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ASTM D5977-23
Standard Specification for High Load Rotational Spherical Bearings for Bridges and Structures
This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. The requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical) are discussed. The bearings are furnished in three types: fixed spherical bearing which is for rotation only, unidirectional sliding spherical bearing which is for rotation plus movement in one direction, and multi-directional sliding spherical bearing which is for rotation plus movement in all directions. The materials to be used in producing the bearings include: steel, stainless steel (flat sliding surface and convex surface), woven fabric polytetrafluoroethylene, and sheet polytetrafluoroethylene. The following different test methods shall be performed: proof load and rotation tests for fixed and expansion bearings, coefficient of friction test for expansion bearings only, PTFE (woven or sheet) bond test for expansion bearings only, and physical property test of both PTFEs for fixed and expansion bearings.
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ASTM International [astm]
