1、Designation: A 998/A 998M 08Standard Practice forStructural Design of Reinforcements for Fittings inFactoryMade Corrugated Steel Pipe for Sewers and OtherApplications1This standard is issued under the fixed designation A 998/A 998M; the number immediately following the designation indicates the year
2、of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the structural design of reinforce-
3、ment for fittings in factory-made, round corrugated steel pipe,conforming to Specifications A 760/A 760M or A 762/A 762M, for use as storm and sanitary sewers and other buriedapplications. This practice is for fittings on pipe installed in atrench or embankment and subjected to earth loads and livel
4、oads. It must be recognized that a buried corrugated pipe is acomposite structure made up of the steel ring and the soilenvelope, and both elements play a vital part. Both main andbranch pipe shall be designed in accordance with PracticeA 796/A 796M and installed in accordance with PracticeA 798/A 7
5、98M.1.2 This practice covers the structural design of reinforce-ment for fittings such as those for branch pipes. Refer toSection 5 for design limitations.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of
6、this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 The values stated in either inch-pound units or SI unitsshall be regarded separately as standard. The values stated ineach system are not exact equivalents;
7、 therefore, each systemmust be used independently of the other, without combiningvalues in any way. SI units are shown in brackets in the text forclarity, but they are the applicable values when the design is tobe performed using SI units.2. Referenced Documents2.1 ASTM Standards:2A 36/A 36M Specifi
8、cation for Carbon Structural SteelA 153/A 153M Specification for Zinc Coating (Hot-Dip) onIron and Steel HardwareA 307 Specification for Carbon Steel Bolts and Studs, 60000 PSI Tensile StrengthA 760/A 760M Specification for Corrugated Steel Pipe,Metallic-Coated for Sewers and DrainsA 762/A 762M Spec
9、ification for Corrugated Steel Pipe,Polymer Precoated for Sewers and DrainsA 796/A 796M Practice for Structural Design of Corru-gated Steel Pipe, Pipe-Arches, and Arches for Storm andSanitary Sewers and Other Buried ApplicationsA 798/A 798M Practice for Installing Factory-Made Corru-gated Steel Pipe
10、 for Sewers and Other ApplicationsA 902 Terminology Relating to Metallic Coated Steel Prod-uctsA 929/A 929M Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel PipeF 568M Specification for Carbon andAlloy Steel ExternallyThreaded Metric Fasteners (Metric)2.2 AA
11、SHTO Standard:3Standard Specifications for Highway BridgesLRFD Bridge Design Specifications2.3 American Railway Engineering and Maintenance-of-Way Association:AREMA Manual42.4 Society of Automotive Engineers:1This practice is under the jurisdiction of ASTM Committee A05 on Metallic-Coated Iron and S
12、teel Products and is the direct responsibility of SubcommitteeA05.17 on Corrugated Steel Pipe Specifications.Current edition approved May 1, 2008. Published June 2008. Originallyapproved in 1998. Last previous edition approved in 1998 as A 998/A 998M -98(2003).2For referenced ASTM standards, visit t
13、he ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. C
14、apitol St., NW, Suite 249, Washington, DC 20001.4Available from American Railway Engineering and Maintenance-of-WayAssociation (AREMA), 8201 Corporate Drive, Suite 1125, Landover, MD207852230.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
15、States.J978, Steel Self-Drilling Tapping Screws53. Terminology3.1 For definitions of general terms used in this standard,refer to Terminology A 902.3.2 Definitions of Terms Specific to This Standard:3.2.1 branch pipecorrugated pipe with a diameter smallerthan or equal to that of the main pipe, carry
16、ing a portion of theflow and connected to the main pipe through a fitting welded inplace.3.2.2 fittingssections of main pipe fabricated to accom-modate branch pipes or manhole pipes.3.2.3 main pipecorrugated pipe carrying the primary flow.3.2.4 reinforcementsheets, bars, or structural membersconnect
17、ed to the main pipe to strengthen a fitting.4. Symbols4.1 The symbols used in this practice have the followingsignificance:a = distance of saddle plate extension onto main pipe,in. mm.Ali= incremental required min cross section area of eachlongitudinal reinforcement, in2/ft mm2/m.Arc= required minim
18、um cross section area of each cir-cumferential reinforcement, in2mm2.Arcs= cross section area of circumferential reinforcementactually selected, in2mm2.Arl= required min cross section area of each longitudinalreinforcement, in2mm2.Arls= cross section area of longitudinal reinforcementactually select
19、ed, in2mm2.d = branch diameter, in. mm.db= nominal bolt diameter, in. mm.de= effective branch diameter, in. mm.dm= maximum branch pipe diameter for which no cir-cumferential reinforcement is required in. mm.ds= nominal screw diameter, in. mm.D = main pipe diameter, in. mm.H = depth of fill above top
20、 of pipe, ft m.He= equivalent depth of fill, ft m.Hnlr= fill height for which no longitudinal reinforcementis required, ft m.L = total length of each longitudinal reinforcement, in.mm.Lw= length of weld, in. mm.LL = live load pressure (see Practice A 796/A 796M),lbf/ft2kPa.Nc= minimum total number o
21、f fasteners required toattach each circumferential reinforcement.Nl= minimum total number of fasteners required toattach each longitudinal reinforcement.q = allowable load for each fastener, lbf N.tnp= bare steel thickness of pipe, in. mm.tnr= bare steel thickness of reinforcement in contact withpip
22、e, in. mm.tx= bare steel thickness of pipe or reinforcement,whichever is less, in. mm.w = unit force derived from 1 ft31 m3 of fill materialabove the pipe, lbf/ft3kN/m3. When actual fillmaterial is not known use 120 lbf/ft319 kN/m3.a = acute angle between main and branch pipe, degrees.5. Basis of De
23、sign5.1 Reinforcement requirements depend upon pipe diam-eter, pipe wall profile, pipe wall thickness, density of fillmaterial, height of cover, and live load. Main pipes withintersecting branch pipes shall be investigated in accordancewith Section 6 to determine whether reinforcement is required.If
24、 reinforcement is required, it shall be designed in accordancewith the provisions of Sections 9 and 10, unless one of thealternatives specified in Section 7 is met. Fittings in main pipeswith a diameter less than 48 in. 1200 mm, subject to thelimitations of 5.2-5.6, do not require reinforcement.5.2
25、This practice does not apply to cases where there aretwo branch pipes on opposite sides of the main pipe, each witha diameter greater than 0.75D, unless the longitudinal distancebetween the centerlines of the branches measured along themain pipe is greater than D.5.3 This practice is limited to pipe
26、 with a live load that canbe described and quantified such as AASHTO H20 or HS20and AREMA E80.5.4 Reinforcement design shall be based on an equivalentdepth of fill (He) that accounts for both earth load and live load(LL) as follows:He5LL 1 wH120FHe5LL 1 wH19G(1)This practice is limited to pipe with
27、He# 30 ft 9 m.5.5 Reinforcement design shall be based on an effectivebranch diameter (de) determined for the branch angle (a)asfollows:de5dsina(2)Calculated values of deshall be rounded up to the next 6 in.150 mm increment for design calculations. The value of demust not exceed 1.16D.5.6 This practi
28、ce is further limited to a from 30 to 90,inclusive.5.7 This practice applies where the branch pipe is welded tothe main pipe and has a specified thickness based on therequirements of A 796/A 796M.5.8 This practice does not include the possible effects ofdragdown loads on vertical risers (manholes) s
29、uch as caused bysettlement of deep fills.6. Need for Reinforcement6.1 The need for both longitudinal and circumferentialreinforcement as illustrated in Fig. 1 shall be considered.6.2 Longitudinal reinforcement needs shall be determinedfrom Tables 1-48 as applicable for the main pipe diameter and5Ava
30、ilable from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001.A 998/A 998M 082wall profile under consideration.6These tables list, for indi-cated branch pipe diameters, values of fill height, Hnlr, forwhich no longitudinal reinforcement is required. If He# Hnlr,no
31、 longitudinal reinforcement is required; otherwise, longitu-dinal reinforcement shall be designed in accordance withSection 9. For main pipe diameters not included in Tables 1-48,interpolation shall be permitted. Fittings for branch pipes witha diameter less than shown in Tables 1-48, subject to the
32、limitations of 5.2-5.6, do not require longitudinal reinforce-ment.6.3 Circumferential reinforcement needs shall be deter-mined from Tables 49-54 as applicable for the wall profileunder consideration.6These tables list, for indicated main pipediameters and wall thicknesses, the maximum branch pipedi
33、ameters, dm, for which no circumferential reinforcement isrequired. If de# dm, no circumferential reinforcement isrequired; otherwise, circumferential reinforcement shall bedesigned in accordance with Section 10. Branch diameters arelisted for equivalent depths of fill (He) of 10, 20, and 30 ft 3,6,
34、 and 9 m. Use the 10 ft 3 m column for 1 # He# 10 ft 1# He# 3 m. For other Henot listed, interpolate between thevalues listed.6The diameter-thickness combinations listed in the tables do not necessarilymeet the requirements of A 796.FIG. 1 Schematic of ReinforcementsFIG. 2 Schematic of Saddle PlateF
35、IG. 3 Schematic of Beam Type ReinforcementTABLE 1 Requirements for Longitudinal Reinforcement ofFittings in 48 in. Diameter Main Pipe with 2-23 by12 in.CorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinforcement is Required,Hnlr, and Incremental Longitudinal Reinforcement Area, Ali0.0
36、64 in.Thick0.079 in.Thick0.109 in.Thick0.138 in.Thick0.168 in.ThickMain Pipe Main Pipe Main Pipe Main Pipe Main PipeBranch Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali,Dia., in ft in.2/ft ft in.2/ft ft in.2/ft ft in.2/ft ft in.2/ft24 37.4 0.05 48.2 0.04 69.1 0.0430 27.5 0.07 36.3 0.06 53.2
37、0.0536 22.2 0.10 29.6 0.09 39.2 0.07 50.0 0.0642 17.9 0.13 21.6 0.11 28.9 0.09 37.0 0.07 45.0 0.0648 13.8 0.18 16.6 0.15 22.0 0.12 28.0 0.09 34.0 0.07ABranch pipe of any profile with specified thickness as required by A 796/A 796M.TABLE 2 Requirements for Longitudinal Reinforcement ofFittings in 120
38、0 mm Diameter Main Pipe with 68 by 13 mmCorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinforcement is Required,Hnlr, and Incremental Longitudinal Reinforcement Area, Ali1.63 mmThick2.01 mmThick2.77 mmThick3.51 mmThick4.27 mmThickMain Pipe Main Pipe Main Pipe Main Pipe Main PipeBranch
39、 Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali,Dia., mm m mm2/m m mm2/m m mm2/m m mm2/m m mm2/m600 11.4 106. 14.7 85. 21.1 85.750 8.4 148. 11.1 127. 16.2 106.900 6.8 212. 9.0 191. 11.9 148. 15.2 127. 18.6 106.1050 5.5 275. 6.6 233. 8.8 191. 11.3 148. 13.7 127.1200 4.2 381. 5.1 318. 6.7 254.
40、8.5 191. 10.4 148.ABranch pipe of any profile with specified thickness as required by A 796/A 796M.TABLE 3 Requirements for Longitudinal Reinforcement ofFittings in 60 in. Diameter Main Pipe with 2-23 by12 in.CorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinforcement is Required,Hnlr
41、, and Incremental Longitudinal Reinforcement Area, Ali0.064 in.Thick0.079 in.Thick0.109 in.Thick0.138 in.Thick0.168 in.ThickMain Pipe Main Pipe Main Pipe Main Pipe Main PipeBranch Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali,Dia., in. ft in.2/ft ft in.2/ft ft in.2/ft ft in.2/ft ft in.2/ft24
42、 29.9 0.06 38.6 0.05 55.3 0.0430 22.0 0.09 29.0 0.08 42.6 0.0636 17.7 0.12 23.6 0.10 31.4 0.09 40.0 0.0842 14.3 0.16 17.3 0.14 23.1 0.11 29.0 0.09 35.0 0.0748 11.0 0.21 13.3 0.18 17.6 0.14 22.0 0.10 27.0 0.0854 8.7 0.27 10.5 0.22 14.0 0.17 18.0 0.12 22.0 0.1060 7.0 0.33 8.5 0.28 11.3 0.21 14.0 0.15
43、17.0 0.12ABranch pipe of any profile with specified thickness as required by A 796/A 796M.A 998/A 998M 0837. Alternatives to Providing Reinforcement7.1 As an alternative to providing required longitudinal orcircumferential reinforcement, or both, an increase in thethickness of the main pipe shall be
44、 permitted. The increasedthickness must be such that the pipe does not require reinforce-ment when checked in accordance with 6.2, if longitudinalreinforcement is omitted, and 6.3, if circumferential reinforce-ment is omitted.7.2 As a second alternative to providing required longitudi-nal or circumf
45、erential reinforcement, or both, it is permissibleto provide a saddle plate as illustrated in Fig. 2 with a thicknessselected from Tables 55 and 56. Saddle plates that act asreinforcement must be of the same material and wall profile asthe main pipe and must extend onto the main pipe on all sidesfro
46、m the branch pipe a distance, a,ofde/4 or 6 in. 150 mm,whichever is greater. The saddle plate must be continuouslywelded to a stub length of the branch pipe. The stub must havea full uncut section at least 12 in. 300 mm long. The saddleplate must be connected to the main pipe with sufficientfastener
47、s (welds, bolts, or screws) so that there are no largegaps and so that it will act together with the main pipe.TABLE 4 Requirements for Longitudinal Reinforcement ofFittings in 1500 mm Diameter Main Pipe with 68 by 13 mmCorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinforcement is Re
48、quired,Hnlr, and Incremental Longitudinal Reinforcement Area, Ali1.63 mmThick2.01 mmThick2.77 mmThick3.51 mmThick4.27 mmThickMain Pipe Main Pipe Main Pipe Main Pipe Main PipeBranch Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr, Ali,Dia., mm m mm2/m m mm2/m m mm2/m m mm2/m m mm2/m600 9.l 127 11.8
49、106 16.9 85750 6.7 191 8.8 169 13.0 127900 5.4 254 7.2 212 9.6 191 12.2 1691050 4.4 339 5.3 296 7.0 233 8.8 191 10.7 1481200 3.4 445 4.1 381 5.4 296 6.7 212 8.2 1691350 2.7 572 3.2 466 4.3 360 5.5 254 6.7 2121500 2.1 699 2.6 593 3.4 445 4.3 318 5.2 254ABranch pipe of any profile with specified thickness as required by A 796/A 796M.TABLE 5 Requirements for Longitudinal Reinforcement ofFittings in 72 in. Diameter Main Pipe with 2-23 by12 in.CorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinfo
