Precast AASHTO concrete bridge I-beams are often supported at the ends by elastomeric bearing pads. The bearing pad-bridge beam interface defines support boundary conditions that may affect the performance of the bridge. In this study, finite-element modeling was used to validate AASHTO bearing stiffness specifications. Stiffness characteristics of the Florida DOT bearing pads were theoretically determined under varying elastomer shear modulus values. Finite-element models of AASHTO Types III and V beams were subjected to simulated static truckloads. Vertical and horizontal spring elements simulating new bearing pads were incorporated at the ends of the beam models. A full section of a bridge was also modeled, and the results were compared with field tests. In general, the restraint effects of the bearing pads are beneficial to the performance of the beams and bridge. However, the beneficial effect is small for new bearing pads and more pronounced under a drastic increase in bearing stiffness due to aging and colder temperatures. This increase in bearing stiffness must be justified if the beneficial elements are to be utilized. Current Florida DOT bearing pads are serving the main purpose of their application--to provide minimum horizontal restraint force to the beams while allowing horizontal movement.


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  • Accession Number: 00797583
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 2 2000 12:00AM