Alternative Title

Investigation of Seismic Soil-Footing Interaction by Large Scale Cyclic Tests and Anlaytical Models [sic]

Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

Recent experimental and analytical research on seismic behavior of shallow foundations is illustrated. The most significant results on the seismic bearing capacity of footings with pseudo-static approaches are reviewed first, including an analytical formula recently proposed for the new version of the “seismic” Eurocode 8. Afterwards, we present the salient experimental results of large-scale cyclic tests of a shallow foundation model (1m x 1m in plan) resting on a large volume of sand, with relative densities 45% and 85%, discussing them in detail. Under earthquake-like cyclic loading, with peak values close to the pseudo-static failure limit, significant permanent settlement and rocking were observed, approaching serviceability limit states in low-density soil conditions. A series of displacement cycles of increasing amplitude was subsequently applied, up to the ultimate capacity of the soil-foundation system. Although the experimental cyclic bearing capacity is much higher than that predicted by pseudo-static approaches, this advantage is offset by the occurrence of large permanent deformations that may lead the structure to collapse. Finally, a recent theoretical method for performing simple nonlinear dynamic soil-structure interaction analyses is reviewed, and applied to estimating the reduction of response spectrum ordinates in strong earthquakes. Reductions up to 30%-50% were found for spectral accelerations exceeding 0.4g.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Investigation of Seismic Soil-Footing Interaction by Large Scale Cyclic Tests and Analytical Models

San Diego, California

Recent experimental and analytical research on seismic behavior of shallow foundations is illustrated. The most significant results on the seismic bearing capacity of footings with pseudo-static approaches are reviewed first, including an analytical formula recently proposed for the new version of the “seismic” Eurocode 8. Afterwards, we present the salient experimental results of large-scale cyclic tests of a shallow foundation model (1m x 1m in plan) resting on a large volume of sand, with relative densities 45% and 85%, discussing them in detail. Under earthquake-like cyclic loading, with peak values close to the pseudo-static failure limit, significant permanent settlement and rocking were observed, approaching serviceability limit states in low-density soil conditions. A series of displacement cycles of increasing amplitude was subsequently applied, up to the ultimate capacity of the soil-foundation system. Although the experimental cyclic bearing capacity is much higher than that predicted by pseudo-static approaches, this advantage is offset by the occurrence of large permanent deformations that may lead the structure to collapse. Finally, a recent theoretical method for performing simple nonlinear dynamic soil-structure interaction analyses is reviewed, and applied to estimating the reduction of response spectrum ordinates in strong earthquakes. Reductions up to 30%-50% were found for spectral accelerations exceeding 0.4g.