Overturning Forces at Bridge Abutments and the Interaction of Horizontal Forces from Adjacent Roadways (FHWA-OK-17-03)

Abstract

ODOT is experiencing a number of problems related to the interactions between bridge abutments and adjacent roadways. These problems include expansion joints closing, roller support bearings tilting, and beams pushing against abutment backwalls. Design, construction, repair, and maintenance guidelines to alleviate adverse effects of interactions between ODOT bridge abutments (non-integral), bridge decks, and adjacent roadways are developed based on field observations, instrumentation of selected bridges, and computer simulations. Three bridges were selected for detailed instrumentation including measurements of strains at various locations of approach slabs, approach pavements, and bridge decks; relative displacements between approach slabs and approach pavements; relative tilt of the abutment backwalls and pier caps; and temperatures at various locations over a period of seven years. At two of these bridges, measurements were also made before and after repairs. In addition, strains near newly installed expansion joints on five other bridges were monitored. The observed distresses were classified into two main categories. One related to rigid approach pavements exerting pressures on the bridges and the other related to lateral displacements from tall approach embankments early in the life of the bridges. A 4-inch pressure relief joint installed on an approach pavement was found to relieve bridge stresses caused by a rigid approach pavement. Providing expansion joints on rigid approach pavements at regular intervals, maintaining expansion joints on bridges and pavements, and geotechnical analyses to calculate lateral displacements from tall approach embankments during the design phase are some of the recommendations made to prevent or remediate the observed distresses.