The British Geotechnical Association (BGA) is the principal
association for geotechnical engineers in the United Kingdom.

BGA 59th Rankine Lecture

BGA Meeting
  • 20.03.2019
  • 17:30 - 19:30
  • The Great Hall, Sherfield Building, Imperial College London, Exhibition Road, SW7 2AZ
  • Organiser: British Geotechnical Association
  • Download to Calendar
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The 59th Rankine Lecture

will be delivered by

Dr George Gazetas

of the National Technical University of Athens, Greece

on

Benefits of Unconventional Seismic Foundation Design

Wednesday 20th March 2019 at 5.30pm

The Great Hall, Sherfield Building, Imperial College London, Exhibition Road, SW7 2AZ

This event is free to attend and advance registration is not required.

The British Geotechnical Association (BGA) is pleased to announce that the 59th Rankine Lecture will be given by Professor George Gazetas of the National Technical University of Athens, Greece. A flyer can be downloaded here.

The Rankine Lecture is widely viewed as the most prestigious of the invited lectures in geotechnics. It commemorates William John Macquorn Rankine, Professor of Civil Engineering at Glasgow University, who was one of the first engineers in the UK to make a significant contribution to soil mechanics. He is best known for his theory for the earth pressure on retaining walls.

The Rankine Dinner is held after the lecture - details and the process to apply for Dinner tickets can be found here. The Dinner is usually oversubscribed and interested parties are recommended to apply early.

Speaker Biography

George Gazetas has been Professor of Geotechnical Engineering at the National Technical University of Athens for 30 years, following an academic career in the US, where he taught at SUNY-Buffalo, Rensselaer (RPI), and Case Western Reserve University. His main research interests have focused on the dynamic response of footings, piles and caissons; the seismic response of earth dams and quay-walls; soil amplification of seismic waves; and soil–structure interaction problems. Much of his research has been inspired by observations after destructive earthquakes. An active writer and teacher, he has been a consultant on a variety of (mainly dynamic) geotechnical problems. The recipient of prestigious awards for his research contributions, he has given the Coulomb (2009) and Ishihara (2013) Lectures, and received the Excellence in University Teaching Award in Greece (2015).

Abstract

Current seismic geotechnical practice has embraced concepts inspired by pseudo-static thinking and force-based methodologies. The result is often over-designed foundations that, in addition to being uneconomical and difficult to implement, might unexpectedly lead to poor technical performance of foundation–structure systems.

The lecture will address the benefits of drastically changing the established philosophy in seismic foundation design. Emphasis will be given to “foundation rocking and soil failure”of tall slender structures, the foundations of which we deliberately under-designed to ensure that during strong shaking substantially nonlinear and inelastic soil-foundation interaction takes place ― uplifting of footing from the supporting soil, along with mobilisation of bearing-capacity failure mechanisms in the soil. Thanks to thekinematicnature of seismic shaking, allowing such unconventional response limits the accelerations transmitted up into the super-structure. Hence it reduces the inertia loading which “returns back” onto the foundation in the form of overturning moments and shear forces. Owing to its cyclicnature, seismic response generates a significant amount of damping in the soil, while exceedance of the ultimate capacity acts (only) momentarily and alternatingly. The two phenomena contribute towards decreased response intensity and acceptable levels of residual deformations (displacements and rotations). Deformations are further diminished by the beneficial contribution of gravity to re-centering of the foundation.

Physical experiments, analyses, and field observations, involving a variety of structural systems and foundations, will illustrate the technical advantages of such unconventional designs. Analysis of two historic seismic case histories, involving failure of bridge piers and overturning of buildings, will further demonstrate the potential benefits (as well as the limitations) of this new paradigm in seismic soil–foundation–structure interaction.

The lecture will be broadcast live and the link made available via the BGA website just before the event.


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