Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

A new method was proposed in this study to evaluate the natural frequency of a pile-soil system under earthquake loading using a simple mass-spring model. The diagonal, 4x4, mass matrix in the model consisted of concentrated masses of a pile and a superstructure. The flexural stiffness of the pile and the spring stiffness between the pile and the soil were used to construct the stiffness matrix in the model. These two matrices were then input in the frequency equation for calculating the natural frequency of the pile system. The spring stiffness between the pile and the soil, which considerably influences the calculated natural frequency, was evaluated by using the coefficient of subgrade reaction modulus, the p-y curve, and the subsoil elastic modulus. The resulting natural frequencies were compared with those of 1-g shaking table tests. The comparison showed that the method of Reese (1974), which utilizes the coefficient of subgrade reaction modulus, and Yang’s (2009) dynamic p-y backbone curve method calculated the natural frequency of the pile-soil system most accurately. Their results were within 5% of the values obtained from the shaking table tests for the pile system in dry dense sand deposits.

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

Share

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

Natural Frequency Calculation of a Pile-Soil System in Dry Sand Under an Earthquake Loading

San Diego, California

A new method was proposed in this study to evaluate the natural frequency of a pile-soil system under earthquake loading using a simple mass-spring model. The diagonal, 4x4, mass matrix in the model consisted of concentrated masses of a pile and a superstructure. The flexural stiffness of the pile and the spring stiffness between the pile and the soil were used to construct the stiffness matrix in the model. These two matrices were then input in the frequency equation for calculating the natural frequency of the pile system. The spring stiffness between the pile and the soil, which considerably influences the calculated natural frequency, was evaluated by using the coefficient of subgrade reaction modulus, the p-y curve, and the subsoil elastic modulus. The resulting natural frequencies were compared with those of 1-g shaking table tests. The comparison showed that the method of Reese (1974), which utilizes the coefficient of subgrade reaction modulus, and Yang’s (2009) dynamic p-y backbone curve method calculated the natural frequency of the pile-soil system most accurately. Their results were within 5% of the values obtained from the shaking table tests for the pile system in dry dense sand deposits.