1、Designation: F2787 11An American National StandardStandard Practice forStructural Design of Thermoplastic Corrugated WallStormwater Collection Chambers1This standard is issued under the fixed designation F2787; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice standardizes structural design of thermo-plastic corrugated wal
3、l arch-shaped chambers used for collec-tion, detention, and retention of stormwater runoff. The prac-tice is for chambers installed in a trench or bed and subjectedto earth and live loads. Structural design includes the compos-ite system made up of the chamber arch, the chamber foot, andthe soil env
4、elope. Relevant recognized practices include designof thermoplastic culvert pipes and design of foundations.1.2 This practice standardizes methods for manufacturers ofburied thermoplastic structures to design for the time depen-dent behavior of plastics using soil support as an integral partof the s
5、tructural system. This practice is not applicable tothermoplastic structures that do not include soil support as acomponent of the structural system.1.3 This practice is limited to structural design and does notprovide guidance on hydraulic, hydrologic, or environmentaldesign considerations that may
6、 need to be addressed forfunctional use of stormwater collection chambers.1.4 Stormwater chambers are most commonly embedded inopen graded, angular aggregate which provide both structuralsupport and open porosity for water storage. Should soils otherthan open graded, angular aggregate be specified f
7、or embed-ment, other installation and functional concerns may need to beaddressed that are outside the scope of this practice.1.5 Chambers are produced in arch shapes to meet classifi-cations that specify chamber rise, chamber span, minimum footwidth, minimum wall thickness, and minimum arch stiffne
8、ssconstant. Chambers are manufactured with integral footings.1.6 Polypropylene chamber classifications are found inSpecification F2418. Specification F2418 also specifies cham-ber manufacture and qualification.1.7 This practice is applicable to design in inch-pound units.The SI units in parenthesis
9、are given for information only.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitatio
10、ns prior to use.2. Referenced Documents2.1 ASTM Standards:2D2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D2990 Test Methods for Tensile, Compressive, and Flex-ural Creep and Creep-Rupture of PlasticsD6992 Test Method for Accelerated Tensile Cr
11、eep andCreep-Rupture of Geosynthetic Materials Based on Time-Temperature Superposition Using the Stepped IsothermalMethodF2418 Specification for Polypropylene (PP) CorrugatedWall Stormwater Collection Chambers2.2 AASHTO LRFD Bridge Design Specifications:3Section 3 Loads and Load Factors, 3.5 Permane
12、nt Loads;3.6 Live LoadsSection 10 Foundations, 10.6 Spread FootingsSection 12 Buried Structures and Tunnel Liners, 12.12Thermoplastic Pipes2.3 AASHTO Standard Specifications:3M43 Standard Specification for Size ofAggregate for Roadand Bridge ConstructionM 145 Standard Specification for Classificatio
13、n of Soils andSoil-Aggregate Mixtures for Highway Construction Pur-posesT99Standard Method of Test for Moisture-Density Rela-tions of Soils Using a 2.5-kg (5.5-lb) Rammer and a1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of
14、Subcommittee F17.65 on LandDrainage.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 2009. Last previous edition approved in 2009 as F278709. DOI:10.1520/F2787-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
15、at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3AASHTO LRFD Bridge Design Specifications-Dual Units, 4th Edition, 2007and AASHTO Standard Specifications for Transportation Materials and Sampling,28th edition, 2
16、008. Available from American Association of State Highway andTransportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washing-ton, DC 20001.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
17、ken, PA 19428-2959, United States.305-mm (12-in.) Drop2.4 AWWA Manual:4M 45 Manual of Water Supply Practices: Fiberglass PipeDesign3. Terminology3.1 DefinitionsDefinitions used in this specification are inaccordance with the definitions in Terminology F412, andabbreviations are in accordance with Te
18、rminology D1600,unless otherwise indicated.3.1.1 chamberan arch-shaped structure manufactured ofthermoplastic with an open-bottom that is supported on feetand may be joined into rows that begin with, and are termi-nated by, end caps (see Fig. 1).3.1.2 classificationthe chamber model specification th
19、atidentifies nominal height, nominal width, rise, span, minimumfoot width, wall thickness, and arch stiffness constant.3.1.3 corrugated walla wall profile consisting of a regularpattern of alternating crests and valleys connected by webelements (see Fig. 2).3.1.4 crestthe element of a corrugation lo
20、cated at theexterior surface of the chamber wall, spanning between twoweb elements (see Fig. 2).3.1.5 crownthe center section of a chamber typicallylocated at the highest point as the chamber is traversedcircumferentially.3.1.6 embedmentbackfill material against the sides ofchambers and end caps and
21、 in between rows of chambers fromthe foundation stone below to a specified dimension over thetop of the chambers (see Fig. 3).3.1.7 end capa bulkhead provided to begin and terminatea chamber, or row of chambers, and prevent intrusion ofsurrounding embedment materials.3.1.8 foota flat, turned out sec
22、tion that is manufacturedwith the chamber to provide a bearing surface for transfer ofvertical loads to the foundation (see Fig. 1).3.1.9 foot areathe actual contact area of the foot with thefoundation.3.1.10 local bucklingcompression failure of built-up platesections with high width-to-thickness ra
23、tios.3.1.11 nominal heighta designation describing the ap-proximate outside vertical dimension of the chamber at itscrown (see Fig. 1).3.1.12 nominal widtha designation describing the ap-proximate outside horizontal dimension of the chamber at itsfeet (see Fig. 1).3.1.13 risethe vertical distance fr
24、om the chamber base(bottom of the chamber foot) to the inside of a chamber wallvalley element at the crown as depicted in Fig. 1.3.1.14 spanthe horizontal distance from the interior ofone sidewall valley element to the interior of the other sidewallvalley element as depicted in Fig. 1.3.1.15 valleyt
25、he element of a corrugation located at theinterior surface of a chamber wall, spanning between two webelements (see Fig. 2).3.1.16 viscoelasticitythe response of a material to loadthat is dependent both on load magnitude (elastic) and load rate(viscous).3.1.17 webthe element of a corrugated wall tha
26、t connectsa crest element to a valley element (see Fig. 2).4. Significance and Use4.1 This practice provides a rational method for structuraldesign of thermoplastic stormwater chambers. The loads,capacities, and limit states are based on accepted load andresistance factor design for thermoplastic pi
27、pes; however,existing design specifications for thermoplastic pipes do notadequately address the design of chambers due to (1) open-bottom geometry, (2) support on integral foot, (3) varyingcircumferential corrugation geometry, and (4) manufacturewith alternative thermoplastic resin. This practice s
28、tandardizesrecommendations for designers to adequately address theseaspects of chamber design.4.2 This practice is written to allow chamber manufacturersto evaluate chambers meeting existing classifications and todesign chambers for new classifications as they are developed.4AWWA Manual of Water Sup
29、ply Practices M45: Fiberglass Pipe Design, 2ndEdition, 2005. Available from the American Water Works Association (AWWA),6666 W. Quincy Ave., Denver, CO 80235.NOTEThe model chamber shown in this standard is intended only as a general illustration.FIG. 1 Chamber Terminology (Typical)F2787 1125. Basis
30、of Design5.1 Design is based on AASHTO LRFD Bridge DesignSpecifications and publications for static soil-structure-interaction analysis for thermoplastic pipes. Users shouldverify that these recommendations meet particular projectneeds.5.2 Chamber installations shall be designed for the criticalcomb
31、ination of live load and dead load, see Section 7.5.3 Chambers shall be designed for service limit states andsafety against structural failure, see Section 8.5.3.1 Service Limit StateService design shall limit verti-cal displacements at the ground surface. Chambers shall beevaluated for detrimental
32、structural deformation.5.3.2 Safety Against Structural FailureStructural designshall evaluate chambers for buckling, compression, tension,and foundation bearing.5.4 Buckling capacity is based on material stress limits.Compression and tension capacities are based on materialstrain limits. Foundation
33、bearing capacity is based on soilultimate bearing capacity.5.5 Chambers shall be designed using closed-form solutions(verified by analysis) or finite element analysis (FEA). Designsshall be validated by testing.NOTE 1The soil-chamber system complexity generally precludes theuse of closed-form soluti
34、ons for determination of design force effects.While specific solutions may be developed for individual chambergeometries, general solutions have not been developed to accuratelypredict behavior for the many possible variations in chamber geometry. Inmost cases FEA must be employed to calculate desig
35、n force effects on thechamber or as verification of closed-form solutions.5.6 Chamber material properties shall be based on tests.5.7 Chamber section properties shall be calculated from thegeometry of the chamber cross-section.5.8 Soil properties shall be based on generally acceptedpublished propert
36、ies for the specified soil classifications or bytests on site-specific materials.6. Analysis for Design6.1 The design shall include structural modeling of thechamber under loads in the installed soil environment.Analysismodels shall include critical anticipated live loads and soilcover heights that
37、provide deflections for serviceability designand force effects to design for safety against structural failure.6.2 Analysis shall consider the following:6.2.1 Chamber StructureTwo-dimensional FEA shall usebeam elements with effective section properties to model thechamber wall. Each beam element sha
38、ll represent not morethan 10 degrees of the chamber circumference. Nodes at beamends shall be located at the center of the gravity (cg) of theNOTEThe corrugation profile shown in this standard is intended only as a general illustration.FIG. 2 Corrugation Terminology (Typical)FIG. 3 Installation Term
39、inology (Typical)F2787 113corrugated chamber wall cross-section. Three-dimensionalFEA shall employ shell elements.6.2.2 FEA ProgramAcceptable FEAprograms include (1)CANDE (Culvert Analysis and Design), (2) similarly featuredand verified culvert design software, or (3) general purposefinite element a
40、nalysis software with capability to modelnonlinear static soil-structure-interaction.6.2.3 CreepThe time-dependent response (creep) of ther-moplastic chamber materials shall be included in the analysis.Acceptable methods are (1) multiple linear-elastic models withsuccessive stiffness reductions for
41、creep effects, and (2) non-linear chamber models that include the creep response. Valuesof creep modulus shall be determined by test in accordancewith Test Methods D2990 or Test Method D6992.6.2.4 SoilModels shall include accurate representation ofthe structural backfill envelope and boundary condit
42、ions. Thebackfill envelope includes foundation, embedment, and cover.Boundary conditions typically include the size of the soilembedment zone, distance to trench walls, subgrade under thebackfill envelope, weight and stiffness of soils above thebackfill envelope, and boundary for application of live
43、 loads.Structural backfill soils shall be modeled with nonlinearproperties that incorporate the effects of confinement. Accept-able soil models include (1) soil hardening models that increasesoil stiffness for confinement, (2) elastic-plastic models thatallow failure in shear, or (3) large-deformati
44、on models. Soilsoutside the backfill envelope and further than two times thechamber span from the chamber may be modeled as linear-elastic. Soil continuum elements shall be either fully bonded tothe chamber beam elements or modeled with a friction inter-face.6.2.5 Live LoadModels shall include live
45、loads, see Sec-tion 7.6.2.6 Chamber BedsStructural effects of adjacent cham-bers shall be analyzed. When two-dimensional plane-strainanalysis is used, changes in geometry along the length ofchamber runs, including intermediate stiffeners or diaphragms,shall be addressed using separate models.7. Stru
46、ctural Loads7.1 The design load on a chamber shall include dead loadand live load.7.2 Dead Load (DL)Dead load shall be computed frompermanent soil cover over chambers. The soil unit weight shallnot be less than 120 lb/ft3(18.9 kN/m3) unless otherwisedetermined by tests. Dead load shall be calculated
47、 for eachinstallation.7.3 Dead Load Factor (gDL)The dead load factor shall be1.95.7.4 Live Load (LL)Live load calculation is provided inAnnex A1. Live load includes transient loads (passing ve-hicles) or sustained loads (stationary non-permanent loads).Live load computation is based on theAASHTO HL-
48、93 designvehicular live load applied to a single-loaded lane.7.4.1 HL-93The HL-93 load is a combination of thedesign truck or design tandem, whichever is critical, appliedwith the design lane load.7.4.2 Design TruckThe design truck shall be theAASHTO Design Truck as specified in AASHTO LRFDBridge De
49、sign Specifications, Section 3.6.1.2.2.7.4.3 Design TandemThe design tandem shall be theAASHTO Design Tandem as specified in AASHTO LRFDBridge Design Specifications, Section 3.6.1.2.3.7.4.4 Thermoplastic chamber structures have a structuralresponse that is dependent on load duration. Chamber responseto live load is computed using appropriate creep moduli forinstantaneous response (transient loads) and longer-durationresponse (sustained loads). As a minimum, design for live loadshall include evaluation of instantaneous response (due tomoving vehicl
