Probabilistic Design Procedure that includes Pile-Pinning for Bridge Foundations undergoing Liquefaction-Induced Lateral Spreading

Abstract

Liquefaction-induced lateral spreading has caused significant damage to a number of bridges during past earthquakes. Ground displacements due to lateral spreading can damage the foundations, which may lead to collapse of the bridge superstructure. However, piles may actually “pin” the upper layer of soil that would normally spread atop the liquefied layer below it into the stronger soils below the liquefiable soil layer. This is called the “pile-pinning” effect. This design approach was incorporated in the MCEER/ATC-49-1 docu-ment. In this paper, this design procedure is summarized, and a slightly modified design procedure is then de-veloped to work within a probabilistic framework so that it is compatible with the concept of Performance-Based Earthquake Engineering (PBEE). Primary sources of uncertainty are considered with the intention of providing unbiased insight for making informed design decisions. The application of the proposed procedure is illustrated through a realistic design example.