【正文】 ooks arranged to keep the pipe tight to the underside of the structural element 19. Sway Bracing Fasteners to Structure 1983 Pipe not to be fastened to building sections which will move differently 1987 Ctype clamps (with or without retaining straps) prohibited from brace attachment。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Another exception to permit tensiononly bracing systems when listed for this service and installed in accordance with listing limitation。 Lateral braces may act as longitudinal if within 24 in. of center line of piping braced longitudinally 1987 Longitudinal bracing required at maximum 80 ft. on center 1994 Omission of longitudinal braces permitted for pipes supported by rods less than 6 inches in length 1996 Deletion of 6inch rod exemption for longitudinal braces 1999 Longitudinal brace required within 40 ft of the end of a main 12. Sway Bracing Lateral Braces 1983 Last length of pipe at end of feed or cross main to be provided with lateral brace。 Exception added to permit pipe sleeves of nominal diameter 2 in. larger through 3189。 in. or larger 1994 For piping 2189。 in. or larger。in. pipe (4 in. larger for 4 inch and larger pipe)。 Appendix figures show lateral braces “about 40 ft.” 1985 Lateral bracing at maximum 40 ft. centers 1989 Maximum spacing to 50 ft. when building primary structural members exceed 40 ft. on center 1996 Distance between last brace and end of pipe limited to 20 ft. (25 ft where braces up to 50 ft. .)。 Threaded pipe used as part of a sway brace assembly to be not less than Schedule 30。 see Drake, . and Bachman, ., “NEHRP Provisions for Nonstructural Components,” ASCE Journal of Architectural Engineering, March 1996. 8. Voss, D., “The Importance of Adequate Seismic Design of Sprinkler Systems Following the 1987 Bay of Plenty Earthquake, 1987 Conference of the Institute of Fire Engineers, September 1987. 9. NFPA 13 – Installation of Sprinkler Systems, National Fire Protection Association, 1983, 1985, 1987, 1989, 1991, 1994, 1996, 1999, 2020 and 2020 editions. 。in and larger piping。 Allowance for maximum spacing over 40 ft eliminated。 Clearance not required for horizontal piping passing perpendicularly through successive studs or joists that form a wall/ceiling assembly。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Added applicability only “above ground level” 2020 – Expanded to “flexible fittings or flexible hose” and specified minimum capability of allowing movement to acmodate closing of the separation, opening of separation to twice normal size, and movement relative to the separation in the other two dimensions in an amount equal to the separation distance 8. Clearances 1983 Clearance through walls, floors, platforms and foundations 1 in. all sides through 3189。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Loads to be reduced per table for angles less than 90o from vertical。 Lock nuts and lips (on “C” or “Z” purlin) not permitted。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 see Clarified that length of hanger rod is measured between top of pipe and the point of attachment to the structure 15. Bracing/Restraint of Branch Lines 1987 Sway bracing not required for branch lines。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Swing joints assembled with flexible fittings on drops to racks over 3 in. 1987 Flexible couplings at the top of drops to hose lines (regardless of size)。 see NFPA 13 Earthquake Protection Submittee was in place at the time of the Loma Prieta and Northridge earthquakes in 1989 and 1994, and held public hearings in cooperation with the National Fire Sprinkler Association and the Society of Fire Protection Engineers following those events in order to evaluate how fire sprinkler systems performed during the earthquakes ands to develop suggestions for improvements to the protection criteria within the standard. In general, the performance of fire sprinkler systems in those earthquakes was judged to be good, with a strong correlationbetween observed failures and departures from the rules of NFPA 13. One area acknowledged to be in need of improvement was the interaction of sprinklers and ceilings。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Maximum vertical distance between 4way braces limited to 25 ft 2020 Braces and restraints identified as possi