1、Designation: D 7341 09Standard Practice forEstablishing Characteristic Values for Flexural Properties ofStructural Glued Laminated Timber by Full-Scale Testing1This standard is issued under the fixed designation D 7341; 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. Scope1.1 This practice describes procedures for full scale testingof structura
3、l glued laminated timber (glulam) to determine orverify characteristic values used to calculate flexural designproperties. Guidelines are given for: (1) testing individualstructural glued laminated timber lay-ups (with no modeling),(2) testing individual glulam combinations (with limited mod-eling),
4、 and (3) validating models used to predict characteristicvalues.1.2 This practice is limited to procedures for establishingflexural properties (Modulus of Rupture, MOR, and Modulusof Elasticity, MOE). Some of the principles for sampling andanalysis presented may be applicable to other properties.How
5、ever, other properties may require additional testing con-siderations that are beyond the scope of this practice.1.3 This practice is not intended to supersede the provisionsof Practice D 3737, but provides an alternative method forestablishing characteristic values. Lay-up combinations devel-oped i
6、n accordance with Practice D 3737 are not required to begoverned by this standard.NOTE 1The models described by Practice D 3737 have been devel-oped and modified based on more than 50 years of experience and manytest programs. In some cases, however, it may be desirable to develop anew model based o
7、n other input properties or using lumber materials orgrades not covered by that standard.1.4 Details of production, inspection, and certification arebeyond the scope of this document. However, for test results tobe representative of production, quality control systems shallbe in place to ensure cons
8、istent quality. Manufacturing shallconform to recognized manufacturing standards such as ANSI/AITC A190.1 or CSA O122.1.5 Adjustments to characteristic values to determine refer-ence values for design shall be in accordance with PracticeD 2915 for allowable stress design (ASD) or SpecificationD 5457
9、 for load and resistance factor design (LRFD).1.6 Adjustments to ASD reference values for end-use con-ditions intended for design purposes shall be performed inaccordance with Practice D 3737. The same adjustment factorsshall apply to LRFD reference values, except that the ASDload duration factor sh
10、all be replaced by an appropriate LRFDtime effect factor as determined in accordance with recognizedindustry practice.1.7 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.1.8 This standard does not purport to address all
11、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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 198 Test Methods of
12、Static Tests of Lumber in StructuralSizesD 245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded LumberD 2915 Practice for Evaluating Allowable Properties forGrades of Structural LumberD 3737 Practice for Establishing Allowable Properties forStructural
13、 Glued Laminated Timber (Glulam)D 4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural MaterialD 5456 Specification for Evaluation of Structural Compos-ite Lumber ProductsD 5457 Specification for Computing Reference Resistanceof Wood-Based Materials and Structural Connection
14、s forLoad and Resistance Factor DesignD 6815 Specification for Evaluation of Duration of Loadand Creep Effects of Wood and Wood-Based Products2.2 Other Standards:AITC Test T119 Full Size End Joint Tension Test3ANSI/AITC A190.1 American National Standard for WoodProducts Structural Glued Laminated Ti
15、mber31This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood Products.Current edition approved March 1, 2009. Published March 2009. Originallyapproved in 2008. Last previous edition approved in 2008 as
16、 D 7341 08.2For 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 Summary page onthe ASTM website.3Available from the American Institute of Timber C
17、onstruction (AITC), 7012 S.Revere Parkway Suite 140, Centennial, CO 80112, infoaitc-glulam.org1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.CSA O122 Structural Glued Laminated Timber4PS-20 Voluntary Product Standard, ALS53. Termino
18、logy3.1 Definitions of Terms Specific to This Standard:3.1.1 apparent properties, nMechanical properties as re-lated to the actual cross-sectional dimensions of the structuralglued laminated timber.3.1.2 characteristic value, nA test statistic from whichdesign values can be derived by the applicatio
19、n of appropriateadjustment factors. For strength properties of structural gluedlaminated timber, this value is typically a fifth percentileestimate with 75 % confidence. For deformation-based prop-erties, such as modulus of elasticity, this value is representedby the average value. Other statistics
20、are permitted to be usedas characteristic values for input properties of laminationsdepending on the model. Characteristic values for structuralglued laminated timber are typically based on apparent prop-erties.3.1.3 combination, nA series of lay-ups having similarlamination properties (grades, spec
21、ies, and end joint strengths),similar percentages of grade placement in the areas of criticalstresses, and similar predicted properties, that are groupedtogether for design purposes.NOTE 2An example of a lay-up combination based on PracticeD 3737 would be a 24F-V4 Douglas fir combination.3.1.4 lay-u
22、p, nThe specific arrangement of well-definedlamination grades for a single structural glued laminated timberdepth.3.1.5 model, nA mathematical method for predicting acharacteristic value for full-scale laminated timber based on theinput properties of the individual laminations.3.1.6 reference value,
23、 nThe characteristic value of amaterial that has been adjusted by the procedures in PracticeD 2915 or Specification D 5457 for use in design equations,but has not been adjusted for end-use conditions.3.1.7 structural glued laminated timber, nAproduct madefrom suitably selected and prepared pieces of
24、 componentlaminations, hereafter referred to as lumber in this practice butincluding sawn lumber, manufactured lumber, or structuralcomposite lumber, bonded together with an adhesive, with thegrain of all pieces essentially parallel to the longitudinal axis ofthe member.3.1.8 well-defined grade, nA
25、lumber grade with specificlimits on acceptable characteristics, such as knots, slope ofgrain, density, modulus of elasticity, tensile strength, etc., toensure reproducibility in production.4. Modeling Requirements4.1 General:4.1.1 Purpose for ModelingFor test results to be appli-cable to structural
26、glued laminated timber sizes that are nottested, it is necessary to relate the properties of the componentlaminations to the beam properties through the use of ananalytical model.4.1.2 Predictive ModelsModels that will be used to de-velop new combinations, predict characteristic values, andassign de
27、sign values shall be able to predict accurately thesevalues for a broad range of combinations. These results must bevalidated by full-scale tests according to appropriate testmethods for the property of interest.4.1.3 Single CombinationFor comparing different lay-upsand identifying critical sizes fo
28、r testing within a single com-bination, transformed section analysis is sufficient to predictthe stresses on each grade in the lay-up relative to the stressesin the tested lay-up. No further modeling shall be required.4.1.4 Single Lay-UpAll modeling requirements shall bewaived if the test results ar
29、e limited to a single, well-definedlay-up (that is, the number of laminations is fixed, thelamination properties are well defined, and the size (depth)tested is representative of the size intended for production).4.2 Minimum Model Inputs:4.2.1 GeneralAt a minimum, a suitable model shall bebased on d
30、efined lamination properties representative of thematerial used for each lamination and shall account for theplacement of different qualities of laminations throughout thecross section.4.2.2 Lamination PropertiesThe model shall account forboth lumber and end joint properties.4.2.2.1 Lumber GradeThe
31、species and grades of lumberused in structural glued laminated timber shall be well definedto ensure consistent performance between the grades used intest members and future production members. Strength andstiffness properties for the laminations shall be assignedaccording to the lumber grade. For d
32、eterministic models, theproperties assigned to the grade shall be a representativecharacteristic value for the grade. For probabilistic models, aparametric distribution of values shall be determined to repre-sent the grade.(1) SpeciesThe species or groups of species permitted bythe grade shall be we
33、ll defined and shall be represented in thetested members.(2) Modulus of ElasticityFor each grade of lumber used,the modulus of elasticity shall be determined in accordancewith Test Methods D 198 or D 4761 or by the procedures ofSpecification D 5456 or Practice D 245.(3) StrengthStrength values shall
34、 be assigned to eachgrade of lumber used in the laminated timber. Values shall bedetermined by testing in accordance with Test Methods D 198or D 4761 or by the procedures of Specification D 5456 orPractice D 245. Strength values are also permitted to beassigned to a grade zone based on its interacti
35、on with the beamas a whole. (For example, the IK/IGmodel used in PracticeD 3737 assigns strength values in this way.)(4) CreepStructural composite lumber for use in struc-tural glued laminated timber shall demonstrate creep perfor-mance similar to solid wood as demonstrated by SpecificationD 6815.4.
36、2.2.2 End Joint StrengthThe model shall include theeffect of end joints (if used) stressed in tension. Appropriate4Available from Canadian Standards Association (CSA), 5060 Spectrum Way,Mississauga, ON L4W 5N6, Canada, http:/www.csa.ca.5Available from National Institute of Standards and Technology (
37、NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.D7341092end joint tensile strengths shall be determined by full-scaletension testing in accordance with AITC Test T119 and main-tained through in-plant quality control procedures.4.2.3 Arrangement of Grades (Lay-Up)The
38、arrangementof laminations of varying quality throughout a laminatedtimber can significantly alter the stress distribution and perfor-mance of the member. The model shall account for these effectsif more than one grade of laminations is to be used. Theplacement of grades shall be well defined to ensu
39、re propermodeling and reproducibility in production.4.3 Minimum Model Analyses:4.3.1 Transformed-Section AnalysisThe stresses at thelocation of each change of grade in a cross section shall bedetermined using transformed section analysis. For determin-istic analyses, the average modulus of elasticit
40、y of each lumbergrade shall be used. The use of probabilistic models withsimulated values of modulus of elasticity is also acceptable.4.3.2 Prediction of PropertiesThe model shall predictcharacteristic values for the laminated timbers apparent prop-erties, based on the input lamination properties. A
41、dditionally,for strength properties, the model shall account for the possi-bility of any grade of lamination in the member controlling thestrength of the timber. The model shall identify the critical orcontrolling grade zone.5. Testing Requirements5.1 GeneralFull-scale member testing can be used to
42、(1)establish the properties of a single lay-up, (2) determine theproperties of a combination, or (3) validate a model intendedfor use in the prediction and assignment of characteristicvalues. Increased testing shall be required for validation of amodel, as compared to verifying the properties of a s
43、inglecombination or lay-up. Standard production procedures shallbe followed for the manufacture of all test specimens. Matchedend joint specimens shall be manufactured and tested inconjunction with tests of structural glued laminated timberutilizing end joints subject to tension.5.2 Test Certificati
44、onTesting shall be witnessed by aqualified third-party agency or conducted by an accreditedlaboratory that shall certify the test methods and results.5.3 Test MethodTests for flexural strength and modulus ofelasticity shall be conducted in accordance with Test MethodsD 198 or D 4761. If Test Method
45、D 4761 is used, the load rateshall be modified to be in accordance with Test Method D 198.Specimens shall be tested under dry-service conditions (mois-ture content 16 %) and adjusted to the standard moisturecontent of 12 % in accordance with Practice D 2915. Thetemperature of the test specimens shal
46、l not be less than 50Fnor more than 90F at the time of the tests.5.4 Sampling Requirements for a Single Lay-Up:5.4.1 Grading and Lay-UpLamination quality (grades,species, and end joint strength) and grade placement shall bewell defined and verified prior to testing.5.4.2 Specimen Size(s)Specimens fo
47、r testing shall be thespecific size (depth) of a single, well-defined lay-up in accor-dance with 4.1.4. Width of the specimens shall be representa-tive of the size intended for production. For horizontallylaminated beams, a single width is permitted to be consideredrepresentative of members with wid
48、ths not more than 2 in.wider nor 2 in. narrower than the tested width, provided thatthe selection (grading) criteria relative to the cross-sectionalsize is the same for each width. For vertically laminated beams,the depth of test specimens shall be representative of intendedproduction sizes, and the
49、 width shall be based on the number oflaminations and shall be equal to the number of laminationsintended for use in production.5.4.3 Sample SizeA minimum of 30 specimens shall berequired for each lay-up.5.4.4 FacilitiesIf the lay-up is intended to be produced inmultiple facilities, samples shall be obtained from enoughplants to represent all major processing variables includinglumber characteristics and end joint strength.5.5 Sampling Requirements for a Single Combination:5.5.1 Lay-Ups and Sample SizeFor horizontally lami-nated beams, a minim
