ROTATION OF HIGH-LOAD MULTIROTATIONAL BRIDGE BEARINGS

High load multirotational (HLMR) bridge bearings are used to support l arge loads while accommodating rotations resulting from traffic loadin g, construction tolerances, thermal effects, and other deformations. P ot, disk, and spherical bearings qualify as HLMR bearings; a series of experiments were performed to evaluate their behavior, and to develop design recommendations. The experiments were performed on a specially designed rig that applies a constant compressive load, a constant she ar force, and a cyclic rotation. Sixteen tests were performed on pot b earings, four on spherical bearings, and two on disk bearings. The tes t results are summarized, and general observations on the bearing beha vior and design considerations are noted in this paper. Each bearing t ype has advantages and potential problems. Pot bearings are able to su pport large compressive loads, but their elastomer might leak and thei r sealing rings might suffer wear or damage. Disk bearings are suscept ible to uplift during rotation, which may limit their use in bearings with polytetrafluoroethylene (PTFE) sliding surfaces. Spherical bearin gs are able to sustain large rotations but require proper clearances, very smooth and accurate machining.