PACIFIC EARTHQUAKE ENGINEERING RESEARCH CENTER Evaluation of Collapse and Non-Collapse of Parallel Bridges Affected by Liquefaction and Lateral Spreading

................................................................................................................................. iii ACKNOWLEDGMENTS .............................................................................................................v CONTENTS................................................................................................................................. vii LIST OF FIGURES ..................................................................................................................... ix LIST OF TABLES ..................................................................................................................... xiii 1 INTRODUCTION..............................................................................................................1 2 SITE DESCRIPTION AND INVESTIGATION ............................................................3 2.1 Regional and Local Geology .................................................................................3 2.2 Site Topography and Surface Conditions ............................................................5 2.3 Subsurface Conditions ...........................................................................................8 2.3.1 Previous Subsurface Investigations by Others .............................................8 2.3.2 Current Subsurface Investigation .................................................................9 2.3.3 Interpretation of Vs Profile .........................................................................12 2.4 Bridge Details .......................................................................................................15 2.4.1 Highway Bridge (HWB) ............................................................................15 2.4.2 Railroad Bridge (RRB) ..............................................................................19 2.5 April 4, 2010, M 7.2 El Mayor-Cucapah Earthquake ......................................19 2.6 Observed Damage ................................................................................................22 2.6.1 Ground Deformation ..................................................................................22 2.6.2 Structural Damage .....................................................................................24 3 ANALYSIS .......................................................................................................................27 3.1 Soil Properties ......................................................................................................29 3.2 Lateral Spreading Displacement ........................................................................35 3.3 Modeling of Structural Elements .......................................................................37 3.3.1 Moment-Curvature Analysis ......................................................................40 3.3.2 Elastomeric Bearings and Shear Tabs ........................................................42 3.4 Inertial Loads from Superstructure ...................................................................45 3.4.1 Spectral Displacement Method ..................................................................46