United States Department of Transportation
i
Design procedure for Bridge Foundations Subject to Liquefaction-Induced Lateral Spreading
-
2017-04-01
[PDF-1.66 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Corporate Publisher:
-
Abstract:The response of piled bridge foundations to liquefaction-induced lateral soil deformation is an important design consideration in seismically active regions. Recent research and case history data suggest that three-dimensional deformation of the approach embankment can significantly influence the loads placed on the embedded foundations during a flow failure or lateral spreading event. For example, the 2010 Maule earthquake in Chile caused widespread lateral spreading in the soil surrounding the Mataquito River bridge, however, only insignificant structural damage was observed in the bridge itself. The discrepancy between the amount of soil deformation and structural damage suggests that design procedures for this load case that do not make adequate consideration for 3D soil deformation mechanisms may lead to overly conservative and expensive design solutions. In contrast, observed lateral spreading and damage near the Llacolén bridge was more relevant and resulted in the collapse of one of the approach sections. The Llacolén bridge approaches show lesser 3D effects on both sides of the bridge and therefore larger loads
on the structural components. In this work, finite element models of the Mataquito River and Llacolén bridges are created using the OpenSees computational framework to investigate possible reduction in foundation loads during lateral spreading implied by the observed structural damage at the sites. These models include beam on nonlinear Winkler foundation models, dynamic effective stress models of the bridge-foundation-soil system in plane strain, and 3D models of the bridge abutments, approach embankments, and surrounding soils. This numerical work seeks to frame load reduction mechanisms in the context of a
simplified analysis procedure for the lateral spreading load case. The results of the numerical models for the Mataquito and Llacolén bridges, along with a preliminary parameter study conducted using an independent set of 3D finite element models,
indicate that consideration for the 3D geometry of the bridge site and structure may result in tangible reductions in foundation bending demands and abutment displacements compared to those returned by a plane strain description of the problem or simplified analysis using 1D models. This analysis procedure is modified to better consider the findings of this work and it is recommended to use in the design of bridge foundations subjected to lateral spreading. Finally, an approach is proposed to estimate the reductions in abutment displacement and associated foundation bending demands for a given site geometry. The latter is based on results from a preliminary parametric study and would require further development and validation to use in practice.
17. Key Words
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
