Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

Lateral load induced in piles (both long and short) under earthquake is a problem of serious complexity that has been plaguing professional engineers and researchers alike for quite some time. The practice in vogue is to ensure that fixed base shear of the column does not exceed static shear load capacity of the piles. Inertial and stiffness effects of pile are usually ignored in dynamic earthquake analysis. The present paper proposes a method where, based on modal response or time history analysis, load on short piles may be estimated under earthquake considering its stiffness, inertia, effect of material and geometric damping properties. The results are compared with the conventional methods. Effect of partial embedment, a situation that may develop under soil liquefaction during earthquake has also been derived. Pile loads are estimated for two cases: a) When the structure is a lumped mass system having infinite stiffness: like a machine foundation or a heavy short vessel supported directly on the pile cap. b) Superstructure has finite stiffness and mass like a frame (building /pipe rack etc) The paper assumes that for all cases when slenderness ratio L/r is less than 20 the pile behaves as short pile when failure or yielding of soil precedes the structural failure of the pile. The major advantage with this method is that it does not warrant a sophisticated software to be developed for the analysis. A simple spread sheet is sufficient to produce an accurate result.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

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

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Estimation of Lateral Load Capacity of Short Piles Under Earthquake Force

San Diego, California

Lateral load induced in piles (both long and short) under earthquake is a problem of serious complexity that has been plaguing professional engineers and researchers alike for quite some time. The practice in vogue is to ensure that fixed base shear of the column does not exceed static shear load capacity of the piles. Inertial and stiffness effects of pile are usually ignored in dynamic earthquake analysis. The present paper proposes a method where, based on modal response or time history analysis, load on short piles may be estimated under earthquake considering its stiffness, inertia, effect of material and geometric damping properties. The results are compared with the conventional methods. Effect of partial embedment, a situation that may develop under soil liquefaction during earthquake has also been derived. Pile loads are estimated for two cases: a) When the structure is a lumped mass system having infinite stiffness: like a machine foundation or a heavy short vessel supported directly on the pile cap. b) Superstructure has finite stiffness and mass like a frame (building /pipe rack etc) The paper assumes that for all cases when slenderness ratio L/r is less than 20 the pile behaves as short pile when failure or yielding of soil precedes the structural failure of the pile. The major advantage with this method is that it does not warrant a sophisticated software to be developed for the analysis. A simple spread sheet is sufficient to produce an accurate result.