【国外标准】 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.1.1 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.1.2 This specification covers the requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical).1.3 The requirements stated in this specification are the minima necessary for the manufacture of quality bearing devices. It may be necessary to increase these minimum values due to other design conditions.1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.1.6 The following safety hazards caveat pertains only to the test method portion, Section 7, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.