【正文】 ing。 Tensiononly bracing allowed if listed for the application 2020 Clarification that 4way bracing is required at the tops of risers exceeding 3 ft in length。 Seismic coefficient to be where no specified by the Authority Having Jurisdiction。 2020 ASCE Copyright ASCE 2020 Structures Congress 2020 Downloaded 06 Mar 2020 to . Redistribution subject to ASCE license or copyright。 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。 Longitudinal braces permitted to serve as lateral braces when within 24 in of center line of piping braced laterally 2020 – Table added to allow maximum load per brace based on spacing from 20 ft to 40 ft along with size and type of pipe。 Distance between last brace and end of pipe limited to 6 ft 13. Sway Bracing for Excessive Flexibility 1983 A sway brace required within 24 in. of flexible couplings used other than for earthquake protection 1989 A lateral brace required within 24 in. of every other (such) coupling, but not more than 40 ft. on center 14. Short Hanger Exception to Bracing 1983 Sway bracing may be omitted when hanger rods less than 6 in. long are used 1985 Moved to bee exception to requirement for lateral bracing 1994 Allowed for one edition to also apply to longitudinal braces (repealed in 1996) 2020 Structures Congress: New Horizons and Better Practices 169。 see Clarified that length of hanger rod is measured between top of pipe and the point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。 in. or larger 1991 Third exception added to require wraparound Uhook, lateral brace or 440lb. brace wire restraint at maximum 30 ft. intervals within 2 ft. of hanger where upward or lateral movement of sprinklers would result in impact against building structure, equipment or finish materials 1994 Sprigups exceeding 8 ft. in length to be restrained against lateral movement 1996 Sprigups 4 ft. or longer to be restrained against lateral movement 1999 Restraint clarified to be a lesser degree of resisting loads than bracing。 Additional hanger at minimum 45degree angle from vertical can be used as restraint if slenderness ratio does not exceed 300 16. Ceiling / Sprinkler Interaction 1983 Minimize or prevent pipe breakage 1991 Prevent pipe breakage。 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。 Another exception to permit tensiononly bracing systems when listed for this service and installed in accordance with listing limitation。 Appendix material added to remend sway brace members be continuous, but that where splices are necessary they should be designed and constructed to ensure that brace integrity is maintained 1999 Sample forms added to appendix to assist in brace calculations 18. UHooks as Sway Braces 1983 Utype hangers satisfy bracing requirements except longitudinal brace needed for 2189。 Utype hangers used as lateral braces to have legs bent at 10 degrees from vertical 1987 Utype hangers satisfy requirements for lateral sway bracing 1991 Wraparound Utype hangers permitted as lateral sway bracing provided legs are bent out 30 degrees from vertical and slenderness ratio criteria satisfied 1996 Allowance extended to Utype hooks 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。 Holes to be 1/16 in. greater than diameter of bolt。 Holes to be predrilled 1/8 in. smaller than maximum root diameter。 Appendix cautions added for expansion anchors in concrete 2020 – Allowable loads in fastener load tables reduced based on TIA to 2020 edition 20. Hanging and Piping Restrictions in Earthquake Areas 1987 Ctype clamps used to attach hangers must be equipped with retaining strap or other approved means to prevent movement。 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 copyri