1、Designation: F2787 11F2787 13 An 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 a
2、doption or, 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 thermoplastic corrug
3、ated wall arch-shaped chambers used for collection,detention, and retention of stormwater runoff. The practice is for chambers installed in a trench or bed and subjected to earth andlive loads. Structural design includes the composite system made up of the chamber arch, the chamber foot, and the soi
4、l envelope.Relevant recognized practices include design of thermoplastic culvert pipes and design of foundations.1.2 This practice standardizes methods for manufacturers of buried thermoplastic structures to design for the time dependentbehavior of plastics using soil support as an integral part of
5、the structural system. This practice is not applicable to thermoplasticstructures that do not include soil support as a component of the structural system.1.3 This practice is limited to structural design and does not provide guidance on hydraulic, hydrologic, or environmental designconsiderations t
6、hat may need to be addressed for functional use of stormwater collection chambers.1.4 Stormwater chambers are most commonly embedded in open graded, angular aggregate which provide both structuralsupport and open porosity for water storage. Should soils other than open graded, angular aggregate be s
7、pecified for embedment,other installation and functional concerns may need to be addressed that are outside the scope of this practice.1.5 Chambers are produced in arch shapes to meet classifications that specify chamber rise, chamber span, minimum foot width,minimum wall thickness, and minimum arch
8、 stiffness constant. Chambers are manufactured with integral footings.1.6 Polypropylene chamber classifications are found in Specification F2418. Specification F2418 also specifies chambermanufacture and qualification.1.7 This practice is applicable to design in inch-pound units. The SI units in par
9、enthesis are given for information only.Thevalues stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversionsto SI units that are provided for information only and are not considered standard.1.8 This standard does not purport to address al
10、l of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2487 Practice for Cla
11、ssification of Soils for Engineering Purposes (Unified Soil Classification System)D2990 Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of PlasticsD6992 Test Method for Accelerated Tensile Creep and Creep-Rupture of Geosynthetic Materials Based on Time-TemperatureSuperpos
12、ition Using the Stepped Isothermal MethodF2418 Specification for Polypropylene (PP) Corrugated Wall Stormwater Collection Chambers2.2 AASHTO LRFD Bridge Design Specifications:3Section 3 Loads and Load Factors, 3.5 Permanent Loads; 3.6 Live LoadsSection 10 Foundations, 10.6 Spread Footings1 This prac
13、tice is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the direct responsibility of Subcommittee F17.65 on Land Drainage.Current edition approved April 1, 2011April 1, 2013. Published April 2011April 2013. Originally approved in 2009. Last previous edition approved in
14、20092011 asF278709.11. DOI: 10.1520/F2787-09.10.1520/F2787-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website
15、.3 AASHTO LRFD Bridge Design Specifications-Dual Units, 4th Edition, 2007 and AASHTO Standard Specifications for Transportation Materials and Sampling, 28thedition, 2008. Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Wa
16、shington, DC 20001.This 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 possible to adequately depict all changes accurately, ASTM recommends that user
17、s 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
18、ocken, PA 19428-2959. United States1Section 12 Buried Structures and Tunnel Liners, 12.12 Thermoplastic Pipes2.3 AASHTO Standard Specifications:3M 43 Standard Specification for Size of Aggregate for Road and Bridge ConstructionM 145 Standard Specification for Classification of Soils and Soil-Aggrega
19、te Mixtures for Highway Construction PurposesT 99 Standard Method of Test for Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.)Drop2.4 AWWA Manual:4M 45 Manual of Water Supply Practices: Fiberglass Pipe Design3. Terminology3.1 Definitions:3.1.1 Definitions used
20、 in this specification are in accordance with the definitions in Terminology F412, and abbreviations arein accordance with Terminology D1600, unless otherwise indicated.3.1.2 chamberan arch-shaped structure manufactured of thermoplastic with an open-bottom that is supported on feet and maybe joined
21、into rows that begin with, and are terminated by, end caps (see Fig. 1).3.1.3 classificationthe chamber model specification that identifies nominal height, nominal width, rise, span, minimum footwidth, wall thickness, and arch stiffness constant.3.1.4 corrugated walla wall profile consisting of a re
22、gular pattern of alternating crests and valleys connected by web elements(see Fig. 2).3.1.5 crestthe element of a corrugation located at the exterior surface of the chamber wall, spanning between two webelements (see Fig. 2).3.1.6 crownthe center section of a chamber typically located at the highest
23、 point as the chamber is traversed circumferentially.3.1.7 embedmentbackfill material against the sides of chambers and end caps and in between rows of chambers from thefoundation stone below to a specified dimension over the top of the chambers (see Fig. 3).3.1.8 end capa bulkhead provided to begin
24、 and terminate a chamber, or row of chambers, and prevent intrusion of surroundingembedment materials.3.1.9 foota flat, turned out section that is manufactured with the chamber to provide a bearing surface for transfer of verticalloads to the foundation (see Fig. 1).3.1.10 foot areathe actual contac
25、t area of the foot with the foundation.3.1.11 local bucklingcompression failure of built-up plate sections with high width-to-thickness ratios.3.1.12 nominal heighta designation describing the approximate outside vertical dimension of the chamber at its crown (seeFig. 1).3.1.13 nominal widtha design
26、ation describing the approximate outside horizontal dimension of the chamber at its feet (seeFig. 1).4 AWWA Manual of Water Supply Practices M45: Fiberglass Pipe Design, 2nd Edition, 2005. Available from the American Water Works Association (AWWA), 6666 W.Quincy Ave., Denver, CO 80235.NOTE 1The mode
27、l chamber shown in this standard is intended only as a general illustration.FIG. 1 Chamber Terminology (Typical)F2787 1323.1.14 risethe vertical distance from the chamber base (bottom of the chamber foot) to the inside of a chamber wall valleyelement at the crown as depicted in Fig. 1.3.1.15 spanthe
28、 horizontal distance from the interior of one sidewall valley element to the interior of the other sidewall valleyelement as depicted in Fig. 1.3.1.16 valleythe element of a corrugation located at the interior surface of a chamber wall, spanning between two webelements (see Fig. 2).3.1.17 viscoelast
29、icitythe response of a material to load that is dependent both on load magnitude (elastic) and load rate(viscous).3.1.18 webthe element of a corrugated wall that connects a crest element to a valley element (see Fig. 2).4. Significance and Use4.1 This practice provides a rational method for structur
30、al design of thermoplastic stormwater chambers. The loads, capacities,and limit states are based on accepted load and resistance factor design for thermoplastic pipes; however, existing designspecifications for thermoplastic pipes do not adequately address the design of chambers due to (1) open-bott
31、om geometry, (2)support on integral foot, (3) varying circumferential corrugation geometry, and (4) manufacture with alternative thermoplasticresin. This practice standardizes recommendations for designers to adequately address these aspects of chamber design.4.2 This practice is written to allow ch
32、amber manufacturers to evaluate chambers meeting existing classifications and to designchambers for new classifications as they are developed.5. Basis of Design5.1 Design is based on AASHTO LRFD Bridge Design Specifications and publications for static soil-structure-interactionanalysis for thermopla
33、stic pipes. Users should verify that these recommendations meet particular project needs.5.2 Chamber installations shall be designed for the critical combination of live load and dead load, see Section 7.NOTE 1The corrugation profile shown in this standard is intended only as a general illustration.
34、FIG. 2 Corrugation Terminology (Typical)FIG. 3 Installation Terminology (Typical)F2787 1335.3 Chambers shall be designed for service limit states and safety against structural failure, see Section 8.5.3.1 Service Limit StateService design shall limit vertical displacements at the ground surface. Cha
35、mbers shall be evaluatedfor detrimental structural deformation.5.3.2 Safety Against Structural FailureStructural design shall evaluate chambers for buckling, compression, tension, andfoundation bearing.5.4 Buckling capacity is based on material stress limits. Compression and tension capacities are b
36、ased on material strain limits.Foundation bearing capacity is based on soil ultimate 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 gene
37、rally precludes the use of closed-form solutions for determination of design force effects. Whilespecific solutions may be developed for individual chamber geometries, general solutions have not been developed to accurately predict behavior for themany possible variations in chamber geometry. In mos
38、t cases FEA must be employed to calculate design force effects on the chamber or as verificationof closed-form solutions.5.6 Chamber material properties shall be based on tests.5.7 Chamber section properties shall be calculated from the geometry of the chamber cross-section.5.8 Soil properties shall
39、 be based on generally accepted published properties for the specified soil classifications or by tests onsite-specific materials.6. Analysis for Design6.1 The design shall include structural modeling of the chamber under loads in the installed soil environment. Analysis modelsshall include critical
40、 anticipated live loads and soil cover heights that provide deflections for serviceability design and force effectsto design for safety against structural failure.6.2 Analysis shall consider the following:6.2.1 Chamber StructureTwo-dimensional FEA shall use beam elements with effective section prope
41、rties to model thechamber wall. Each beam element shall represent not more than 10 degrees of the chamber circumference. Nodes at beam endsshall be located at the center of the gravity (cg) of the corrugated chamber wall cross-section. Three-dimensional FEAshall employshell elements.6.2.2 FEA Progra
42、mAcceptable FEAprograms include (1) CANDE (CulvertAnalysis and Design), (2) similarly featured andverified culvert design software, or (3) general purpose finite element analysis software with capability to model nonlinear staticsoil-structure-interaction.6.2.3 CreepThe time-dependent response (cree
43、p) of thermoplastic chamber materials shall be included in the analysis.Acceptable methods are (1) multiple linear-elastic models with successive stiffness reductions for creep effects, and (2) nonlinearchamber models that include the creep response. Values of creep modulus shall be determined by te
44、st in accordance with TestMethods D2990 or Test Method D6992.6.2.4 SoilModels shall include accurate representation of the structural backfill envelope and boundary conditions. Thebackfill envelope includes foundation, embedment, and cover. Boundary conditions typically include the size of the soile
45、mbedment zone, distance to trench walls, subgrade under the backfill envelope, weight and stiffness of soils above the backfillenvelope, and boundary for application of live loads. Structural backfill soils shall be modeled with nonlinear properties thatincorporate the effects of confinement. Accept
46、able soil models include (1) soil hardening models that increase soil stiffness forconfinement, (2) elastic-plastic models that allow failure in shear, or (3) large-deformation models. Soils outside the backfillenvelope and further than two times the chamber span from the chamber may be modeled as l
47、inear-elastic. Soil continuumelements shall be either fully bonded to the chamber beam elements or modeled with a friction interface.6.2.5 Live LoadModels shall include live loads, see Section 7.6.2.6 Chamber BedsStructural effects of adjacent chambers shall be analyzed. When two-dimensional plane-s
48、train analysisis used, changes in geometry along the length of chamber runs, including intermediate stiffeners or diaphragms, shall be addressedusing separate models.7. Structural Loads7.1 The design load on a chamber shall include dead load and live load.7.2 Dead Load (DL)Dead load shall be compute
49、d from permanent soil cover over chambers. The soil unit weight shall notbe less than 120 lb/ft3 (18.9 kN/m3) unless otherwise determined by tests. Dead load shall be calculated for each installation.7.3 Dead Load Factor (DL)The dead load factor shall be 1.95.7.4 Live Load (LL)Live load calculation is provided in Annex A1. Live load includes transient loads (passing vehicles) orsustained loads (stationary non-permanent loads). Live load computation is based on the AASHTO HL-93 design vehicular liveload applied to a single-loaded lane.F2787 1347.
