Liquefaction Study Report: Recommended LRFD Guidelines for the Seismic Design of Highway Bridges

Keywords: Liquefaction. Hazards. Bridges. Liquefaction induced ground movement. Cascadia Subduction zone. New Madrid seismic zone. Return period.

Abstract: This report presents the results of the study of the effects of liquefaction and the associated hazards, lateral spreading and flow, which was undertaken in support of the NCHRP 12-49 efforts.  The purpose of this study was to investigate liquefaction hazard implications for the design of bridges from the perspective of real sites and real structures.  The study scope was limited to two sites, both in relatively high seismicity locations: one in Washington State (near the Cascadia subduction zone) and the other in Missouri (near the New Madrid seismic zone).  The investigation of the two sites and their respective bridges focused on the resulting response and design differences between the recommended ground shaking level and that corresponding to the current AASHTO Division I-A provisions.  The recommended provisions requiring a 100-year return period service-level earthquake was considered in this study.  Additional return period events were compared to further assess the implications, which contributed to synthesizing an overall approach for handling liquefaction-induced movements in the recommended design provisions.  There is an extensive use of figures and tables throughout the report. 

The nine appendices are provided in a separate PDF file, which contain detailed information for each site and each structure’s analysis and design.