Kinematic Bending Moments in Seismically Stressed Piles

Abstract

The report studies the kinematic deformation of a free-head and fixed-head pile embedded in layered soil. Such deformation arises from the passage through the soil surrounding the pile of vertical seismic waves, which impose on the pile lateral displacements and curvatures, thereby generating bending moments. A comprehensive parametric study is presented in this report aimed at developing: a) a fundamental understanding into the nature of the problem and b) simple design aids for inexpensively computing the peak bending moments in a pile, under an arbitrary seismic time history. It is demonstrated that peak kinematic moments during actual earthquakes can be correlated with the amplitudes of steady-state harmonic moments, and that simple formulae presented in the report would lead to satisfactory estimates of the largest peak bending moments in actual piles.<br>