Seismic Performance of Bridge Foundations in Liquefiable Soils

Abstract and project information last updated: 17 September 2012. Project updates are dated below.

AUTC
Project
Number
309010
Principal
Investigator
Zhaohui (Joey) Yang (UAA)
afzy@uaa.alaska.edu
Funding
Agency

US Department of Transportation (RITA)

Alaska Department of Transportation & Public Facilities

Project
Budget
88094
Start
Date
1 August 2009
Estimated
End Date
30 September 2012

Abstract

What happens to a bridge foundation during an earthquake if it is built on a frozen crust of ground that rests on a layer of liquefiable soil (soil that changes from behaving as a solid to behaving as a liquid during an earthquake)? How large are the loads generated by the interaction of frozen crust and foundation during a winter earthquake, and how should a designer deal with them? How can engineers make bridges safe and strong enough to withstand such forces of nature? These questions are unique to arctic areas such as Alaska, but there are no seismic analysis guidelines to account for how frozen-ground crust affects bridge foundations at a liquefiable site. This project provides the first quantitative evaluation of loads imposed on bridge foundations by a frozen crust with liquefaction and lateral spreading. Study results will improve seismic design of highway bridge foundations in areas of arctic conditions and seismic activity. Better seismic performance of Alaska’s bridges will increase transportation safety and reduce maintenance and reconstruction costs following a seismic event. In the first year of this two-year project, a sophisticated model capable of simulating soil liquefaction has been calibrated and validated with physical testing data. This validated model has been applied to simulate the response of a bridge pile foundation typical in Alaska, embedded in liquefiable soils with an unfrozen or a frozen crust. Preliminary results show that pile performance is very sensitive to crust conditions. The internal forces of the pile (for example, bending moment and shear force) change by about 50% when the crust freezes. These results demonstrate the great need to further this research. Numerical simulation seems insufficient in such determinations; researchers have proposed an experimental component to supplement this project. The funding request has been approved by AUTC and ADOT&PF (see Newly Funded Projects). In the experimental component, largescale shake-table experiments will be conducted in China in collaboration with the Harbin Institute of Technology. Test data, including soil responses and pile internal forces, will be collected to validate the computer simulation results. This project is the study focus of UAA graduate student Qiang Li, who has contributed to all project tasks. Li is working on his Master of Science degree in civil engineering.

Final Report

Seismic Performance and Design of Bridge Foundations in Liquefiable Ground with Frozen Crust
2 Jul 2013

Seismic Performance and Design of Bridge Foundation in Liquefiable Ground with a Frozen Crust
Zhaohui "Joey" Yang, Ph.D. Xiaoyu Zhang
309010.410015.Yang_.pdf

Related Project Activity

2 July 2013

Seismic Performance and Design of Bridge Foundations in Liquefiable Ground with Frozen Crust

by

309010.410015.Yang