Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

This paper presents the development and response of a numerical model for the representation of uplift and reattachment of shallow foundations using the Ruaumoko non-linear dynamic analysis software. Vertical loads carried by the foundation were used to control the rotational and horizontal characteristics, as the stiffness of all degrees of freedom must reduce as the footing progressively detaches from the underlying soil. This culminates in the representation of total uplift, where the foundation provides no stiffness in any degree of freedom until vertical loads become compressive again. Through extension of the capabilities of Ruaumoko, this response was able to be represented. The response of a simple elastic two bay frame structure with shallow foundations attached to the base of each column of the frame was evaluated when subjected to dynamic loads. Various approaches for the definition of the stiffness characteristics of the foundations are presented, as well as the methodology used to represent the effect of uplift. Uplift modeling was shown to have a significant effect on the shear and bending moment in the structural columns. If the point of detachment and reattachment of the foundation was at different horizontal and/or rotational displacements the result was residual horizontal and rotational displacements at the end of loading. This shift in displacement occurred in conjunction with a shift in shear and moment in the columns.

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

Effect of Uplift Modelling on the Seismic Response of Shallow Foundations

San Diego, California

This paper presents the development and response of a numerical model for the representation of uplift and reattachment of shallow foundations using the Ruaumoko non-linear dynamic analysis software. Vertical loads carried by the foundation were used to control the rotational and horizontal characteristics, as the stiffness of all degrees of freedom must reduce as the footing progressively detaches from the underlying soil. This culminates in the representation of total uplift, where the foundation provides no stiffness in any degree of freedom until vertical loads become compressive again. Through extension of the capabilities of Ruaumoko, this response was able to be represented. The response of a simple elastic two bay frame structure with shallow foundations attached to the base of each column of the frame was evaluated when subjected to dynamic loads. Various approaches for the definition of the stiffness characteristics of the foundations are presented, as well as the methodology used to represent the effect of uplift. Uplift modeling was shown to have a significant effect on the shear and bending moment in the structural columns. If the point of detachment and reattachment of the foundation was at different horizontal and/or rotational displacements the result was residual horizontal and rotational displacements at the end of loading. This shift in displacement occurred in conjunction with a shift in shear and moment in the columns.