ASTM C1858-17a(R2021) pdf free download

ASTM C1858-17a(R2021) pdf free download.Standard Practice for Design, Construction, and Material Requirements for Direct Hung Suspended T-bar Type Ceiling Systems Intended to Receive Gypsum Panel Products in Areas Subject to Earthquake Ground Motions
1. Scope
1.1 This practice covers the installation requirements of direct hung suspended t-bar type ceiling systems intended to receive gypsum panel products constructed as flat, single level, surrounded on all sides by a wall, bulk head, or soffit braced to the building structure to resist the effects of earthquake ground motions. 1.2 Ceiling assembly shall not be intended to support live loads. 1.3 This standard addresses ceiling systems with dead loads up to 10 lbs/ft 2 (48.8 kg/m 2 ). 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions—Terms shall be as defined in Terminology C11. 3.2 Definitions ofTerms Specific to This Standard: 3.2.1 counter sloping wire, n—opposing suspension wire intended to counteract the force of an out of plumb suspension wire and maintain alignment of the system. 3.2.2 cross runner, n—the secondary support members or cross beams of a mechanical ceiling suspension system trans- ferring ceiling load to the main runner. 3.2.3 diaphragm, n—horizontal system acting to transmit lateral forces to the vertical resisting elements. 3.2.4 direct hung ceiling, n—load carrying ceiling compo- nents that are fastened directly to structure.3.2.5 main runner, n—the primary or main beams (supports) of the ceiling suspension system. 3.2.6 t-bar ceiling, n—modular interlocking suspended ceil- ing system containing framing members with inverted T-shaped profiles.
4. Summary of Practice
4.1 This practice outlines the design and installation re- quirements of direct hung gypsum t-bar ceilings exempt from lateral bracing in areas subject to seismic activity.
5. Significance and Use
5.1 This practice provides a standardized installation proce- dure for ceilings designed and installed as a diaphragm. When installed according to this practice, these ceilings have suffi- cient strength to resist seismic forces without lateral force bracing.
7. Installation
7.1 The installation method described in this practice is limited to flat, single level designs surrounded on all sides by a wall, bulkhead, or soffit braced to the building structure to resist potential seismic forces imposed by the ceiling. 7.2 Securing Hanger to Structure: 7.2.1 Secure suspension wire to the building structure using hanger attachment device suitable to carry the tributary vertical load of the ceiling system. 7.2.2 Each suspension wire shall not hang more than one in six out of plumb unless a counter sloping wire or horizontal bracing is provided. See Fig. 1 for allowable counter sloping methods. 7.2.3 Locate vertical suspension wires no more than 24 in. from the perimeter on all main runners. 7.2.4 Local kinks or bends shall not be made in hanger as a means of leveling main runners. 7.2.5 In installations where the hanger wires are wrapped through main runners, the wire loops shall be tightly wrapped and sharply bent to prevent any vertical movement or rotation of the member within the loops. The wire shall be wrapped around itself a minimum of three full turns (360° each) within a 3-in [75 mm] length. For safety purposes, the bottom of the hanger wires shall either be cut close to the vertical portion of the wire or shall be bent upward parallel to the vertical portion of the hanger wire. 7.2.6 Hangers formed from galvanized sheet metal stock shall be suitable for suspending main runners from an existing structure provided that the hangers do not yield, twist or allow subsequent downward movement of the main runners due to imposed vertical ceiling loads.