1、Designation: A 998/A 998M 98 (Reapproved 2003)Standard 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
2、indicates the yearof 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the structural d
3、esign of reinforce-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 ea
4、rth loads and liveloads. 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 wit
5、h PracticeA 798/A 798M.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 theresponsibil
6、ity of the user of 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
7、 exact equivalents; 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:
8、2A 36/A 36M Specification for Carbon Structural SteelA 153 Specification for Zinc Coating (Hot-Dip) on Iron andSteel HardwareA 307 Specification for Carbon Steel Bolts and Studs,60 000 psi Tensile StrengthA 760/A 760M Specification for Corrugated Steel Pipe,Metallic-Coated for Sewers and DrainsA 762
9、/A 762M Specification for Corrugated Steel Pipe,Polymer Precoated for Sewers and DrainsA 796/A 796M Practice for the 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-
10、gated Steel Pipe for Sewers and Other ApplicationsA 902 Terminology Related 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 and Alloy Steel ExternallyThreaded Metric Fastener
11、s2.2 AASHTO Standard:Standard Specifications for Highway Bridges32.3 Society of Automotive Engineers:J978, Steel Self-Drilling Tapping Screws43. 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 b
12、ranch pipecorrugated pipe with a diameter smallerthan or equal to that of the main pipe, carrying 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 pipecorrugate
13、d pipe carrying the primary flow.1This practice is under the jurisdiction of ASTM Committee A05 on MetallicCoated Iron and Steel Products and is the direct responsibility of SubcommitteeA05.17 on Corrugated Steel Pipe Specifications.Current edition approved October 1, 2003. Published November 2003.
14、Originallyapproved in 1998. Last previous edition approved in 1998 as A 998/A 998M - 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summa
15、ry page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.4Available from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001.1Copyright ASTM Interna
16、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.4 reinforcementsheets, bars, or structural membersconnected to the main pipe to strengthen a fitting.4. Symbols4.1 The symbols used in this practice have the followingsignificance:a = distance of saddle p
17、late extension onto main pipe,in. mm.Ali= incremental required min cross section area of eachlongitudinal reinforcement, in2/ft mm2/m.Arc= required minimum cross section area of each cir-cumferential reinforcement, in2mm2.Arcs= cross section area of circumferential reinforcementactually selected, in
18、2mm2.Arl= required min cross section area of each longitudinalreinforcement, in2mm2.Arls= cross section area of longitudinal reinforcementactually selected, in2mm2.d = branch diameter, in. mm.db= nominal bolt diameter, in. mm.de= effective branch diameter, in. mm.dm= maximum branch pipe diameter for
19、 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 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 ea
20、ch 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 of fasteners required toattach each circumferential reinforcement.Nl= minimum total number of fasteners required toattach each longitudinal reinforc
21、ement.q = allowable load for each fastener, lbf N.tnp= bare steel thickness of pipe, in. mm.tnr= bare steel thickness of reinforcement in contact withpipe, 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 t
22、he 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 Design5.1 Reinforcement requirements depend upon pipe diam-eter, pipe wall profile, pipe wall thickness, density of fillmaterial, height of cover, an
23、d live load. Main pipes withintersecting branch pipes shall be investigated in accordancewith Section 6 to determine whether reinforcement is required.If reinforcement is required, it shall be designed in accordancewith the provisions of Sections 9 and 10, unless one of thealternatives specified in
24、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 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, u
25、nless the longitudinal distancebetween the centerlines of the branches measured along themain pipe is greater than D.5.3 This practice is limited to pipe with a live load that canbe described and quantified such as AASHTO H20 or HS20and AREA E80.5.4 Reinforcement design shall be based on an equivale
26、ntdepth 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 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)Ca
27、lculated 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 practice 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 thi
28、ckness based on therequirements of A 796/A 796M.5.8 This practice does not include the possible effects ofdragdown loads on vertical risers (manholes) such as caused bysettlement of deep fills.6. Need for Reinforcement6.1 The need for both longitudinal and circumferentialreinforcement as illustrated
29、 in Fig. 1 shall be considered.6.2 Longitudinal reinforcement needs shall be determinedfrom Tables 1-48 as applicable for the main pipe diameter andwall profile under consideration.5These tables list, for indi-cated branch pipe diameters, values of fill height, Hnlr, for5The diameter-thickness combi
30、nations listed in the tables do not necessarilymeet the requirements of A 796.FIG. 1 Schematic of ReinforcementsA 998/A 998M 98 (2003)2which no longitudinal reinforcement is required. If He# Hnlr,no longitudinal reinforcement is required; otherwise, longitu-dinal reinforcement shall be designed in a
31、ccordance 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 thelimitations of 5.2-5.6, do not require longitudinal reinforce-ment.6.3 Circumferential reinforcement n
32、eeds shall be deter-mined from Tables 49-54 as applicable for the wall profileunder consideration.5These tables list, for indicated main pipediameters and wall thicknesses, the maximum branch pipediameters, dm, for which no circumferential reinforcement isrequired. If de# dm, no circumferential rein
33、forcement 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, and 9 m. Use the 10 ft 3 m column for 1 # He# 10 ft 1# He# 3 m. For other Henot listed, interpolate b
34、etween thevalues listed.7. 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 permitted. The increasedthickness must be such that the pipe does not require rei
35、nforce-ment when checked in accordance with 6.2, if longitudinalreinforcement is omitted, and 6.3, if circumferential reinforce-ment is omitted.TABLE 1 Requirements for Longitudinal Reinforcement ofFittings in 48 in. Diameter Main Pipe with 2-23 by12 in.CorrugationsAEquivalent Fill Depth for Which N
36、o Longitudinal Reinforcement is Required,Hnlr, 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 f
37、t 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 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 thick
38、ness as required by A 796/A 796M.TABLE 2 Requirements for Longitudinal Reinforcement ofFittings in 1200 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
39、.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 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.
40、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. 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-
41、23 by12 in.CorrugationsAEquivalent Fill Depth for Which No Longitudinal Reinforcement is Required,Hnlr, 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, A
42、li, 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 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
43、 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 17.0 0.12ABranch pipe of any profile with specified thickness as required by A 796/A 796M.TABLE 4 Requirements for Longitudinal Reinforcement ofFittings in 1500 mm Diameter Main Pipe with 68 by 13 m
44、mCorrugationsAEquivalent 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 Hnlr, Ali, Hnlr, Ali, Hnlr, Ali, Hnlr,
45、 Ali, Hnlr, Ali,Dia., mm m mm2/m m mm2/m m mm2/m m mm2/m m mm2/m600 9.l 127 11.8 106 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 69
46、9 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 Reinforcement i
47、s Required,Hnlr, 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/
48、ft ft in.2/ft24 46.1 0.0530 35.5 0.0736 26.1 0.10 33.0 0.0842 19.2 0.13 24.0 0.10 29.0 0.0848 14.7 0.16 19.0 0.12 23.0 0.1054 11.6 0.20 15.0 0.15 18.0 0.1260 9.4 0.25 12.0 0.20 15.0 0.1666 7.8 0.29 10.0 0.22 12.0 0.1872 6.6 0.35 8.0 0.28 10.0 0.22ABranch pipe of any profile with specified thickness
49、as required by A 796/A 796M.A 998/A 998M 98 (2003)37.2 As a second alternative to providing required longitudi-nal or circumferential 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 sidesfrom the branch pipe a distance, a,ofde/4 or 6 in. 150 mm,whichever is greater. The saddle p
