate significantly higher radiation damping than an equivalent footing, thus acting as an elementary protective system against seismic action.

AB - A simplified discrete system in the form of a simple oscillator is developed to simulate the dynamic behavior of a structure founded through footings or piles on compliant ground, under harmonic excitation. Exact analytical expressions for the fundamental natural period and the corresponding damping coefficients of the above system are derived, as function of geometry and the frequency-dependent foundation impedances. In an effort to quantify the coupling between swaying and rocking oscillations in embedded foundations such as piles, the reference system is translated from the footing-soil interface to the depth where the resultant soil reaction is applied, to ensure a diagonal impedance matrix. The resulting eccentricity is a measure of the coupling effect between the two oscillation modes. The amounts of radiation damping generated from a single pile and a surface footing are evaluated. In order to compare the damping of a structure on a surface footing and a pile, the notion of static and geometric equivalence is introduced. It is shown that a pile may generate significantly higher radiation damping than an equivalent footing, thus acting as an elementary protective system against seismic action.

KW - Footings

KW - Foundation impedance

KW - Natural period

KW - Piles

KW - Radiation damping

KW - Soil-structure interaction

UR - http://www.scopus.com/inward/record.url?scp=84894098018&partnerID=8YFLogxK

U2 - 10.1016/j.soildyn.2014.01.016

DO - 10.1016/j.soildyn.2014.01.016

M3 - Article (Academic Journal)

AN - SCOPUS:84894098018

VL - 61-62

SP - 29

EP - 39

JO - Soil Dynamics and Earthquake Engineering

JF - Soil Dynamics and Earthquake Engineering

SN - 0267-7261

ER -