Task E1-2: Foundation Design for Liquefaction-Induced Displacements
Subject Area: Geotechnical and Foundation Engineering
|Principal Investigator and Institution
Geoffrey R. Martin, University of Southern California
The primary objective of this task is to develop practical analysis approaches that can be used to evaluate the ability of pile foundations in short- to medium-span bridges to accommodate displacement demands associated with liquefaction-induced lateral spreads. Emphasis is on piles or pile groups where the pile spacing does not lead to pile interaction under lateral loading (i.e., spacing greater than about five pile diameters).
During Research Years 1 and 2, this task developed: a case history database including available centrifuge model test results; simplified analysis methods for computing free field lateral spread deformations based on the Newmark approach; and a practical analysis approach to evaluate deformation demands on pile foundations. The deformation demand approach was incorporated into the recently completed seismic design specifications developed under NCHRP Project 12-49. A key component of this design methodology is the concept of allowing plastic hinge development in piles up to the ductility capacity, and incorporating the pile resistance to deformation in estimates of displacement demands related to ground deformation potential.
Results from Research Years 1 and 2 include the following:
During Research Year 3, the focus of the research will be on the completion of a final report, which includes detailed design guidelines. The scope of the work for Research Year 3 includes:
Although the numerical and modeling methods that are being used here are not new, they must be carefully employed in order to not induce errors into the simulations and results.
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