【正文】 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. 。 Exception added to permit powderdriven fasteners to attach braces where specially listed for use in earthquake areas 1999 Powderdriven fasteners prohibited from use with system hangers where horizontal force factor Fp exceeds Wp unless they are specially listed for such use NFPA 13 is generally updated on a threeyear cycle. As additional earthquake experience is obtained, more refinements will be made to the requirements of the standard to help ensure satisfactory performance in earthquakes. Although fire sprinkler systems are not expected to provide structural integrity to a building, they are expected to be able to carry out their function in any building that does maintain its structural integrity through an earthquake event. References 1. NBFU 13 – Installation of Sprinkler Systems, National Board of Fire Underwriters, 1947. 2. NFPA 13– Installation of Sprinkler Systems, National Fire Protection Association, 1951. 3. Fleming, R.., “Bracing for Earthquakes”, Sprinkler Quarterly, National Fire Sprinkler Association, Spring 1984. 4. Fleming, R.., “Lessons from the Loma Prieta Earthquake”, Sprinkler Quarterly, National Fire Sprinkler Association, Summer 1990. 5. Fleming, R.., “Sprinkler System Performance in the Northridge Earthquake,” Sprinkler Quarterly, National Fire Sprinkler Association, Spring 1994. 6. Fleming, R., Analysis of Fire Sprinkler Systems Performance in the Northridge Earthquake, NIST GCR 98736, January 1998. 2020 Structures Congress: New Horizons and Better Practices 169。 Ctype clamps prohibited from attaching braces 1996 Retaining straps used on Cclamps to be listed for use under seismic conditions or to be a steel strap not less than 16 gauge thickness and 1 in. wide, wrapped around beam flange not less than 1 inch。 Clarification added that the structural ponents must be capable of carrying the added applied loads。 Exception to permit lag screws/lag bolts where through bolts not practical due to thickness or inaccessibility。 see 1996 Connections to wood to be made using through bolts with washers on each end。 Fastener load tables added to appendix based on six orientation/angle conditions 1989 Fastener load tables moved from appendix to body of standard and expanded to nine orientation/angle conditions 1994 Powderdriven fasteners not permitted to attach braces unless specifically listed for this service 2020 Structures Congress: New Horizons and Better Practices 169。in and larger piping。 Threaded pipe used as part of a sway brace assembly to be not less than Schedule 30。 Where pipe, angles, flats or rods used as braces, exception to require listing of brace fittings and connections only。 see Maximum length load tables added to appendix based on three ranges of angle from vertical 1989 Maximum length and load tables moved from appendix to body of standard 1994 Allowable slenderness ratio increased to 300 1996 Sway brace assemblies required to be listed for a maximum allowable load。 For branch lines, restraint required within 2 ft of hangers at maximum 30ft intervals where upward or lateral movement of sprinklers would result in impact against building structure, equipment or finish materials 2020 Clarification of intent to prevent damage to sprinklers, not to prevent impact 17. Sway Bracing Brace Components 1983 Sway bracing to be designed to withstand a force in tension or pression 1985 For individual braces, the slenderness ratio l/r limited to 200 2020 Structures Congress: New Horizons and Better Practices 169。 Uhooks used to satisfy requirements for restraint required to have legs bent out 30o from vertical 2020 Except where branch lines are supported by rods less than 6 in. (150 mm) in length, restraint of all branch lines is required, with maximum distance between restraints ranging from 27 to 55 ft ( to m) depending on the size of the branch line and the force level。 Exception requires restraint of end sprinkler on line against excessive movement by wraparound Uhook or other approved means 1989 Second exception added to require lateral bracing for branch lines 2189。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Allowance for maximum spacing over 40 ft eliminated。 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