Case Study of Parallel Bridges Affected by Liquefaction and Lateral Spreading

Abstract

AbstractTwo parallel adjacent river-crossing bridges performed differently in response to strong shaking (peak ground acceleration ∼0.27 g) and liquefaction-induced lateral spreading during the 2010 M 7.2 El Mayor-Cucapah earthquake. A railroad bridge span collapsed, whereas the adjacent highway bridge survived, with one support pier near the river having modest flexural cracking of cover concrete and a second settling approximately 50 cm. Cone penetration and geophysical test results are presented along with geotechnical and structural conditions evaluated from design documents. This investigation employed an equivalent-static beam-on-nonlinear-Winkler foundation analysis to accurately predict observed responses when liquefaction-compatible inertia demands were represented as spectral displacements that account for resistance from other bridge components. Pier columns for the surviving bridge effectively resisted lateral-spreading demands in part because of restraint provided by the superstructure. Coll...