【正文】 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。 Loads to be reduced per table for angles less than 90o from vertical。 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。 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。 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)。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 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。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 Clearance not required for horizontal piping passing perpendicularly through successive studs or joists that form a wall/ceiling assembly。 Maximum vertical distance between 4way braces limited to 25 ft 2020 Braces and restraints identified as possible obstructions to sprinkler discharge 10. Sway Bracing Loads 1983 Sway bracing to withstand a force in tension or pression equivalent to not less than half the weight of waterfilled piping 1989 Assigned load table added. Alternative permitted for zone of influence method: For lateral braces all branch lines and mains within zone For longitudinal braces all mains within zone 1994 Multipliers permitted for horizontal force factor Fp = Wp where use of other force factors required or permitted by AHJ 1996 “When the horizontal force factor used exceeds Wp and the brace angle is less than 45o from vertical or when the horizontal force factor used exceeds Wp and the brace angle is less than 60o from vertical, the braces shall be arranged to resist the vertical reaction produced by the horizontal load” 1999 Assigned load table deleted 2020 Factor of Wp to be used to account for the added weight of fittings, valves and other devices 2020 – Table included of “Seismic Coefficients” to allow determination of horizontal seismic loads based on mapped values of short period response parameter SS。 Allowance for maximum spacing over 40 ft eliminated。 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。in and larger piping。 Clarification added that the structural ponents must be capable of carrying the added applied loads。 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, Natio