1、Designation:A998/A998M08 Designation: A998/A998M 12Standard Practice forStructural Design of Reinforcements for Fittings inFactoryMade Corrugated Steel Pipe for Sewers and OtherApplications1This standard is issued under the fixed designation A998/A998M; the number immediately following the designati
2、on 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the structural
3、 design of reinforcement for fittings in factory-made, round corrugated steel pipe,conforming to Specifications A760/A760M or A762/A762M, for use as storm and sanitary sewers and other buried applications.This practice is for fittings on pipe installed in a trench or embankment and subjected to eart
4、h loads and live loads. It must berecognized that a buried corrugated pipe is a composite structure made up of the steel ring and the soil envelope, and both elementsplay a vital part. Both main and branch pipe shall be designed in accordance with Practice A796/A796M and installed inaccordance with
5、Practice A798/A798M.1.2 This practice covers the structural design of reinforcement for fittings such as those for branch pipes. Refer to Section 5 fordesign limitations.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilit
6、yof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 The values stated in either inch-pound units or SI units shall be regarded separately as standard. The values stated in eachsystem are not exac
7、t equivalents; therefore, each system must be used independently of the other, without combining values in anyway. SI units are shown in brackets in the text for clarity, but they are the applicable values when the design is to be performedusing SI units.2. Referenced Documents2.1 ASTM Standards:2A3
8、6/A36M Specification for Carbon Structural SteelA153/A153M Specification for Zinc Coating (Hot-Dip) on Iron and Steel HardwareA307 Specification for Carbon Steel Bolts and Studs, 60 000 PSI Tensile StrengthA760/A760M Specification for Corrugated Steel Pipe, Metallic-Coated for Sewers and DrainsA762/
9、A762M Specification for Corrugated Steel Pipe, Polymer Precoated for Sewers and DrainsA796/A796M Practice for Structural Design of Corrugated Steel Pipe, Pipe-Arches, and Arches for Storm and Sanitary Sewersand Other Buried ApplicationsA798/A798M Practice for Installing Factory-Made Corrugated Steel
10、 Pipe for Sewers and Other ApplicationsA902 Terminology Relating to Metallic Coated Steel ProductsA929/A929M Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel PipeF568M Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners (Metric)2.2
11、AASHTO Standard:3Standard Specifications for Highway BridgesLRFD Bridge Design Specifications2.3 American Railway Engineering and Maintenance-of-Way Association:1This practice is under the jurisdiction of ASTM Committee A05 on Metallic-Coated Iron and Steel Products and is the direct responsibility
12、of Subcommittee A05.17on Corrugated Steel Pipe Specifications .Current edition approved May 1, 2008.2012. Published June 2008.2012. Originally approved in 1998. Last previous edition approved in 19982008 as A998/A998M-98(2003).A998/A998M - 08. DOI: 10.1520/A0998_A0998M-0812.2For referenced ASTM stan
13、dards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from American Association of State Highway and Transportation Officials (
14、AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically pos
15、sible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
16、est Conshohocken, PA 19428-2959, United States.AREMA Manual42.4 Society of Automotive Engineers:J978,J78 Steel Self-Drilling Tapping Screws53. Terminology3.1 For definitions of general terms used in this standard, refer to Terminology A902.3.2 Definitions of Terms Specific to This Standard:3.2.1 bra
17、nch pipecorrugated pipe with a diameter smaller than or equal to that of the main pipe, carrying a portion of the flowand connected to the main pipe through a fitting welded in place.3.2.2 fittingssections of main pipe fabricated to accommodate branch pipes or manhole pipes.3.2.3 main pipecorrugated
18、 pipe carrying the primary flow.3.2.4 reinforcementsheets, bars, or structural members connected to the main pipe to strengthen a fitting.4. Symbols4.1 The symbols used in this practice have the following significance:a = distance of saddle plate extension onto main pipe, in. mm.Ali= incremental req
19、uired min cross section area of each longitudinal reinforcement, in2/ft mm2/m.Arc= required minimum cross section area of each circumferential reinforcement, in2mm2.Arcs= cross section area of circumferential reinforcement actually selected, in2mm2.Arl= required min cross section area of each longit
20、udinal reinforcement, in2mm2.Arls= cross section area of longitudinal reinforcement actually 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 which no circumferential reinforcement is required in
21、. 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 reinforcement is required, ft m.L = total length of each longitudinal reinforcement, in. mm.Lw= length of we
22、ld, in. mm.LL = live load pressure (see Practice A796/A796M), lbf/ft2kPa.Nc= minimum total number of fasteners required to attach each circumferential reinforcement.Nl= minimum total number of fasteners required to attach each longitudinal reinforcement.q = allowable load for each fastener, lbf N.tn
23、p= bare steel thickness of pipe, in. mm.tnr= bare steel thickness of reinforcement in contact with pipe, 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 material above the pipe, lbf/ft3kN/m3. When actual fill material
24、is not knownuse 120 lbf/ft319 kN/m3.a = acute angle between main and branch pipe, degrees.5. Basis of Design5.1 Reinforcement requirements depend upon pipe diameter, pipe wall profile, pipe wall thickness, density of fill material,height of cover, and live load. Main pipes with intersecting branch p
25、ipes shall be investigated in accordance with Section 6 todetermine whether reinforcement is required. If reinforcement is required, it shall be designed in accordance with the provisionsof Sections 9 and 10, unless one of the alternatives specified in Section 7 is met. Fittings in main pipes with a
26、 diameter less than48 in. 1200 mm, subject to the limitations of 5.2-5.6, do not require reinforcement.5.2 This practice does not apply to cases where there are two branch pipes on opposite sides of the main pipe, each with adiameter greater than 0.75D, unless the longitudinal distance between the c
27、enterlines of the branches measured along the main pipeis greater than D.5.3 This practice is limited to pipe with a live load that can be described and quantified such as AASHTO H20 or HS20 andAREMA E80.4Available from American Railway Engineering and Maintenance-of-Way Association (AREMA), 8201 Co
28、rporate Drive, Suite 1125, Landover, MD 207852230.5Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001.5Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http:/www.sae.org.A998/A998M 1225.4 Reinforcement design
29、shall be based on an equivalent depth of fill (He) that accounts for both earth load and live load (LL)as follows:He5LL 1 wH120FHe5LL 1 wH19G(1)A0998_A0998M-12_1This practice is limited to pipe with He# 30 ft 9 m.5.5 Reinforcement design shall be based on an effective branch diameter (de) determined
30、 for the branch angle (a) as follows:A0998_A0998M-12_2Calculated values of deshall be rounded up to the next 6 in. 150 mm increment for design calculations. The value of demustnot exceed 1.16D.5.6 This practice is further limited to a from 30 to 90, inclusive.5.7 This practice applies where the bran
31、ch pipe is welded to the main pipe and has a specified thickness based on therequirements of A796/A796M.5.8 This practice does not include the possible effects of dragdown loads on vertical risers (manholes) such as caused bysettlement of deep fills.6. Need for Reinforcement6.1 The need for both lon
32、gitudinal and circumferential reinforcement as illustrated in Fig. 1 shall be considered.6.2 Longitudinal reinforcement needs shall be determined from Tables 1-48 as applicable for the main pipe diameter and wallprofile under consideration.6These tables list, for indicated branch pipe diameters, val
33、ues of fill height, Hnlr, for which nolongitudinal reinforcement is required. If He# Hnlr, no longitudinal reinforcement is required; otherwise, longitudinalreinforcement shall be designed in accordance with Section 9. For main pipe diameters not included in Tables 1-48, interpolationshall be permit
34、ted. Fittings for branch pipes with a diameter less than shown in Tables 1-48, subject to the limitations of 5.2-5.6,do not require longitudinal reinforcement.6.3 Circumferential reinforcement needs shall be determined from Tables 49-54 as applicable for the wall profile underconsideration.6These ta
35、bles list, for indicated main pipe diameters and wall thicknesses, the maximum branch pipe diameters, dm,for which no circumferential reinforcement is required. If de# dm, no circumferential reinforcement is required; otherwise,circumferential reinforcement shall be designed in accordance with Secti
36、on 10. Branch diameters are listed for equivalent depthsof 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 between the values listed.7. Alternatives to Providing Reinforcement7.1 As an alternative to providing
37、required longitudinal or circumferential reinforcement, or both, an increase in the thicknessof the main pipe shall be permitted. The increased thickness must be such that the pipe does not require reinforcement whenchecked in accordance with 6.2, if longitudinal reinforcement is omitted, and 6.3, i
38、f circumferential reinforcement is omitted.7.2 As a second alternative to providing required longitudinal or circumferential reinforcement, or both, it is permissible toprovide a saddle plate as illustrated in Fig. 2 with a thickness selected from Tables 55 and 56. Saddle plates that act asreinforce
39、ment must be of the same material and wall profile as the main pipe and must extend onto the main pipe on all sides fromthe branch pipe a distance, a,ofde/4 or 6 in. 150 mm, whichever is greater. The saddle plate must be continuously welded to6The diameter-thickness combinations listed in the tables
40、 do not necessarily meet the requirements of A796/A796M.FIG. 1 Schematic of ReinforcementsA998/A998M 123a stub length of the branch pipe. The stub must have a full uncut section at least 12 in. 300 mm long. The saddle plate must beconnected to the main pipe with sufficient fasteners (welds, bolts, o
41、r screws) so that there are no large gaps and so that it will acttogether with the main pipe.7.3 As an alternative to providing required longitudinal reinforcement, it is permissible to provide a beam type reinforcementas illustrated in Fig. 3, designed using recognized engineering principles.FIG. 2
42、 Schematic of Saddle PlateFIG. 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
43、 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 37.4 0.05 48.2 0.04 69.1 0.043
44、0 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 thickness as required byA796/A796M.TABLE 2 Requirements for Longitudinal Reinfor
45、cement 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 mmThick2.01 mmThick2.77 mmThick3.51 mmThick4.27 mmThickMain Pipe Main Pipe Main Pipe M
46、ain 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. 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
47、 381. 5.1 318. 6.7 254. 8.5 191. 10.4 148.ABranch pipe of any profile with specified thickness as required byA796/A796M.A998/A998M 1248. Materials8.1 Any reinforcement required shall be a continuous sheet, bar, or structural member. Sheets for longitudinal reinforcementshall be flat sheets, but eith
48、er flat sheets or circumferentially corrugated sheets are permitted for circumferential reinforcement.Sheets for reinforcement shall meet the requirements of A929/A929M, having the same metallic coating as the pipe to which thereinforcement is attached. Structural members or bars for reinforcement s
49、hall meet the requirements of Specification A36/A36M.Reinforcement shall have suitable corrosion protection.8.2 Mechanical fasteners used to attach reinforcement shall be galvanized in accordance with Specification A153/A153M.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, and Incremental Longitudinal Reinforcement Area, Ali0.064 in.Thick0.079 in.Thi
